Welcome to HBES 2013

Conference Participants:

Welcome to the 25th annual meeting of the Human Behavior and Evolution Society at the Loews Miami Beach Hotel.

The conference format has changed this year in that we have created a Wednesday afternoon session and eliminated the Sunday morning session. This was done, in part, to prevent the Sunday exodus from reducing the attendance of Sunday morning sessions. We thank you for trying out this new arrangement. We have also brought back the New Investigator and Post-Doctoral Competition Sessions, which were piloted at the Kyoto HBES and met with positive feedback. These joint sessions highlight the research of up-and-coming researchers in the field and enable the competition committees to select a winner by the Banquet Saturday night. Last, we have resurrected the computerized presentation timer (developed by Hasan Ayaz and first implemented at the 2006 HBES conference at Penn) to keep oral presentations synchronized.

There are many people who were critical to the success of this conference and we’d like to say a big thank you to them all. We are especially grateful to Shawn Lavoie of Experient, who was incredibly patient and helpful during our search for the HBES 2013 venue. We are also grateful to Billie Koperwas, who helped with developing all of the swag. We also thank the UM team of grad students for moral support and help with program details. A big thank you to Ray Hames for helping with the registration process and setting up accounts. Last, we would like to thank Brent Pocker for developing an awesome conference website and for maintaining the HBES database.

We are grateful for support from the University of Miami College of Arts and Sciences (Leonidas Bachas, Dean), UM Psychology Department (Rod Wellens, Chair), UM Department of Political Science (Jonathan West, Chair), and the Leonard and Jayne Abess Center for Ecosystem Science and Policy (Kenny Broad, Director).

We sincerely hope that your conference experience will be both personally enjoyable and intellectually enriching.

Debra Lieberman & Michael McCullough Conference Organizers

Table of Contents

Conference Overview 2 Schedule at a Glance

Program of Events 3 Wednesday 5 Thursday 12 Friday 19 Saturday

Abtracts 25 Poster 64 Keynote Address 65 Plenary Talks 68 Wednesday Afternoon Session Talks 74 Thursday Early Morning Session Talks 79 Thursday Late Morning Session Talks 84 Thursday Early Afternoon Session Talks 89 Thursday Late Afternoon Session Talks 94 Friday Early Morning Session Talks 99 Friday Late Morning Session Talks 104 Friday Early Afternoon Session Talks 109 Friday Late Afternoon Session Talks 114 Saturday Early Morning Session Talks 119 Saturday Late Morning Session Talks 124 Saturday Afternoon Session Talks

Competitions 131 New Investigator Talk Abstracts 132 Post-Doctoral Talk Abstracts

Authors 133 Index

Additional Information 140 HBES 2013 Committees 140 HBES Executive Council

Map of Venue: Inside Back Cover

1 Schedule at a Glance

WEDNESDAY, JULY 17 8:30AM – 11:00AM Publication Committee Meeting Sundial 11:30AM – 2:00PM Executive Committee Meeting Sundial 2:30PM – 4:00PM Plenary: Doug Kenrick Americana 3 4:00PM – 4:20PM Coffee Break Poinciana Foyer 4:20PM – 6:00PM Simultaneous Sessions Americana 1,2,3,4; Poinciana 3/4 6:00PM – 7:30PM Reception Americana Lawn 7:30PM – 8:30PM Plenary: Napoleon Chagnon Americana 3

THURSDAY, JULY 18 8:00AM – 8:30AM Coffee Poinciana Foyer 8:30AM – 10:00AM Plenary: Renée Baillargeon Americana 3 10:00AM – 10:20AM Coffee Break Poinciana Foyer 10:20AM – 11:20AM Early Morning Sessions Americana 1,2,3,4; Poinciana 3/4 11:20AM – 11:30AM Quick Break Poinciana Foyer 11:30AM – 12:30PM Late Morning Sessions Americana 1,2,3,4; Poinciana 3/4 12:30PM – 1:45PM Lunch On your own 1:45PM – 3:00PM Plenary: Brad Duchaine Americana 3 3:00PM – 3:20PM Coffee Break Poinciana Foyer 3:20PM – 4:40PM Early Afternoon Sessions Americana 1,2,3,4; Poinciana 3/4 4:40PM – 5:00PM Coffee Break Poinciana Foyer 5:00PM – 6:20PM Late Afternoon Sessions Americana 1,2,3,4; Poinciana 3/4 7:00PM – 7:30PM HBES Business Meeting Americana 3 7:30PM – 9:30PM Poster Session Americana Foyer

FRIDAY, JULY 19 8:00AM – 8:30AM Coffee Poinciana Foyer 8:30AM – 10:00AM Plenary: Melvin Konner Americana 3 10:00AM – 10:20AM Coffee Break Poinciana Foyer 10:20AM – 11:20AM Early Morning Sessions Americana 1,2,3,4; Poinciana 3/4 11:20AM – 11:30AM Quick Break Poinciana Foyer 11:30AM – 12:30PM Late Morning Sessions Americana 1,2,3,4; Poinciana 3/4 12:30PM – 1:45PM Lunch On your own 1:45PM – 3:00PM New Investigator Competition Americana 3 3:00PM – 3:10PM Quick Break Poinciana Foyer 3:10PM – 4:10PM Post Doctoral Competition Americana 3 4:10PM – 4:20PM Quick Break Poinciana Foyer 4:20PM – 5:40PM Early Afternoon Sessions Americana 1,2,3,4; Poinciana 3/4 5:40PM – 5:50PM Coffee Break Poinciana Foyer 5:50PM – 6:50PM Late Afternoon Sessions Americana 1,2,3,4; Poinciana 3/4 7:00PM – 9:00PM BBQ Americana Lawn

SATURDAY, JULY 20 8:00AM – 8:30AM Coffee Poinciana Foyer 8:30AM – 10:00AM Plenary: Peter Gray Americana 3 10:00AM – 10:20AM Coffee Break Poinciana Foyer 10:20AM – 11:20AM Early Morning Sessions Americana 1,2,3,4; Poinciana 3/4 11:20AM – 11:30AM Quick Break Poinciana Foyer 11:30AM – 12:30PM Later Morning Sessions Americana 1,2,3,4; Poinciana 3/4 12:30PM – 1:45PM Lunch On your own 1:45PM – 3:00PM Plenary: Redouan Bshary Americana 3 3:20PM – 5:20PM Afternoon Sessions Americana 1,2,3,4; Poinciana 3/4 6:00PM – 6:45PM Cocktail Reception Americana Foyer 6:45PM – 7:45PM Banquet Americana 3/4 7:45PM – 8:15PM Keynote Introduction: Steve Pinker Americana 3/4 8:15PM – 9:15PM Keynote Address: John Tooby & Leda Cosmides 2 WEDNESDAY, July 17

8:30-11:30 Publication Committee Meeting: Sundial, Breakfast 11:30-2:00 Executive Committee Meeting: Sundial, Lunch

Americana Salon 3 2:30-3:00 Welcome and Announcements 3:00-4:00 Plenary: Doug Kenrick The rational animal: Fundamental motives and behavioral economics

4:00-4:20 Coffee Break, Poinciana Foyer

AFTERNOON SESSION

Americana Salon 1 Symposium: Misconceptions about human social evolution Symposium Organizer: Claire El Mouden 4:20 Public Goods Games do not provide evidence for pro-social preferences Max Burton-Chellew, Stu West 4:40 Common misconceptions about the evolutionary explanations for behavior in economic games Claire El Mouden 5:00 Kin and group selection describe the same process: natural selection Geoff Wild 5:20 You’d better not treat ME that way! Third party punishment may not be what you thought Max M. Krasnow, Andrew W. Delton, Leda Cosmides, John Tooby 5:40 Punishment and the evolution of group cooperation in the absence of higher-order selection Andrew W. Delton, Max M. Krasnow, Leda Cosmides, John Tooby

Americana Salon 2 Symposium: Political decision-making Symposium Organizer: Casey Klofstad 4:20 Candidate voice pitch influences voters Casey Klofstad 4:40 The behavioral immune system and anti-immigration attitudes: Individual differences related to disgust shape opposition to immigration Lene Aarøe, Michael Bang Petersen, Kevin Arceneaux 5:00 Facial dominance predicts candidates’ political positions, candidates’ electoral success and parties’ nomination strategies Lasse Laustsen, Michael Bang Petersen, Israel Waismel-Manor 5:20 Birth weight influences social and political orientations under current stress Michael Bang Petersen, Lene Aarøe 5:40 Coalitional psychology and international politics Anthony Lopez

3 WEDNESDAY, July 17

Americana Salon 3 Symposium: The evolution of social cognitive development Symposium Organizer: Annie Wertz 4:20 Evolved social learning mechanisms for the botanical world Annie Wertz, Karen Wynn 4:40 Infants’ use of confidence and competence cues in social learning Vivan Lee, M.D. Rutherford 5:00 Moral judgment and action in preverbal infants and toddlers: Evidence for a reliably developing moral core J. Kiley Hamlin 5:20 Coalitional psychology on the playground: Reasoning about indirect social consequences in preschoolers and adults David Pietraszewski 5:40 Specialized mechanisms for theory of mind: Are mental representations special because they are mental or because they are representations? Adam S. Cohen, Tamsin C. German

Americana Salon 4 Symposium: Current directions in the evolutionary study of humor and laughter Symposium Organizer: Thomas Flamson 4:20 Encryption and Individual Differences in Sense of Humor Thomas Flamson, Clark Barrett 4:40 Identifying in-group and self-deception: What both scientists and comedians have to say about the evolutionary function of humor and what is funny Robert Lynch 5:00 Humor as a mental fitness indicator: Different jokes for different goals Christopher Wilbur 5:20 Gender differences in the effects of relationship satisfaction and self-perceived physical attractiveness on humor ability in long-term relationships Melanie Beaussart, Scott Kaufman, James Kaufman 5:40 Humor quality, attractiveness, and person perception Eric Bressler, Sigal Balshine

Poinciana 3/4 Culture I: Kinship and social learning 4:20 Kinship cues and demographic transition: The evolutionary origin of mass ideologies Tamas David-Barrett, Robin Dunbar 4:40 An East-West comparison of learning strategies: Chinese and British participants show equally sub-optimally low rates of social learning Alex Mesoudi, Keelin Murray, Lei Chang 5:00 Information sharing strategies: What drives the transmission of information? Maxime Derex, Bernard Godelle, Michel Raymond 5:20 Social learning in the cooperative domain Shakti Lamba

4 WEDNESDAY, July 17

6:00-7:30 Reception, Americana Lawn

Americana Salon 3 7:30-8:30 Plenary: Napoleon Chagnon Grandmothers and grandfathers among the Yanomamö

THURSDAY, July 18

8:00-8:30 Coffee Break, Poinciana Foyer

Americana Salon 3 8:30-9:00 Announcements and Introduction 9:00-10:00 Plenary: Renée Baillargeon Early sociomoral reasoning

10:00-10:20 Coffee Break, Poinciana Foyer

EARLY MORNING SESSION

Americana Salon 1 Signaling I 10:20 Preferences for vocal masculinity in male and female leaders are context-dependent Cara Tigue, Paul J Fraccaro, Jillian O’Connor, Katarzyna Pisanski, David Feinberg 10:40 Low-pitched male voices elicit anger from men: Evidence for the retaliation-cost hypothesis of aggressive intention signaling in humans Jinguang Zhang, Scott Reid 11:00 A meta-analysis of voice and body size relationships Katarzyna Pisanski, Paul Fraccaro, Cara Tigue, Jillian O’Connor, Susanne Röder, Lisa DeBruine, Ben Jones, Bernhard Fink, Paul Andrews, David Feinberg

Americana Salon 2 Aggression I 10:20 Is adolescent bullying an evolutionary adaptation? Anthony Volk, Joseph Camilleri, Andrew Dane, Zopito Marini 10:40 Divide and conquer: When and why leaders create divisions between their subordinates Charleen Case, Jon Maner 11:00 Coalitional persecution of immigrants is motivated by dominance-boundary enforcement Lotte Thomsen, Siri Leknes

5 THURSDAY, July 18

EARLY MORNING SESSION

Americana Salon 3 Symposium: Evolutionary economics and decision-making Symposium Organizer: Vladas Griskevicius 10:20 Uncovering mechanisms for near-optimal exploration and exploitation in resource search Peter Todd, Ke Sang, Joaquin Goñi 10:40 From the bedroom to the budget deficit: mate competition changes men’s attitudes toward economic redistribution Andrew White, Douglas Kenrick, Rebecca Neel, Steven Neuberg 11:00 Spending on boys versus girls in economic recessions: Experimental evidence for the Trivers- Willard hypothesis Joseph Redden, Kristina Durante, Vladas Griskevicius, Andrew White

Americana Salon 4 Menstrual Cycle I 10:20 Women’s psychology of resource-based opposite-sex friendships Diana Fleischman, Carin Perilloux, David Buss 10:40 Do hormonal contraceptives alter women’s mate choice and relationship functioning? Hypothesized mechanisms of action Christina Larson, Martie Haselton 11:00 Hormonal predictors of women's sexual motivation James Roney, Zachary Simmons

Poinciana 3/4 Cooperation I 10:20 Social networks of the Ifugao rice farmers Charan Chaudhary, Andrea Migliano 10:40 A new perspective on the evolution of human cooperation Emily Wyman 11:00 Testing theories about ethnic markers: Ingroup dialect facilitates coordination, not cooperation Niels Holm Jensen, Michael Bang Petersen, Henrik Høgh-Olesen, Michael Ejstrup

11:20-11:30 Quick Coffee Break, Poinciana Foyer

6 THURSDAY, July 18

LATE MORNING SESSION

Americana Salon 1 Signaling II 11:30 Costly signals and cooperation in structured interaction Károly Takács, András Németh 11:50 Until death don't us part: Grief as a hard-to-fake signal of commitment Bo Winegard, Tania Reynolds 12:10 TBD TBD

Americana Salon 2 Aggression II 11:30 Are men more aggressive when mates are plentiful or scarce? A natural experiment in the outer islands of Yap Emily A Stone 11:50 Adult male scarcity predicts adolescent violence at the neighborhood level Daniel Kruger, Sophie Aiyer, Marc Zimmerman 12:10 Too many men: The violence problem? Ryan Schacht, Kristin Rauch, Monique Borgerhoff Mulder

Americana Salon 3 Mating I 11:30 Casual sexual relations: Illuminating sexually dimorphic motivations and emotional reactions John Marshall Townsend 11:50 Sexual misperception among Norwegian students Mons Bendixen 12:10 Sexual misperception revisited – evidence that men are accurate Carin Perilloux, Robert Kurzban

Americana Salon 4 Menstrual Cycle II 11:30 Oral contraceptive use and the motivational salience of infant facial cuteness Amanda Hahn, Claire Fisher, Lisa DeBruine, Reiner Sprengelmeyer, David Perrett, Ben Jones 11:50 Physiological changes in response to hearing female voices recorded at high and low fertility Melanie Shoup-Knox, R Nathan Pipitone 12:10 Men perceive their female partners, and themselves, as more attractive around ovulation Kelly D Cobey, Abraham Buunk, Thomas Pollet, Christine Klipping, S Craig Roberts

7 THURSDAY, July 18

LATE MORNING SESSION

Poinciana 3/4 Cooperation II 11:30 Facial traits influence proposer behaviour in cross-cultural ultimatum games Poppy Mulvaney, Ian Penton-Voak 11:50 High fitness features influence cooperative behavior in women Enrique Turiegano, Jose Antonio Muñoz-Reyes, Miguel Pita, María Arjona, Santiago Sanchez- Pages 12:10 Prestige and punishment: Only dominant individuals can enforce a ‘credible threat’ of third party punishment David S Gordon, Stephen Lea, Joah Madden

12:30-1:45 LUNCH (on your own)

Americana Salon 3 1:45-2:00 Announcements and Introduction 2:00-3:00 Plenary: Brad Duchaine Investigating face processing through deficits and disruptions

3:00-3:20 Coffee Break, Poinciana Foyer

EARLY AFTERNOON SESSION

Americana Salon 1 Cooperation III 3:20 Two types of within-group competition affect cooperation in social groups Jessica Barker, Pat Barclay, Kern Reeve 3:40 The joint emergence of costly between-group conflict and within-group cooperation Mikael Puurtinen, Tapio Mappes 4:00 “Us vs. Them” or “Us vs. Nature”: Cooperation and manipulation in response to social and asocial group threats Pat Barclay, Stephen Benard 4:20 Being there: A brief visit to a low-trust neighborhood rapidly evokes low trust Daniel Nettle, Gillian Pepper, Kari Britt Schroeder

Americana Salon 2 Symposium: Validating self-report life history measures Symposium Organizer: Pedro Sofio Abril Wolf 3:20 Sleep, physical activity, affect, and life history strategy: a multi-measure, multi-predictor study Pedro Wolf, Kirsten Clacey, Candice Edmunds 3:40 Comparing hypotheses of assortative mating Sally Olderback, Pedro Wolf, Aurelio José Figueredo 4:00 The behavioral correlates of overall and distinctive life history strategy Ryne Sherman, Aurelio José Figueredo, David Funder 4:20 Life history status predicts the form and success of sexual strategies in college-age men & women Tarah Swanepoel, Pedro Wolf, Kevin Thomas 8

THURSDAY, July 18

EARLY AFTERNOON SESSION

Americana Salon 3 Morality and the Law 3:20 Why humans (especially simple foragers) are so egalitarian Frank Marlowe 3:40 Female economic dependence and the morality of promiscuity Michael Price, Nicholas Pound, Isabel Scott 4:00 People’s ownership intuitions about disputes between finders and landowners Peter DeScioli 4:20 Relative morality: Influences of social relationship on moral decision making Meaghan Altman

Americana Salon 4 Kinship I 3:20 Genetically unrelated look-alike individuals: Novel tests of social closeness & personality similarity Nancy L Segal, Jamie L Graham, Ulrich Ettinger 3:40 An expanded concept of kin recognition by phenotype matching Daniel Krupp, Peter Taylor 4:00 Evidence for specialized processing of facial kinship cues Lisa DeBruine, Benedict Jones, Debra Lieberman, Craig Roberts 4:20 Should I stay or should my siblings go? Sibship effects on dispersal behaviour Aïda Nitsch, Charlotte Faurie, Virpi Lummaa

Poinciana 3/4 Mating II 3:20 Men’s, but not women’s, sociosexual orientation predicts couples’ perceptions of sexually dimorphic cues in own-sex faces Michal Kandrik, Corey Fincher, Benedict Jones, Lisa DeBruine 3:40 A cross-cultural confirmation of sex difference of responses to imagining a partner’s heterosexual or homosexual affair Mark Cloud, Stephanie De Jesus 4:00 Effects of paternal age & early development conditions on attractiveness and number of children Martin Fieder, Susanne Huber 4:20 Seasonal changes in testosterone levels and body composition among rural Polish men Louis Calistro Alvarado, Melissa Emery Thompson, Magdalena Klimek, Martin N Muller, Ilona Nenko, Grazyna Jasien

4:40-5:00 Coffee Break, Poinciana Foyer

9

THURSDAY, July 18

LATE AFTERNOON SESSION

Americana Salon 1 Cooperation IV 5:00 Preferential interaction and large-scale cooperation: The issue of perspective switching Jun-Hong Kim, Darryl Holman, Steven Goodreau 5:20 Gossip, reputation and sharing in Central African foragers Nicole Hess, Edward Hagen 5:40 Trust dynamics in the social construction of cooperation: An empirical analysis Cristina Acedo Carmona, Antoni Gomila Benejam 6:00 Why do people selectively give benefits to cooperators in SD? Nobuyuki Takahashi, Misato Inaba

Americana Salon 2 Aggression III 5:00 Representations of relative formidability and social cognition Daniel Fessler, Colin Holbrook, Jeremy Pollack, Jennifer Hahn-Holbrook 5:20 Resource conflict and the asymmetric war of attrition in children Alex Shaw, David Pietraszewski 5:40 Face of a fighter: Bizygomatic width as a cue of formidability Samuele Zilioli, Aaron Sell, Neil Watson 6:00 The importance of physical strength to human males Aaron Sell

Americana Salon 3 Symposium: The impact of life history strategies on perceptions, psychopathology, and menarche: Experimental and longitudinal evidence Symposium Organizers: Chiraag Mittal and Jeffry A. Simpson 5:00 Harshness, unpredictability, and age of menarche: A life history approach Jeffry A Simpson, Vladas Griskvicius, Sooyeon Sung, Sally I Kuo 5:20 Fat, fertility, & fast strategies: The effect of ecological harshness on the ideal female body size Sarah E Hill, Danielle DelPriore, Christopher D Rodeheffer, Max Butterfield 5:40 Evolutionary psychopathology: A unifying life history framework Marco Del Giudice 6:00 Psychological drivers of fast and slow life history strategies: The sense of personal control Chiraag Mittal, Vladas Griskevicius

10

THURSDAY, July 18

LATE AFTERNOON SESSION

Americana Salon 4 Kinship II 5:00 Effects of sex and relatedness on levels of sibling conflict Catherine Salmon, Jessica Hehman 5:20 Kin investment by stepgrandparents: More than expected Alexander Pashos, Sascha Schwarz, Donald H McBurney, David F Bjorklund 5:40 Maternal kin take on the care of children in more challenging circumstances than paternal kin Gretchen Perry, Martin Daly 6:00 Reproductive competition and co-operation between siblings in the matrilineal Mosuo of southwestern China Ruth Mace, Ting Ji, Jia-Jia Wu, Qiao-Qiao He, Jingjing Xu, Yi Tao

Poinciana 3/4 Culture: Language 5:00 Optimal investment in reputation: A prejudist's approach Alexander Funcke 5:20 Tracing human cultural ancestry in time and space Quentin Atkinson 5:40 On the role of analogy in cultural transmission and human dispersal Marshall Abrams 6:00 The extent of combinatorial communication in nature, and its relevance for the origins of language Thom Scott-Phillips, James Gurney, Al Ivens, Stephen Diggle, Roman Popat

7:00-7:30 HBES Business Meeting, Americana 3

7:30-9:30 POSTER SESSION, Americana Foyer

11

FRIDAY, July 19

8:00-8:30 Coffee Break, Poinciana Foyer

Americana Salon 3 8:30-9:00 Announcements and Introduction 9:00-10:00 Plenary: Mel Konner Hunter-gatherer infancy and childhood in the context of human life history evolution

10:00-10:20 Coffee Break, Poinciana Foyer

EARLY MORNING SESSION

Americana Salon 1 Life History I 10:20 The impact of sex ratio and economic status on local birth rates Abby Chipman, Edward Morrison 10:40 Socio-demographic influences on sex ratio at birth (SRB): A comparative study Bernard Wallner 11:00 Wealth inequality, social capital, health, and life history strategy in Tsimane forager- horticulturalists Aaron Blackwell, Adrian Jaeggi, Jonathan Stieglitz, Paul Hooper, Hillard Kaplan, Michael Gurven

Americana Salon 2 Cooperation V 10:20 Do social preferences drive biologically altruistic behavior? Alejandro Rosas 10:40 The effect of power asymmetries on cooperation and punishment in humans Jonathan Bone, Nichola Raihani 11:00 Possible roles for punishment and reward from an evolutionary perspective Jennifer Jacquet

Americana Salon 3 Symposium: Evolutionary medicine: A survey of important advances in the field Symposium Organizer: Paul Andrews 10:20 Alzheimer’s Disease and the evolution of longevity Molly Fox 10:40 Sugar and ice and everything nice: An evolutionary approach to age and sex differences in substance use Edward Hagen, Casey Roulette, Roger Sullivan 11:00 On the function of placental corticotropin-releasing hormone: a role in maternal-fetal conflicts over blood glucose concentrations Steven Gangestad, Ann Caldwell-Hooper, Melissa Eaton

12

FRIDAY, July 19

EARLY MORNING SESSION

Americana Salon 4 Emotion I 10:20 Status, individual differences, and emotional reactions to threat Beatrice Alba, Doris McIlwain 10:40 Shades of green: The functional distinction between benign and hostile envy Rachel Falcon 11:00 Gratitude and interpersonal welfare valuation Adam Smith, Debra Lieberman, Eric Pedersen, Daniel Forster, Michael McCullough

Poinciana 3/4 Symposium: Facing challenges and evolutionary happiness in Latin America Symposium Organizer: Jorge Yamamoto 10:20 Migration from a traditional Inca´s village to a modern city: Changes in goals, resources, and its well-being correlates Cinthya Diaz 10:40 Decision to get pregnant and subjective well-being improvement in adolescent mothers in extreme poverty in Peru: An adaptive strategy, not an accident Brenda Chavez 11:00 Adaptation and values change: Modernization and unhappiness in rural fishermen village in Peru Dante Solano

11:20-11:30 Quick Coffee Break, Poinciana Foyer

LATE MORNING SESSION

Americana Salon 1 Life History II 11:30 Father absence and age at first birth: What can a review of the cross-cultural evidence tell us about what fathers do for their children? Rebecca Sear, David Coall 11:50 Fostering relations: the differences in sexual and reproductive outcomes between children raised by kin and non-kin carers Susan Schaffnit, Paula Sheppard, Justin Garcia, Rebecca Sear 12:10 Early life adversity does not accelerate menarche in the Dogon of Mali Beverly Strassmann

13

FRIDAY, July 19

LATE MORNING SESSION

Americana Salon 2 Cooperation VI 11:30 Conditional punishment depends not only on how it affects free riders but also how fellow cooperators act Sangin Kim, John Tooby, Leda Cosmides 11:50 Incompetent, disabled, and unlucky: Specialization for distinguishing and tracking functionally distinct causes of non-contributions Theresa Robertson, Andrew Delton 12:10 Do humans really punish altruistically? A closer look Eric J Pedersen, Robert Kurzban, Michael McCullough

Americana Salon 3 Symposium (cont.): Evolutionary medicine: A survey of important advances in the field Symposium Organizer: Paul Andrews 11:30 The impact of social stress on women’s health & fertility: An evolutionary life history perspective Athena Aktipis 11:50 Hormones in the wild: Why psychosocial stress can make us sick Mark Flinn 12:10 Population level effects of suppressing fever Paul Andrews, David Earn, Ben Bolker

Americana Salon 4 Emotion II 11:30 Common knowledge and the self-conscious emotions Kyle Thomas, Steven Pinker 11:50 Towards an evolutionary psychology of attitudes: Affective representations moderate social emotions and behavior in Fiji Matthew Gervais, Daniel Fessler 12:10 Conceptual and empirical challenges to the “authentic” versus “hubristic” model of pride Colin Holbrook, Jared Piazza, Daniel Fessler

Poinciana 3/4 Symposium (cont.): Facing challenges and evolutionary happiness in Latin America Symposium Organizer: Jorge Yamamoto 11:30 Why and how local institutions weaken, fall and rise in the context of political violence Carlos Aramburu 11:50 Five clusters of values: shades from altruists to cheaters Sebastian Wendorff 12:10 Facing challenges and Latin American happiness from an evolutionary perspective Jorge Yamamoto

12:30-1:45 LUNCH (on your own) 14 FRIDAY, July 19

Americana Salon 3 1:45-2:00 Announcements

Americana Salon 3 New Investigator Competition Finalists 2:00 Meta-analytic review of cycle shifts in women's mate preferences: Findings from complete set of 72 published and unpublished effects Kelly Gildersleeve, Department of Psychology, UCLA Co-authors: Melissa Fales, Martie Haselton 2:20 How to learn about teaching: An evolutionary framework and empirical tests from Fiji Michelle Ann Kline, Department of Anthropology, UCLA Co-authors: Robert Boyd, Joseph Henrich 2:40 Spatial visualization predicts range size and reproductive success among the Namibian Twe and Tjimba Layne Vashro, Department of Anthropology, University of Utah Co-authors: Elizabeth Cashdan

Americana Salon 3 Post Doctoral Competition Finalists 3:10 A mutualistic approach to morality: The evolution of fairness by partner choice Nicolas Baumard, Philosophy, Politics and Economics Program, University of Pennsylvania Co-authors: Jean-Baptiste André, Dan Sperber 3:30 When the economy falters do people spend or save? Responses to resource scarcity depend on childhood environments Vladas Griskevicius, Business School, University of Minnesota Co-authors: Joshua Ackerman, Stephanie Cantú, Andrew Delton, Theresa Robertson, Jeffry Simpson, Melissa Emery Thompson, Josh Tybur 3:50 Evolution of cooperation among mammalian carnivores and its relevance to hominin evolution Jennifer E Smith, Department of Biology, Mills College Co-authors: Eli M Swanson, Daphna Reed, Kay E Holekamp

4:10-4:20 Coffee Break, Poinciana Foyer

EARLY AFTERNOON SESSION

Americana Salon 1 Emotion III 4:20 Disgust sensitivity, personality, and evolutionary perspectives on individual differences Joshua Tybur 4:40 Behavioral evidence that pathogen disgust functions as a contagion avoidance mechanism Corey Fincher, Amanda Hahn, Claire Fisher, Benedict Jones, Lisa DeBruine 5:00 Measuring “moral contagion”: Perceptions of moral character modulate physical distancing responses Hillary Lenfesty 5:20 Infectious disease, values, IQ, and the wealth of nations Randy Thornhill, Corey Fincher

15 FRIDAY, July 19

EARLY AFTERNOON SESSION

Americana Salon 2 Symposium: Strategic and cognitive differentiation and integration as a function of life history strategy Symposium Organizer: Aurelio José Figueredo 4:20 Multiple successful tests of the strategic differentiation-integration effort (SD-IE) hypothesis Aurelio José Figueredo, Michael A Woodley, Kari Celeste Ross, Sacha D Brown 4:40 Strategic allocation of cognitive abilities: A look at life history’s role in cognitive differentiation and integration Rafael A Garcia, Tomas Cabeza de Baca, Christopher J Wenner, Kari Celeste Ross, Sacha D Brown, Aurelio José Figueredo 5:00 Strategic differentiation-integration effort in the context of sexual strategies: A cross-national perspective Heitor Fernandes, Michael A Woodley, Claudio Hutz, Daniel Kruger 5:20 Cognitive differentiation-integration effort in developmental perspective Michael A Woodley, Curtis Dunkel, Aurelio José Figueredo

Americana Salon 3 Cognition I 4:20 Back to the drawing board: Computational-evolutionary revisitations of some early work in psychology Jason Wilkes 4:40 The ecological rationality of intertemporal choice in humans Evan Carter, Eric Pedersen, Michael McCullough 5:00 A game of hide and seek: Expectations of clumpy resources influence hiding and searching patterns in a sequential multi-person game Andreas Wilke, Steven Minich, Megane Panis, Tom Langen, Peter Todd 5:20 Sequential decision making and illusionary pattern detection in gamblers Paige McCanney, Aisha Wood, Amanda Sherman, Benjamin Scheibehenne, Wolfgang Gaissmaier, Clark Barrett, Andreas Wilke

Americana Salon 4 Attractiveness I 4:20 Visual, olfactory, and vocal cues to women’s reproductive value Susanne Röder, Bernhard Fink 4:40 You had me at hello: Acoustic correlates of thin slice judgments of women’s vocal attractiveness Greg Bryant, Martie Haselton, Elizabeth Pillsworth 5:00 Facial coloration and the behavioral immune system Benedict Jones, Amanda Hahn, Claire Fisher, Corey Fincher, Carmen Lefevre, Ross Whitehead, Michal Kandrik, David Perrett, Anthony Little, Craig Roberts, Lisa DeBruine 5:20 Predicting health from facial shape: A geometric morphometric modeling study Ian Stephen, Vivian Hiew

16

FRIDAY, July 19

EARLY AFTERNOON SESSION

Poinciana 3/4 Cooperation VII 4:20 Natural recreation of a dictator game reveals no altruism Jeffrey Winking 4:40 Evolution of fairness in the one-shot anonymous Ultimatum Game Hisashi Ohtsuki, David Rand, Corina Tarnita, Martin Nowak 5:00 The evolution of merit by partner choice Stéphane Debove, Nicolas Baumard, Jean-Baptiste André 5:20 Effect of limited resources on the dynamics of cooperation under indirect reciprocity Sayaka Ishihara, Hisashi Ohtsuki, Toshikazu Hasegawa

5:40-5:50 Quick Coffee Break, Poinciana Foyer

LATE AFTERNOON SESSION

Americana Salon 1 Emotion IV 5:50 “Hows” and “whats” inform the “whys”: Evolution, development, and the emergence of disgust Joshua Rottman, Peter Blake 6:10 Unfamiliar religious groups are perceived as more different to people who are disgusted by pathogens (but not by sex or morality) Scott Reid, Grace Anderson, Jinguang Zhang, Jessica Gasiorek, Marko Dragojevic, Susana Peinado, Becky Robinson 6:30 Understanding sexual prejudices: Avoiding threats of unwanted sexual interest? Angela Pirlott, Steven Neuberg

Americana Salon 2 Individual Differences I 5:50 The mating/parenting trade-off: Short-term mating orientation and mate value predict less nurturing emotional responses toward infants Alec T Beall, Mark Schaller 6:10 Exploring sex differences in color preference using online resources Casey McGlasson, Jared Lorince, David Crandall, Peter Todd 6:30 Sex differences in conformity: Confidence as a proximate psychological mechanism Catharine Cross, Gillian Brown, Thomas Morgan, Kevin Laland

17

FRIDAY, July 19

LATE AFTERNOON SESSION

Americana Salon 3 Cognition II 5:50 Power on my side: A coalitional psychology approach to the vicarious experience of power Jennifer Sheehy-Skeffington, James Sidanius 6:10 Does valence modulate source memory? Laurence Fiddick, David Mitchell 6:30

Americana Salon 4 Attractiveness II 5:50 Genetic analysis of male and female twins does not support ‘indirect benefits’ account of masculine male face shape Brendan Zietsch, Anthony Lee, Dorian Mitchem, Margaret Wright, Nicholas Martin, Matthew Keller 6:10 On the modulatory effects of cortisol on associations of testosterone with male attractiveness, facial masculinity and health Nicholas Grebe, Steven Gangestad 6:30 Cross-cultural comparison of female perception of male dance movements Bernhard Fink, Bettina Weege, Nick Neave, Bettina Ried, Olival C do Lago

Poinciana 3/4 Life History III 5:50 The effects of early childhood environmental uncertainties on adolescents’ risk taking attitude and behavior: A life history analysis Jing Wu, Lei Chang 6:10 Infant and child death in the human environment of evolutionary adaptation Jeremy Atkinson, Anthony Volk 6:30 The influence of past and present living environments: Are current risk assessments shaped by the dangers of our childhood environment? Amanda Sherman, Steven Minich, Tom Langen, Joseph Skufca, Andreas Wilke

7:00-9:00 BBQ, Americana Lawn

18

SATURDAY, July 20

8:00-8:30 Coffee Break, Poinciana Foyer

Americana Salon 3 8:30-9:00 Announcements and Introduction 9:00-10:00 Plenary: Peter Gray The evolutionary biology of education: Children’s educative instincts can work well today

10:00-10:20 Coffee Break, Poinciana Foyer

EARLY MORNING SESSION

Americana Salon 1 Cognition III 10:20 Effects of foraging related stimuli on object location memory and perceptual search in the hunter-gatherer theory Espen Sjoberg, Geoff Cole, Luke Cannon 10:40 Attentional basis of deontic reasoning in 3-5 year-old children: A test of social-contract and hazard-management theories Patrick Sellers II, Kayla Causey, David Bjorklund 11:00 Powerful poses: Not necessary and not sufficient to produce feelings of power Melissa McDonald, Joseph Cesario

Americana Salon 2 Culture II 10:20 Class conflict and conciliation in evolutionary perspective: The German case, 1900 to 2000 David Meskill 10:40 Parsing within-group determinants of fertility decline in two horticulturalist populations Anne Pisor 11:00 An exploration of exploitation: Children’s religious acquisition Viviana Weekes-Shackelford, Todd Shackelford, Yael Sela, Alyse Ehrke, John Arvanitis

Americana Salon 3 Symposium: Evolutionary analyses of crime and punishment Symposium Organizer: David Buss, Vibeke Ottesen 10:20 The evolutionary psychology of crime David Buss 10:40 Adaptations and nonadaptations to violence & nonviolence Steven Pinker 11:00 Is it really inequality that drives variability in homicide rates? Martin Daly

19

SATURDAY, July 20

EARLY MORNING SESSION

Americana Salon 4 Individual Differences II 10:20 Masters track participation in U.S. reveals a stable sex difference in competitiveness Robert Deaner, Vittorio Adonna, Michael Mead 10:40 Broad face co-occurs with ankle morphology good for speedy sprinting and efficiency in long- distance running Gordon Bear, Jeremy Atkinson, Leslie Migliaccio, Jovan Naidoo 11:00 Navigational skills and multisensory calibration reflect individual differences in environmental distance perception Chela Willey, Russell Jackson

Poinciana 3/4 Phylogenetics 10:20 Food sharing and reciprocal altruism in humans and other primates: A phylogenetic meta- analysis Adrian Jaeggi, Michael Gurven 10:40 Detailed reconstruction of ancestral human and hominid behaviors using phylogenetic comparative methods Pavel Duda, Jan Zrzavý 11:00 Do metabolic tradeoffs explain why humans have exceptionally large brains? Testing the expensive tissue hypothesis using phylogenetic analysis Amy Boddy, Athena Aktipis, Chet Sherwood, Lawrence Grossman, Derek Wildman

11:20-11:30 Quick Coffee Break, Poinciana Foyer

LATE MORNING SESSION

Americana Salon 1 Symposium: Women’s sexual behavior: Causes, constraints, and context Symposium Organizer: Kristina Durante 11:30 The effects of paternal disengagement cues on women's sexual thoughts and perceptions Danielle DelPriore, Sarah Hill 11:50 Fertile and flirty: Ovulation changes women’s behavior toward men Stephanie Cantu, Jeffry Simpson, Vladas Griskevicius, Yanna Weisberg, Kristina Durante, Daniel Beal 12:10 The fluctuating female vote: Politics, religion, and the ovulatory cycle Kristina Durante, Ashley Rae, Vladas Griskevicius

20 SATURDAY, July 20

LATE MORNING SESSION

Americana Salon 2 Culture III 11:30 Cumulative culture in the laboratory: You need more models, if the task is hard Michael Muthukrishna, Ben Shulman, Vlad Vasilescu, Joseph Henrich 11:50 Stick to the script: The effect of witnessing multiple actors on children’s imitation Christine Legare 12:10 Cultural evolution and model-based biases: Reading behavioral cues of performance Helen Wasielewski

Americana Salon 3 Symposium (cont.): Evolutionary analyses of crime and punishment Symposium Organizer: David Buss, Vibeke Ottesen 11:30 Can principles of parental investment predict patterns of child homicide in Norway? Vibeke Ottesen 11:50 Darwin on the witness stand: Evolutionary psychology, forensic evaluations, and expert testimony J Andy Thompson 12:10 Moderated Discussion David Buss

Americana Salon 4 Individual Differences III 11:30 Men’s testosterone and exposure to competitive others across their partners’ ovulatory cycle: A test of the challenge hypothesis in men Melissa Fales, Kelly Gildersleeve, Martie Haselton 11:50 Risk-taking and sexual promiscuity in night owls: Is eveningness an adaptation for short-term mating? Dario Maestripieri 12:10 Are risk-persistent individuals adaptive decision-makers? Sandeep Mishra, Martin Lalumiere

Poinciana 3/4 Applied Evolutionary Psychology 11:30 Is postpartum depression a disease of modern civilization? Jennifer Hahn-Holbrook, Martie Haselton, Christine Dunkel Schetter 11:50 Danger in the eye of the beholder: Discovery of the plateau illusion tests behavioral evolution criticisms Russell Jackson, Chéla Willey 12:10 Enhancing knowledge about and positive attitudes toward evolutionary theory: Curricular effectiveness as measured by the Evolutionary Attitudes and Literacy Survey (EALS) Patricia H Hawley, Stephen D Short

12:30-1:45 LUNCH (on your own)

21 SATURDAY, July 20

Americana Salon 3 1:45-2:00 Announcements and Introduction 2:00-3:00 Plenary: Redouan Bshary What game theory applied to cleaning mutualism may tell us about links between cooperation and cognition

3:00-3:20 Coffee Break, Poinciana Foyer

AFTERNOON SESSION

Americana Salon 1 Cooperation VIII 3:20 Human punishment is motivated by inequity aversion not a desire for reciprocity Nichola Raihani, Katherine McAuliffe 3:40 Social influences on inequity aversion in children Katherine McAuliffe, Peter Blake, Grace Kim, Richard Wrangham, Felix Warneken 4:00 Cooperative behavior in school children: The influence of vigilance, positive and negative feedback Maria Emilia Yamamoto, Natalia Dutra, Natalia Boccardi, Phietica Silva, Anuska Alencar 4:20 Development and transmission of costly punishment in children Gul Deniz Salali, Myriam Juda, Joseph Henrich 4:40 Cognitive adaptations for the delivery of information: The case of spontaneous confession to a victim Daniel Sznycer, Eric Schniter, John Tooby, Leda Cosmides 5:00 Social cognition and food sharing: A study of tolerated scrounging and feeding Thomas Alley

Americana Salon 2 Mating III 3:20 Sexual strategies during pregnancy Jaclyn Ross, Elizabeth Pillsworth 3:40 Changes in mate preferences and selectivity across age cohorts David Frederick, Kelly Gildersleeve 4:00 The relationship between objective risk of sperm competition and men’s copulatory interest in their partner is moderated by the amount of time their partner spends with other men Michael Pham, Todd Shackelford 4:20 Sperm competition risk moderates the link between men’s relationship investment and interest in their partner’s copulatory orgasm Todd Shackelford, William McKibbin, Vincent Bates, Christopher Hafen, Craig LaMunyon 4:40 Psychological sex differences across cultures: Why biosocial theory explains so little David Schmitt 5:00 TBD

22 SATURDAY, July 20

AFTERNOON SESSION

Americana Salon 3 Symposium: Cognition, contagion, and consumption: Darwinian decision-making in the marketplace and beyond Symposium Organizer: Sarah Hill 3:20 The who, when, and why of human mate choice copying: Attractive women provide a proxy for male quality Christopher Rodeheffer, Sarah Hill, Holly Pettijohn, Megan Osborne, Leah Colburn, Tia Robb 3:40 The effect of ovulation on women's variety seeking: From playing it safe to playing the field Ashley Rae, Kristina Durante 4:00 Fendi handbags fend off romantic rivals: Women's conspicuous consumption as a signaling system Yajin Wang, Vladas Griskevicius 4:20 The clothes and the man: Authenticity matters in clothing for men T Andrew Poehlman, Joshua Ackerman

Americana Salon 4 Kinship, Sex, and Orgasm 3:20 Covariates and outcomes of child fostering in two rural Timor-Leste communities Debra Judge, Katherine Sanders 3:40 Family structure, rural livelihoods and child health inequality in Tanzania David Lawson, Monique Borgerhoff Mulder, Margherita Ghiselli, Esther Ngadaya, Bernard Ngowi, Sayoki Mfinanga, Kari Hartwig, Susan James 4:00 Factors predicting the probability of women initiating sex in relationships Leif Edward Ottesen Kennair, Mehmet Mehmetoglu, Trond Viggo Grøntvedt 4:20 Vaginal orgasm as a cryptic female choice system: Selection for penis size and copulatory vigor Geoffrey Miller

Poinciana 3/4 Life History IV 3:20 Inter-generational conflicts over reproductive decisions: A cross-cultural examination of parental presence effects on fitness Cristina Moya, Rebecca Sear 3:40 The interplay of individual- and community-level postnuptial residence on fertility outcomes: Do community norms or individual decisions matter more? Kristin Snopkowski, Rebecca Sear 4:00 It’s all in the timing: Opposite effects of childhood and young adulthood psychosocial stress on reproductive timing in Australian women David Coall, James Chisholm 4:20 What a girl wants: Does childhood adversity fast track desired reproductive timing and increase interest in infants in peripubescent girls? Stephanie Clutterbuck, Daniel Nettle, Jean Adams 4:40 Early childhood and current life uncertainties predict human female mating strategies Xiaoqin Zhu, Lei Chang 5:00 Do life-history strategies and mating orientations translate into desires for children? Gary Brase 23 SATURDAY, July 20

6:00-6:45 Cocktail Reception, Americana Foyer

6:45-7:45 Banquet, Americana Salon 3/4

7:30-8:00 Keynote Introduction: Steven Pinker John and Leda: An Appreciation

8:00-9:00 Keynote: John Tooby and Leda Cosmides Evolutionary psychology: Back to the future

24 Poster Abstracts

Aggression

1 The emergence of despotism or egalitarianism due to simple heuristics and variation in personality types Jeremy Auerbach, University of Tennessee, [email protected] The emergence and maintenance of despotism been explored from various perspectives, such as population densities or resource abundance. Here we allow for social stratification to be determined by variation in personality types. Aggressiveness, as a personality trait with a genetic component, is used in tandem with a simple heuristic to determine whether or not to escalate dyadic conspecific conflicts within groups. The system is explored with individual based simulations that incorporates simple mechanisms observed across taxa, such as estimation errors in opponent fighting ability, winner and loser effects, and mortality from conflict. Previous models have resulted in unbounded inequality while we find with this model, the stratification is limited by the costs of being overly aggressive and the effects of increased relatedness due to the reproductive skew. The relationships between the time scales of hierarchy formation within groups and the evolution of the genetic trait involved in the heuristics are explored.

2 Correlates of women's rape avoidance behavior William McKibbin, University of Michigan – Flint, [email protected] Rape is a recurrent adaptive problem for females, including human women. Researchers have hypothesized that women may have evolved behavioral strategies in response to this adaptive problem. Using data provided by samples of both college students and non-college students, I examine the correlates of women’s rape avoidance behavior. Variables include measures of sociosexuality, past experience of sexual assault, and crime victimization. I also examine the relationship between women’s rape avoidance behavior and Big 5 personality factors. Discussion highlights limitations and future directions for rape avoidance research.

3 Sizing up the threat: The envisioned physical formidability of terrorists tracks their leaders' failures and successes Colin Holbrook, University of California, Los Angeles, [email protected] Daniel Fessler, University of California, Los Angeles, [email protected] Victory in intergroup conflict derives from complex factors including leadership and tactical outcomes. We hypothesize that the mind summarizes such factors into simple metaphorical representations of physical size and strength, concrete dimensions that have determined the outcome of combat throughout both phylogenetic and ontogenetic experience. Thus, in the aftermath of tactical victories (e.g., killing an enemy leader), members of defeated groups will be conceptualized as less physically formidable. Conversely, cues of effective group leadership should lead members to be envisioned as more physically formidable. Consonant with these predictions, in both an opportunistic study conducted immediately after Osama bin Laden’s death (Study 1) and a follow-up study conducted one year later (Study 2), Americans for whom the killing was salient estimated a purported al-Qaeda terrorist to be physically smaller/weaker. In Studies 3 and 4, primes of victorious terrorist leaders led to inflated estimates of terrorists’ physical attributes, and this fully mediated increases in their imagined aggression. These findings elucidate how the mind reasons about intergroup conflict.

4 Squaring off: Lanchester’s laws of combat and human combat psychology Jaimie Arona Krems, Arizona State University, [email protected] Oliver S. Curry, University of Oxford, [email protected] Robin I. M. Dunbar, Oxford University, [email protected] Dominic D. P. Johnson, University of Edinburgh, [email protected] On an L.A. backstreet, three Bloods spot a member of their rival gang, the Crips; do they attack? Lanchester’s Laws of Combat are differential equations used in military operational research–and recently applied to animal behavior–to predict the outcome, should any two sides choose to fight. Given both the consistency with which groups fought throughout our evolution and the impact such intergroup aggression likely had on cognition, Johnson (in preparation) proposed that humans have evolved a Lanchesterian battle psychology, one which helped adaptively guide combat decisions via predictions of victory. Here, we show humans do engage in nuanced Lanchesterian cognition: Outnumbered participants’ predictions of victory match those expected by Lanchester’s model of one-on-one aggression; when outnumbered, predictions mimic those of for all-against-all battles. Results provide the first evidence of this specific combat psychology and give empirical support to theories positing an adaptive history of warfare with deep evolutionary roots.

25 5 The influence of life history variables on women’s rape-avoidance behaviors Sammy Penaloza, Florida Atlantic University, [email protected] Karin Machluf, Florida Atlantic University, [email protected] William F. McKibbin, University of Michigan-Flint, [email protected] David F. Bjorklund, Florida Atlantic University, [email protected] Evolutionary theory predicts that sexual coercion and rape are likely to occur in any species in which males are more aggressive, eager to mate, and sexually assertive, and less discriminating in choosing a mate (Thornhill & Palmer, 2000). McKibbin and Shackelford (2011) state that males of many species have evolved strategies to sexually coerce and rape females. Hence, researchers have speculated that several female traits or behaviors evolved to reduce the risks of being raped. McKibbin and Shackelford (2011) hypothesized that women who responded to increased rape-related risk with more rape-avoidance behaviors may have been more reproductively successful than women who did not, and that women might possess evolved mechanisms that motivate rape-avoidance. This research examines various life-history characteristics, such as childrearing in infancy and childhood, parenting, family context, and somatic development, of women and the relationship of those with rape-avoidance behaviors. We hypothesize that women who experience harsh early childhood experiences will engage in fewer rape-avoidance behaviors than women who experience supportive childhood experiences.

6 Aggression and facial morphology: Violent criminal activity linked to larger width-to-height ratios in criminal mugshots Jessica Ayers, California State University, Fullerton, [email protected] Gorge Romero, California State University, Fullerton, [email protected] Tristan Cole-Falek, California State University, Fullerton Aaron Goetz, California State University, Fullerton, [email protected] Facial morphology provides a plethora of information necessary for individuals to make judgments about others and engage in different forms of social interactions. Recently, it has been shown that larger facial width-to-height ratios (fWHR) are linked to aggressive behaviors in males. Given this, we attempted to determine if there is a distinguishable difference in fWHR between different types of criminal offenders. It was hypothesized, using forty-six mugshots from a public database, that the fWHR of violent offenders would be larger than the fWHR of non-violent offenders. The differentiation between the offenders was operationalized by violent offenders being charged with aggravated assault (i.e., victim hospitalization due to sustained injuries) and non-violent offenders with charges of possession of a controlled substance or driving with a suspended license. Results indicated that violent offenders did have significantly higher fWHR than non-violent offenders. Discussion focuses on practical implications for fWHR in real-world scenarios.

7 The implicit rules of combat Gorge Romero, California State University, Fullerton, [email protected] Aaron Goetz, California State University, Fullerton, [email protected] Michael Pham, Oakland University, [email protected] Conspecific violence was pervasive throughout evolutionary history. This research tests the hypotheses that individuals implicitly categorize combative contexts (i.e., play fighting, status contests, warfare, and anti-exploitative violence) and use contextual information of combat to guide their expectations of behavior. In Study 1, we documented that combative contexts are readily classified from scenarios with limited but key information about the conflict in samples inside and outside the U.S. We found predictable shifts in participants’ ratings of acceptability for combative tactics across the contexts; while high-severity tactics were acceptable in warfare and anti-exploitative violence, they were restricted in a status contest and intolerable in a play fight. In Study 2, we explored the reputational consequences of violating implicit rules in comparison to tactics that self-handicap the user in a status contest. Results suggest that violation of implicit rules has reputational costs, whereas respect is garnered with self-handicapping.

8 Factors influencing the preference for indirect over direct aggression Joy Wyckoff, College of William & Mary, [email protected] Lee Kirkpatrick, College of William & Mary, [email protected] Although much theory and research has focused on the causes of “direct” aggression in response to provocation, the research literature on “indirect” aggression is sparse and fraught with conceptual and methodological problems. Our research is designed to address these deficiencies and examine the situational and individual-difference factors that lead people to sometimes employ indirect rather than direct aggression tactics. In an online study of 200 adults, we found that the degree to which participants favored an indirect over a direct aggressive response to provocation was (1) greater among women than men; (2) inversely correlated with measures of competitive self-esteem (self-perceived superiority, mate value, and dominance); but (3) uncorrelated with social-inclusion or global self-esteem. In a second study (not yet completed) of college students, we examine the commonly stated, but empirically untested, assumption that a preference for indirect over direct aggression is primarily a function of risk avoidance.

26 Attractiveness

9 He's not that into you: Facial cosmetics do not reflect men's preferences Alex Jones, Bangor University, [email protected] Robin Kramer, University of Kent, [email protected] Robert Ward, Bangor University, [email protected] Who do women impress by wearing cosmetics? Conventional accounts suggest women use cosmetics to embody desirable facial attributes, making themselves more attractive to mates. But how do men and women observers respond to cosmetic use? Photographs of models with and without cosmetics were rated by separate groups of observers on several social traits. Surprisingly, large interactions were found between the sex of the observer and cosmetics - women found models more socially desirable with cosmetics, while men showed the opposite pattern. When observers manipulated the amount of cosmetics to reflect their own preferences, women applied more cosmetics than males for Femininity, though both sexes agreed on Health. However, the actual amount of cosmetics worn by models was significantly greater than observers’ optimal amounts. We speculate that cosmetic use may serve as a mode of female intrasexual competition, and that cosmetic use challenges the universal agreement of an attractive female face.

10 Genetic analysis of facial symmetry and averageness and its implications for ‘indirect benefits’ to offspring Anthony Lee, The University of Queensland, [email protected] Dorian Mitchem, University of Colorado Boulder, [email protected] Margaret Wright, Queensland Institute for Medical Research, [email protected] Nicholas Martin, Queensland Institute for Medical Research, [email protected] Matthew Keller, University of Colorado Boulder, [email protected] Brendan Zietsch, University of Queensland, [email protected] Facial symmetry and averageness are preferred in a romantic or sexual partner. This is thought to be because these attributes indicate good genetic quality, which can indirectly benefit offspring who inherit these ‘good-genes’. This widely accepted theory underlies a large body of research, but it is based on an assumption that has not been adequately tested: if facial symmetry and averageness are preferred because of genetic benefits to offspring, a substantial proportion of the variance in these traits must be due to additive genetic variance (otherwise they could not be inherited by offspring). In order to test this assumption, we used geometric morphometrics, the statistical analysis of shape, to quantify facial symmetry and averageness in identical and nonidentical twins. Biometric modelling was used to estimate variance and covariance of facial traits into genetic and environmental components. The results have significant implications for our understanding of the evolutionary basis of facial symmetry and averageness.

11 Modulation of potential mate selection by olfactory influences on male attractiveness Noel Reynolds, University of Minnesota Duluth, [email protected] Robert Lloyd, University of Minnesota Duluth, [email protected] The contribution of the vomeronasal organ (VNO) to mammalian sexual behavior has recently come under question (Doty, 2010), and the physiological significance of this organ for human behavior has been under question for even longer. This study examined the role of the VNO/olfactory bulb (OB) as a modulating variable in the selection of a potential mate. The VNO/OB was stimulated by applying androstadienon (4, 16-androstadien-3-one), a mid-axillary compound found in the sweat of human males, to the upper lip of female subjects who were viewing slides of male faces, rating them for attractiveness. Physiological markers of arousal (blood pressure, heart rate, and salivary cortisol levels) of the female subjects were assessed. These data were compared to those taken from the same subject when only the vehicle (ethylene glycol) was applied to the upper lip. The relationship between the physiological measures and the subjective psychological ratings by the subjects was assessed.

12 Women’s faces and voices: One ornament of quality? Susanne Röder, Institute of Zoology and Anthropology, [email protected] Corinna Habenicht, Institute of Zoology and Anthropology, [email protected] Bernhard Fink, Institute of Zoology and Anthropology, [email protected] Studies showing that women’s facial attractiveness correlates positively with the attractiveness of their voices led to the conclusion that these two features may comprise one ornament of female quality, as both features are effected by the influence of sex steroids. The evidence is mainly derived from correlational studies of independent perceptions of women’s faces and voices. In the present study, male participants listened to the voices of young girls, adult women and post-menopausal women, while they were prompted to assign the face out of a pair on the screen that corresponds to the respective voice. Men’s ability to identify concordant faces and voices was significantly higher than expected by chance for young girls and adult women, but not for post-menopausal women. We suggest that this reflects an adaptive cognitive mechanism in support of the (male) preference for (female) youth and discuss our results in context if the assertion that women’s faces and voices comprise one ornament of quality.

27 13 The effect of attractiveness on time perception Joana Arantes, University of Minho and University of Canterbury, [email protected] Mark Berg, The Richard Stockton College of New Jersey, [email protected] John Wearden, University of Keele, [email protected] The goal of our study was to test a novel hypothesis derived from an evolutionary rationale – that time perception changes when an attractive opposite-sex person is unexpectedly seen. Specifically, we believe that the human timing system contains adaptations which provide flexibility in situations related to fitness, so that the duration of a briefly-viewed attractive opposite-sex photo will be judge as longer than an unattractive opposite-sex or same-sex photo. Twenty-seven female participants viewed series of stimuli of equal duration and had to reproduce the duration of the last stimulus in each series by pressing a mouse button. The first four stimuli on each trial were neutral, and the fifth stimulus was either neutral (on control trials), or a photo of an attractive or unattractive male or female (on test trials). Results show that unexpectedly viewing an attractive male affects time perception in females, and are the first demonstration that stimuli relevant to reproductive fitness, which engage the appetitive motivational system, can increase perceived duration.

14 Sex-typicality, averageness and vocal attractiveness Paul Fraccaro, McMaster University, [email protected] Jillian O’Connor, McMaster University, [email protected] Katarzyna Pisanski, McMaster University, [email protected] Cara Tigue, McMaster University, [email protected] David Feinberg, McMaster University, [email protected] Previous research suggests that averaging voices increases their attractiveness. Here we present research on averageness, attractiveness, in natural voices. We find results that contrast established results. First, harmonics-to-noise ratio is positively associated with attractiveness ratings in voices averaged via computer manipulation. We found harmonics-to- noise ratio was negatively correlated with attractiveness ratings in our sample of natural voices (r=-.443, p<0.01). Furthermore, exaggerated sex-typical features, analysed separately and using Euclidean geometry were more strongly related to attractiveness than was averageness. This result highlights an important difference between natural and averaged voices, and identifies a variable of interest for researchers studying the attractiveness of naturally-spoken voices.

15 Visual attention to and perception of undamaged and damaged versions of natural and coloured female hair Bernhard Fink, University of Göttingen, [email protected] Frauke Neuser, The Procter & Gamble Company, [email protected] Gwenelle Deloux, The Procter & Gamble Company, [email protected] Susanne Röder, University of Göttingen, [email protected] Paul J Matts, The Procter & Gamble Company, [email protected] Female hair colour is thought to influence physical attractiveness, and although there is some evidence for this assertion, research has yet not addressed the question if and how physical damaging affects the perception of female hair colour. Here we investigate whether people are visually sensitive to subtle differences in hair images of natural and coloured hair before and after physical damaging. We tracked the eye-gaze of men and women whilst they viewed pairs of images of natural and coloured hair tresses, each pair displaying the same tress before and after controlled cuticle damage. The hair images were then rated for perceived health, attractiveness and age. Undamaged versions of natural and coloured hair were perceived as significantly younger, healthier and more attractive than corresponding damaged versions. Visual attention to images of undamaged coloured hair was significantly higher than to their damaged counterparts, while in natural hair the opposite pattern was found. Future studies should investigate the impact of hair condition on perceptions of facial (and overall) female attractiveness.

16 Does hormonal birth control disrupt the assessment of mate quality through kissing? Victoria Klimaj, Knox College, [email protected] Zachary Lawrence, Knox College, [email protected] Joseph Knutson, Knox College, [email protected] Elizabeth King, Knox College, [email protected] Daniel Schaefer, Knox College, [email protected] Francis McAndrew, Knox College, [email protected] Thirteen blindfolded female college students kissed between four and seven blindfolded college males for 10 seconds. Each kiss was rated as to how attractive the woman believed the man to be and how eager she would be to kiss him again. Afterward, each woman rated 20 photographs of male faces (including the ones she had kissed) on attractiveness and eagerness to kiss. Women who were not using hormonal birth control (HBC) showed significant positive correlations between the attractiveness of a kiss and attraction to the corresponding male in a photograph. Women using HBC showed no relationship between the two sets of judgments. It may be possible that HBC disrupts female receptivity to olfactory cues relevant to the assessment of mate quality.

28 17 Mate-choice copying for same and different race faces Edward Morrison, University of Portsmouth, [email protected] Lianne Moncur, University of Portsmouth, [email protected] Mate choice copying occurs when one individual’s choice of mate is influenced by another’s, and has been observed in several species. Indirect evidence suggests the process may occur in humans too. We tested whether people’s judgements of facial attractiveness were influenced by others’ ratings of the same faces. 80 participants (41 female) rated the attractiveness of 80 faces (40 female) with deceptive attractiveness ratings that had either been raised or lowered by half a standard deviation of the genuine ratings. Half the faces were same-race, half different-race. There was a significant effect of the deceptive ratings—lowered scores resulted in lower ratings and vice versa. This effect did not vary according to the sex of face, race of face, or sex of rater. These findings are consistent with mate-choice copying, where judgments of attractiveness are not simply based on perceptual information but can be influenced by others’ opinions.

18 Closing time writ large: Perception of local pair-bond frequency and judgments of physical attractiveness Glenn Scheyd, Nova Southeastern University, [email protected] Scott Earley, Nova Southeastern University, [email protected] Perceptions of opposite sex physical attractiveness are skewed by the departure of a subset of the potential mates available at a social gathering over the course of a single evening, a perceptual shift commonly known as the closing time phenomenon. In two studies, the authors examine the broader influence of this shift as a consequence of more subtle cues to mate availability in one's local community. Study 1 required participants to rate the physical attractiveness of individuals in photographs, experimentally manipulated to be presented either immediately before or immediately after images of romantic couples. In Study 2 (in progress), the experimenter provides participants oral feedback concerning other participants' responses to the demographic questionnaire item on relationship status; in one condition the experimenter remarks on the high frequency of single participants, and in the other, their low frequency. Thereafter, the participants provide ratings of photographs as in Study 1.

19 Sex drive predicts homosexual men's and women's preferences for sexually dimorphic cues in faces Lisa Welling, Oakland University, [email protected] Kevin Singh, Pennsylvania State University, [email protected] David Puts, Pennsylvania State University, [email protected] Benedict Jones, University of Glasgow, [email protected] Robert Burriss, Stirling University, [email protected] Evidence suggests that sexual desire may strengthen men’s pre-existing (i.e., dominant) sexual behaviors, but may strengthen women’s sexual behaviors more generally. Here we show that homosexual men’s scores on the sexual desire inventory-2 (SDI-2) were positively correlated with their preferences for exaggerated sex-typical shape cues in own-sex, but not opposite-sex, faces. Contrary to the hypothesis that sexual desire strengthens women’s preferences for sex- typicality more generally, homosexual women’s SDI-2 scores were positively correlated with their preferences for exaggerated sex-typical cues in opposite-sex faces only. Together with previous research, our findings support the proposal that sexual desire strengthens existing sexual behaviors in homosexual and heterosexual men, and increases sexual responses more generally in heterosexual women, although not necessarily in homosexual women.

20 Disparities in attractiveness may trigger suspicion in romantic relationships Christian Hart, Texas Woman's University, [email protected] This study examined how disparities in perceived physical attractiveness in romantic relationships affects suspicion and the propensity to engage in infidelity. It was predicted that if a person viewed their partner as more attractive than themselves, they would be more suspicion of infidelity and less open to engaging in infidelity themselves. 238 people rated the attractiveness of their partners and themselves. They indicated how suspicious they would be and how likely they would be to cheat in a series of hypothetical scenarios and also in their actual relationships. For hypothetical relationships, increases in a partner’s relative attractiveness was associated with higher suspicion and decreased propensity for cheating. However, in actual relationships, attractiveness disparity was associated with suspicion only in women and with propensity for cheating only in men.

29 Emotion

21 The memory of disgusting episodes involving strangers compared to familiar persons Ming Peng, The Chinese University of Hong Kong, [email protected] Lei Chang, The University of Hong Kong, [email protected] Feelings of disgust differ depending on the source of the disgusting material, with that emanating from oneself and familiar others eliciting less disgust than that of strangers. Emotions relevant to survival are better remembered than those irrelevant to survival. Putting these together, we hypothesized that episodic memory of the actual content of a disgusting experience does not have the source effect because the disgusting episode is equally relevant to survival, but the actor of the disgusting episode is better remembered when it involves a familiar person rather than a stranger because there is a higher chance of meeting the former than the latter. Results from two experiments (ns = 48 and 55) showed that, whereas the content of a disgusting episode was remembered equally well independent of the actor, in matching the episodic content with the actor, familiar persons were better remembered than strangers. These results support the evolutionary explanation that memory is co-opted to better remember those emotions and episodes relevant to human survival.

22 Understanding mental constructs of emotion and language Sakshi Ghai, Indian Institute of Technology, Mumbai, [email protected] The word 'Emotion' has been microscopically studied through psychological, anthropological and biological lenses and have indubitably been one of the most researched concepts as, in all situations and reactions that constitute human life, emotions form the very niche of our mutual existence. While understanding the social aspects of cognition, one can realize that emotions are deeply interwoven with language and thereby are pivotal in inducing human actions and behaviour. The aim of this paper is threefold- first to establish the relation between mental representations of emotions and its neuropsychological connect with language on a conscious and sub-conscious level. Secondly to describe how Innate, basic and higher cognitive emotions affect the constantly changing state of an agent and peruse its assistance in determining the moral compass within all beings. Lastly, In the course of this paper, the concept of the architecture of mind is explored and how it has developed an ability to display adaptive emotional states and responses, which are in sync with the language of thought.

23 How much is too much? The role of commitment, undesirable characteristics, and disgust in relationship defection Lora Adair, Kansas State University, [email protected] Taylor Wadian, Kansas State University, [email protected] Previous work finds that feelings of disgust, triggered by stimuli that indicate infection (unpleasant odors, etc), produce distancing behaviors that serve to protect the individual from infection. Expanding on this, the current investigation seeks to determine whether characteristics commonly associated with disgust (i.e., Obesity & HPV) impact college student’s decisions to defect from a hypothetical intimate relationship. A total of 164 students (77.7% female; Mage = 18 years) read four vignettes describing hypothetical relationships. Analyses indicated that defection rates increased as both symptomology and commitment levels increased, especially with a hypothetical partner who has HPV, a potentially concealable disease. Individuals who imagined being associated with an obese partner felt more unattractive, compared to those associated with a partner who has HPV. These findings suggest that the disgust elicited from an infectious disease may have more pronounced distancing effects than disgust elicited from a disease that is not considered infectious.

24 Perceived vulnerability to disease and attitudes toward foreigners Yasuyuki Fukukawa, Waseda University, [email protected] Ryo Oda, Nagoya Institute of Technology, [email protected] Hiroko Usami, Seitoku University, [email protected] Junko Kawahito, Fukuyama University, [email protected] The purpose of this study was twofold. First, we developed a Japanese version of the perceived vulnerability to disease (PVD) scale (Duncan et al., 2009). Second, by using the scale, we addressed the question of whether PVD is associated with attitudes toward foreigners. Analysis of the data from Japanese university students replicated the two–factor structure of the original scale: one that assesses beliefs about one’s own susceptibility to infectious diseases (Perceived Infectability) and the other that assesses emotional discomfort in contexts that connote an especially high potential for pathogen transmission (Germ Aversion). Tests of reliability and validity for each subscale indicated overall promising results. We also found that negative attitudes toward foreigners were significantly associated with PVD, especially with Germ Aversion. It would appear that the association reflects evolutionary adaptive psychological mechanism against external threat.

30 25 Physiological regulation and the development of empathy during early childhood Kathryn Marsh, Florida Atlantic University, [email protected] Krystal Mize, Florida Atlantic University, [email protected] Nancy Aaron Jones, Florida Atlantic University, [email protected] The early childhood years have been identified as a crucial period for the maturation of the necessary mechanisms required for social competence later on in life. Emotions are mechanisms of survival and communication (Plutchik, 1987) and they influence how we perceive and respond to people. Positive emotions are associated with safety and security, whereas negative emotions are related to danger and stress. Moreover, empathy seems to play a central role in human interactions (Hogan, 1969). The demands of the complex social environment have enabled humans to understand and predict the behavior of others to ensure survival (Smith, 2006). Empathic behavior develops across infancy as socio-emotional capacities form from the basic affect-processing mechanisms. The current study examines the behavioral and physiological components of emotional regulation and the development of empathy in preschoolers. It also examines how the parents play a role in their child’s development of social and emotional competence.

26 Early jealousy development Krystal Mize, Florida Atlantic University, [email protected] Melannie Pineda, Florida Atlantic University, [email protected] Kathryn Marsh, Florida Atlantic University, [email protected] Nancy Jones, Florida Atlantic University, [email protected] Emotions evolved to motivate responses toward the adaptive problems faced by our ancestors. For example, jealousy activates behaviors that serve to protect valued relationships from social-rivals (Neu, 1980). Research on the role of jealousy in human ontogeny is minimal (i.e., Hart, 2010). Bjorklund and Peligrini (2002) suggest that children have evolved mechanisms to elicit parental care. According to parental investment theory, survival would be enhanced further if young children were sensitive to cues related to differential parenting attention. The current study seeks to provide evidence that the neurological underpinnings for the approach- behaviors that function to protect important social relationships are in place by the end of the first year of life. Specifically, infants will demonstrate more approach-style behavior and brain activity patterns to the loss of maternal attention to a social rival than a non-social item. Results may be indicative of a rudimentary form of jealousy.

27 Shame-prone people are more likely to punish themselves Hiroki Tanaka, Kobe University, [email protected] Asuka Komiya, University of Virginia, [email protected] Nobuhiro Mifune, Kobe University, [email protected] Ayano Yagi, Kobe University, [email protected] Yohsuke Ohtsubo, Kobe University, [email protected] Recent studies have shown that strategies of human reconciliation include self-punishment. A possible function of self- punishment is to maintain a transgressor’s reputation by signaling his/her benign intention (Watanabe & Ohtsubo, 2012). Sznycer et al. (2010) maintain that shame is an evolved psychological mechanism to limit the spread of information detrimental to one’s reputation. Accordingly, the present study investigated whether shame-prone people would be more likely to punish themselves. Participants’ shame-proneness was assessed by the Test of Self-Conscious Affect (Tangney & Dearing, 2002). Fifty participants then took part in the self-punishment experiment, in which all participants unintentionally made unfair allocation in a modified dictator game, and were given an opportunity to privately relinquish some of their reward. The amount of money that participants relinquished was the measure of self-punishment. Self-punishment was significantly correlated with shame-proneness (r = .33, p < .05) but not with guilt-proneness (r = .21, ns).

28 Love is discrimination: The adaptive function of passion in competitive interpersonal markets Junko Yamada, Hokkaido University, [email protected] Mie Kito, Hokkaido University, [email protected] Masaki Yuki, Hokkaido University, [email protected] Studies identify a number of factors that lead to success in mating. Among them is passion, defined as the “state of intense longing for union with the other.” However, the adaptive function of passion has not been fully uncovered. We propose that passion leads to discriminatory investment behaviors, by which the actor gives the greatest amount of resources to the target person, while reducing allocation to other candidates. This strategy is especially adaptive in competitive interpersonal markets such as romantic relationships; it assures the target person that the actor will not leave them in favor of other options. 82 participants were asked to rate how “passionate” and attractive various investment patterns of opposite-sex actors were. These patterns included: perfect discrimination (PD; investing all resources to only one target), moderate discrimination (MD; moderately more resources to one target versus others), and equality (EQ; same resources to all targets). As expected, PD was rated as more “passionate” than MD or EQ, regardless how much investment the target received. Moreover, PD was rated as most attractive in romantic relationships, but not in friendships.

31 29 Blood type screening: The blood-type stereotype as a tool for mate selection Kunihiro Yokota, Hiroshima Shudo University, [email protected] Human have evolved some mechanisms to avoid genetic similar partners in mate choice, especially among females (e.g., incest taboo). Several studies in the field of genetics have found that some cues, such as odor, could be used to avoid breeding with close relatives. The disgust emotion that leads to avoidance is an indicator of incompatibility, and “blood” can be powerful stimulus for revulsion. Thus, it is hypothesized that blood-type stereotypes, widely thought in Japanese popular culture to be in indicative of personality and temperament, could be used as a perceptual cue to avoid genetically incompatible partners. 161 participants rated how a potential mating partner’s blood type information would play important role in making a future connection in a scenario, and filled out the Perceived Vulnerability for Diseases scale (PVD). Results showed that females who score high on the PVD strongly believed in the advantage of blood-type information in mate selection.

30 Affiliation: Beneficial or detrimental, to your emotions and your health? Linnea Heintz, University of Wisconsin Stout, [email protected] Jennifer Byrd-Craven, Oklahoma State University, [email protected] This study attempted to better understand sex differences in stress, affiliation, and the effects it has on emotion and health. We hypothesized that females would be higher than males in emotional contagion, that females higher in emotional contagion would report a greater desire to affiliate after a stressor, and that emotional contagion would be related to reports of overall health. A multivariate analysis of variance showed males and females were significantly different on all subscales of emotional contagion; with the exception of anger. In both sexes, overall health predicted the Happiness subscale. Men, however, were also likely to report the desire to affiliate after the stressors, if they were high on Sadness and Love subscales. Demonstrating the pattern of emotional contagion and the desire to affiliate differs for men and women and focus should be placed on changes in overall health as a result of affiliation or lack thereof in response to stressors.

Mate Preferences

31 Male and female mate preferences for humor: A replication and extension William Hurwitz, University of Miami, [email protected] Liana Hone, University of Miami, [email protected] Debra Lieberman, University of Miami, [email protected] Evolutionary scientists have proposed that humor was a sexually selected trait in men that signaled a high quality mate. Indeed, Bressler et al. (2006) found that women tend to prefer men who make them laugh whereas men tend to prefer women who laugh at their jokes. Yet, it is unclear how robust this pattern is. To address this issue, we replicated the study by Bressler et al. (2006). We confirm Bressler et al.’s reported sex differences in preferences for partner’s humor production versus receptivity. Men preferred women who were receptive to their humor whereas women preferred men who produce humor. We discuss Bressler’s measures used to assess humor and suggest minor refinements. In addition we introduce a new method we used to assess how much men and women trade off humor production versus receptivity.

32 The Beauty and the Beast effect: Perceived differences in mate value Haley Dillon, Kansas State University, [email protected] Evolutionary theory provides a framework for studying mating patterns. The current study applied evolutionary theory to human mate-choice, with particular emphasis on assessments of mate value. The concept of mate settling – a lack of physical and personality-based equity within a romantic relationship – was explored through self reported online questionnaires. The surveys calculated mate value, mating intelligence, operational sex ratio and life history strategy. The current work utilized the Mate Value Inventory as well as subjective and objectivephysical attractiveness items. Perceived mate-value was associated with biological sex, mating intelligence, narcissism, life history strategy, and operational sex ratio. Females consistently reported higher values for their own mate value than for their partners’, resulting in the “beauty and the beast effect”.

33 Will musical skill attract mates? An experimental study of mate preferences as a function of musical ability Guy Madison, Umeå University, [email protected] Johan Paulin, Umeå University, [email protected] Human music has been proposed to have evolved through runaway sexual selection, as an indicator of mate value. This study experimentally tested if musical ability is employed by receivers in this capacity. Pictures of people of three attractiveness levels, along with musical recordings of three skill levels, were systematically combined to create nine skill x beauty conditions, conveyed through false associations between a face and a musical product. 27 men and 27 women rated opposing sex conditions regarding mate value and relationship interest. Results indicate that the ratings of participants of both sexes were influenced by musical ability, consistent with the evolutionary hypothesis.

32 34 Sociosexual attitudes and dyadic sexual desire independently predict women’s preferences for male vocal masculinity Jillian J.M. O'Connor, McMaster University, [email protected] Benedict C. Jones, University of Glasgow, [email protected] Paul J. Fraccaro, McMaster University, [email protected] Cara C. Tigue, McMaster University, [email protected] Katarzyna Pisanski, McMaster University, [email protected] David R. Feinberg, McMaster University, [email protected] Dyadic sexual desire is the motivation to behave sexually with a partner, whereas solitary sexual desire is the motivation for unpartnered sexual activity. Since direct reproductive success can only be increased with a sexual partner, we tested whether dyadic sexual desire was a better predictor of women’s preferences for lower-pitched voices than was solitary sexual desire. In Study 1, women’s dyadic sexual desire positively predicted their preferences for lower-pitched male voices, but their solitary sexual desire did not. In Study 2, we tested whether the relationship between voice preferences and dyadic sexual desire was due to underlying differences in sociosexuality. We found that women with more positive attitudes towards uncommitted sex had stronger vocal masculinity preferences. Also, dyadic sexual desire positively predicted women’s masculinity preferences in short-term but not long-term relationship contexts. Hence, women’s mate preferences may independently reflect individual differences in both sexual desire and sociosexual orientation, potentially with the adaptive function of maximizing the fitness benefits of women’s mate choices.

35 Waiting too long: When virginity cues abnormality instead of fidelity Amanda Gesselman, University of Florida, [email protected] Gregory Webster, University of Florida, [email protected] Research has shown that extensive sexual history—as well as recent sexual activity—leads to negative evaluation of a potential partner. Both findings suggest the existence of psychological adaptations designed to avoid sexual infidelity, cuckoldry, and sexually transmitted diseases. As such, we expected that people who were sexually inexperienced (i.e., virgins) would be preferred partners. We investigated whether sexual inexperience in adulthood was associated with positive perceptions and greater opportunities for relationships. That is, whether inexperienced people were seen as more attractive than experienced people, and thus chosen as partners. Contrary to our predictions, virginity in adulthood carried a stigma (e.g., was perceived as abnormal), especially for people in their mid- to late-twenties. Virginity was not preferred in an ideal partner, and resulted in fewer opportunities for long- and short-term relationships. Results are interpreted regarding possible adaptive signals that inexperience in adulthood may send, specifically in terms of partner quality.

36 Does hormonal birth control disrupt the assessment of mate quality through kissing? Victoria Klimaj, Knox College, Psychology, [email protected] Zachary Lawrence, Knox College, Psychology, [email protected] Joseph Knutson, Knox College, Psychology, [email protected] Elizabeth King, Knox College, Psychology, [email protected] Daniel Schaefer, Knox College, Psychology, [email protected] Francis McAndrew, Knox College, Psychology, [email protected] Thirteen blindfolded female college students kissed between four and seven blindfolded college males for 10 seconds. Each kiss was rated as to how attractive the woman believed the man to be and how eager she would be to kiss him again. Afterward, each woman rated 20 photographs of male faces (including the ones she had kissed) on attractiveness and eagerness to kiss. Women who were not using hormonal birth control (HBC) showed significant positive correlations between the attractiveness of a kiss and attraction to the corresponding male in a photograph. Women using HBC showed no relationship between the two sets of judgments. It may be possible that HBC disrupts female receptivity to olfactory cues relevant to the assessment of mate quality.

37 Mate choice throughout the stages of adolescent development Wallisen Tadashi Hattori, Federal University of Rio Grande do Norte, [email protected] Felipe Nalon Castro, Federal University of Rio Grande do Norte, [email protected] Fívia de Araújo, Federal University of Rio Grande do Norte, [email protected] Assuming adolescents are already able conceive children, selective pressure might favorite their perception of mate value and mate preferences to be as accurate as in adults, especially for oldest adolescents. However, we can also expect different importance degrees of certain traits throughout the development, which make reasonable to investigate what the components of adolescent mate value are and in what extend it differs from adult mate value. A total of 659 adolescent students (12-19 years old) took part of this study. They evaluate a 21 items Likert scale regard to self perception and short- term and long-term ideal mates. We found some differences among stages of development on self-perceived mate value and on ideal mate preferences for boys and especially for girls. The results suggest that developmental differences in relation to the mate preferences are less evident than expected.

33 38 Testing a case of intersexual selection for ear size in humans Edward Clint, UCLA, [email protected] Daniel M T Fessler, UCLA, [email protected] Claire Gordon, Natick Soldier Research, Development and Engineering Center, [email protected] Physical sexually dimorphic traits are often considered as cases of intersexual selection where they may be indicators of fertility or age. Ears grow throughout the lifespan, making them a potential target for such selection by way of indicating youth and therefore fertility potential. No previous study of sexual selection on ear size is apparent in the literature. Here, we report that female ears are significantly smaller than male ear size after correcting for age and head size. As it may be plausibly speculated that smaller auricles result in a penalty to auditory acuity, the size disparity should offer some alternate adaptive benefit. The youth cue hypothesis predicts an attractiveness preference for smaller ears in females but not males. We present a follow-up study (in progress) designed to measure preferences for ear sizes in two cultures.

39 Bad boys finish last, even for women interested in hooking up Michael Kosiak, University of Wisconsin-Eau Claire, [email protected] Angela Pirlott, University of Wisconsin-Eau Claire, [email protected] Research suggests that women prefer different men for long- versus short-term mating: “good dads” for long-term mating but “sexy cads” for short-term mating (Gangestad & Simpson, 2000). We sought to replicate this research and examine whether this preference differed depending upon women’s long- and short-term mating strategies. To test this, heterosexual college women read one of two vignettes—asking them to think of going on a date with a prototypical “good guy” or “bad boy,” and then rate their interest in going on a second date and hooking up with the guy. Women were more interested in going on a second date with the nice guy than bad boy, and were more interested in going on a date than hooking up. Interesting, however, was that there were no significant differences in willingness to hook up with the bad boy or nice guy. For women generally willing to use a short-term mating strategy, they were more willing to hook up with the nice guy than bad boy. Together, these findings provide evidence in contrast to assumptions that women prefer short- term mating with bad boys over nice guys, even for women willing to pursue a short-term mating strategy.

40 Do assortative preferences contribute to assortative mating for weight? Claire Fisher, University of Glasgow, [email protected] Corey Fincher, University of Glasgow, [email protected] Anthony Little, University of Stirling, [email protected] Lisa DeBruine, University of Glasgow, [email protected] Ben Jones, University of Glasgow, [email protected] Assortative mating for weight has implications for population health because of the combined effects of partners’ weights on fertility and/or offspring health. Although assortative preferences for cues of weight have been proposed as a factor in assortative mating for weight, there have been no direct tests of this issue. Because of this, and because of recent work suggesting that facial cues of weight convey information about others’ health that may be particularly important for mate preferences, we tested the contribution of assortative preferences for facial cues of weight to assortative mating for weight (assessed from body mass index, BMI) in a sample of romantic couples. Romantic partners’ BMIs were positively correlated and this correlation was not due to the effects of age or relationship duration. However, although men and women with heavier partners showed weaker preferences for cues of low weight, controlling for these preferences did not weaken the correlation between partners’ BMIs. Indeed, own BMI and preferences were uncorrelated. These results suggest that assortative preferences for facial cues of weight contribute little to assortative mating for weight.

41 D@ting for science: Analysing online personal ads Ulvi Piirisalu, University of Tartu, [email protected] Peeter Hõrak, University of Tartu, [email protected] In Estonia, an online dating site was built in 2007 specifically for scientific studies on sexual selection in humans. Upon registration, all users were requested to fill in a questionnaire, in which they first reported their self-perceptions on levels of various traits (offers) and then rated the importance of the same traits in expected mates (demands). In this study we analysed these two-sided questionnaires using structural equation modelling to investigate patterns underlying human mate selection. We were able to gather fully completed questionnaires for over 2000 heterosexual women and men. The traits under investigation were physical attractiveness, intelligence/interestingness, kindness, sociability, sense of humour, ambition and wealth. Specifically, we were interested in which of these traits were best predictors for the demands on expected mate’s physical attractiveness and income. The analysis was performed separately for men and women and also with respect to presence/absence of children. User’s age, age difference with expected mate, registration date, education level and place of residence were accounted for.

34 Menstrual Cycle

42 Female perception of male dance movements across the menstrual cycle Tessa Cappelle, Institute of Zoology and Anthropology, University of Göttingen, [email protected] Bernhard Fink, Institute of Zoology and Anthropology, University of Göttingen, [email protected] Bettina Weege, Institute of Zoology and Anthropology, University of Göttingen, [email protected] Studies have shown that across the menstrual cycle, women prefer masculine male features at days of high fertility (i.e., around ovulation) whereas this preference is less pronounced at days of low fertility. Previous studies showing this shift in female preferences typically concerned perception of images of male faces and bodies. The present study tested whether the reported shift in women’s preferences is also applicable to the perception of male body movement. Twenty- nine women judged ‘dance attractiveness’ of featureless humanoid characters (avatars) – devised from motion-captured movements of British men – at days of high and low-fertility in a within-subject design. Preliminary results indicate a significant effect of masculinity with masculine dancers receiving higher attractiveness ratings, but no significant menstrual cycle effect on dance perception. We conclude that (i) male masculinity is conveyed via their dance movements and (ii) women do no exhibit a preference shift for male dance movements, and discuss consequences for future research direction on the topic.

43 Intimate partner violence across the menstrual cycle Daniel Conroy-Beam, University of Texas at Austin, [email protected] David Buss, University of Texas at Austin, [email protected] The major theory on the evolution of intimate partner violence (IPV) suggests that IPV is a deterrent tactic that functions to apply costs to partner infidelity. Research on mating behavior across the menstrual cycle demonstrates that extra-pair mating is more common at ovulation relative to other points in the cycle. Given that infidelity increases precisely when conception is also most likely, it follows that anti-infidelity adaptations would have menstrual cycle-linked activation. Previous research has indeed demonstrated mate retention behavior is more common around ovulation relative to the rest of the menstrual cycle. We sought to replicate and extend this work by demonstrating that more extreme jealous behavior, i.e. IPV, is more common around ovulation. Thirty-eight naturally cycling women participated in two sessions at estimated high and low fertility. Participants reported on their partners' mate retention and IPV behaviors on both the Mate Retention Inventory and the Severity of Violence Against Women Scale. Preliminary results will be discussed.

44 Ovulation heightens perceptions of sexual threats posed by sexual orientation groups Gina Lawton, University of Wisconsin-Eau Claire, [email protected] Hillary Stone, University of Wisconsin-Eau Claire, [email protected] Angela Pirlott, University of Wisconsin-Eau Claire, [email protected] An affordance-management perspective to human cognition and behavior posits that people think about and respond to those around them in ways intended to better manage the potential opportunities and threats these others afford. The determination of situations as threats versus opportunities varies depending upon the interaction between perceiver and target variables such as sexual orientation, sex, or fundamental goals. Sexual orientation groups are perceived to pose a variety of threats and opportunities; specific to mating threats and opportunities, heterosexual women perceive bisexual men, bisexual women, and lesbians to direct unwanted sexual interest (Pirlott & Neuberg, in press). We examined whether ovulation alters women’s perceptions of the threats and opportunities afforded by sexual orientation groups, and predict, specifically, that it heightens the perceived threats posed by unwanted sexual interest targets—bisexual men, bisexual women, and lesbians. Results suggest that ovulation increases perceptions of sexual interest from bisexual men, uncomfortable sexual situations from bisexual men and women, and sexual reputation threat from bisexual and lesbian women.

45 Ovulation and disgust sensitivity towards heterosexual and gay/lesbian sexual behaviors Hillary Stone, University of Wisconsin- Eau Claire, [email protected] Gina Lawton, University of Wisconsin- Eau Claire, [email protected] Angela Pirlott, University of Wisconsin- Eau Claire, [email protected] The behavioral immune system (Schaller & Park, 2011) is a set of psychological mechanisms designed to detect indicators of pathogenic disease and elicit emotion (disgust) and behavioral responses to facilitate the avoidance of pathogens. It has been found that disgust is the anti-thesis to sexual arousal and may act as an evolutionary response to avoid biologically costly mates (Tybur, 2009). Does this disgust mechanism change in women as a function of ovulation? Given ovulating women are vulnerable to conception and pregnancy, they should be sensitive to avoiding sex with undesirable partners. Accordingly, we examined whether ovulation affects sexual disgust sensitivity to heterosexual and gay/lesbian sexual behaviors. Undergraduate women not using hormonal birth control rated their disgust to male-female (heterosexual), female-female (lesbian), and male-male (gay) sexual acts. In contrast to our hypotheses, we found that ovulation decreased disgust towards gay and lesbian sexual acts. Disgust towards heterosexual sex acts remained unchanged.

35 46 Ovulation affects lesbian and heterosexual women’s sexual attraction to gay and bisexual men Tara Young, University Of Wisconsin Eau Claire, [email protected] Angela Pirlott, University Of Wisconsin Eau Claire, [email protected] Rebecca Neel, Arizona State University, [email protected] Gabrielle Filip-Crawford, Arizona State University, [email protected] Craig Nagoshi, Arizona State University, [email protected] At ovulation, heterosexual women strategically change their mating behavior to maximize reproductive fitness, including shifts in attraction to potential (male) mating partners. But how does ovulation affect lesbian and bisexual women, whose mate attractions include same-sex targets? Ovulation could increase sexual attraction generally, regardless of target sex; suppress attraction towards undesirable mating partners; and/or increase sexual attraction specifically towards reproductively-viable targets: men. To test among these possibilities, 55 naturally cycling lesbian, bisexual, and heterosexual women rated their general sexual attraction to gay, bisexual, and heterosexual men and women. At ovulation, heterosexual and lesbian women were less attracted to gay and bisexual men (ps<.01, ƞp2=.10), whereas bisexual women's attraction to these targets was unchanged. This suggests that for lesbian and heterosexual women, ovulation may be suppressing sexual attraction towards poor long-term, yet reproductively viable, targets (i.e., non-heterosexual men).

Psychopathology

47 The Cognitive effects of depression in response to interpersonal harm: A test of the analytical rumination hypothesis Lyndsey Gott, McMaster University, [email protected] Michael E. McCullough, University of Miami, [email protected] Paul W. Andrews, McMaster University, [email protected] The problems associated with the conception of depression as a disorder have compelled researchers to investigate its evolutionary origins. The analytical rumination hypothesis (ARH) proposes that depression is an evolved response to complex problems whose function is to sustain the ruminative analysis of these problems. This study tested the ARH among university students who recently experienced an interpersonal harm (IH) by examining the relationship between IH attributes and the depressive response, and how the adopted coping strategy influenced the duration of depressed mood and status of the harmed relationship. Severe, immoral, and painful harms inflicted upon important, committed relationships were associated with the depressive response, as was distraction-free, ruminative thinking. High analysis one week after the IH interacted with rumination to predict less depression at that time, and had a negative main effect on depression five weeks later. These results support the ARH and suggest that ruminative analysis of a depression-inducing social conflict may confer protective, symptom-reducing effects over time. Theoretical and clinical implications are discussed.

48 Autistic-like and schizotypal traits in a life history perspective: Diametrical associations with impulsivity and mating styles Marco Del Giudice, University of Turin, [email protected] Amanda Klimczuk, University of Chicago, [email protected] Dan Traficonte, University of Chicago, [email protected] Dario Maestripieri, University of Chicago, [email protected] Autism and schizophrenia show diametrical patterns of associations with cognitive and social skills, brain development parameters, and physical growth trajectories. Del Giudice and colleagues (2010; Front. Psychol. 1:41) advanced a sexual selection hypothesis for the maintenance of autistic-like and schizotypal traits in the general population, and showed that these traits are diametrically associated with short- and long-term mating styles. In a life history perspective, autistic traits can be seen as part of a male-typical slow life history phenotype, whereas schizotypal traits contribute to a fast strategy in both sexes. We sought to replicate and extend these findings in a sample of US undergraduates (N=150). As hypothesized, autistic and positive schizotypal traits showed diametrical associations with mating styles. Moreover, impulsivity—a key behavioral mediator of life history strategy—showed a strong positive association with schizotypal traits and a strong negative association with autistic traits. These results support a life history/sexual selection models of autism and schizophrenia, and highlight the central role of impulsivity in their broader phenotype.

36 49 Abnormal moral judgments in psychopathy Elsa Ermer, Adelphi University, [email protected] Joshua Greene, Harvard University, [email protected] Kent Kiehl, University of New Mexico, [email protected] Psychopaths’ persistent engagement in morally unacceptable behaviors raises questions about the nature of their moral cognition. The present study investigated incarcerated psychopaths’ moral judgments across three types of scenarios: high conflict, low conflict, and impersonal (control). High conflict scenarios asked whether it was morally acceptable to take an action that would sacrifice one life to save more lives. Thus in these scenarios, “morally acceptable” responses can be interpreted as supporting a utilitarian calculus. Ninety-two adult males from a mixed-security prison completed this moral judgment. Overall, harmful actions were more likely to be judged morally acceptable in high conflict scenarios than in low conflict scenarios. Within each scenario type, however, psychopaths, compared to non-psychopaths, were more likely to judge harmful actions as morally acceptable. Psychopaths and non-psychopaths did not differ in their judgments on impersonal scenarios. These results suggest abnormal moral judgments, at least in some situations, may be important for understanding psychopaths’ immoral behavior.

50 Sick in the head? Recently ill individuals implicitly associate mental illness with disease over danger Erik M. Lund, University of Kentucky, [email protected] Saul L. Miller, University of Kentucky, [email protected] People evolved a behavioral immune system that promotes avoidance of potential sources of contagion. Previous research has shown that overgeneralization of the behavioral immune system can lead to prejudice toward the obese, elderly, and foreigners (Schaller & Park, 2011). In the current research, we examined whether the behavioral immune system is also a source of bias against the mentally ill. Indeed, biases against mental illness are pervasive and well documented (Stier & Hinshaw, 2007). However, the prevailing view is that stigma exists because the mentally ill are perceived as dangerous, violent, and incompetent (Corrigan & Cooper, 2005). In contrast to this prevailing view, our findings demonstrate that mental illness is implicitly associated more with disease than danger. Moreover, this implicit association is exacerbated among people who have been recently sick – a group of individuals who exhibit heightened behavioral immune system activation. Implications for the evolutionary origins of prejudice are discussed.

51 Darwinian psychotherapy for depression Cezar Giosan, Berkeley College / Babes-Bolyai University, [email protected] Vlad Muresan, Babes-Bolyai University, [email protected] Aurora Szentagotai, Babes-Bolyai University, [email protected] Alina Rusu, Babes-Bolyai University, [email protected] Cristina Mogoase, Babes-Bolyai University, [email protected] Drawing from insights from Evolutionary Psychopathology, a Darwinian-enhanced (Darwinian-informed) Cognitive Behavioral Therapy for Depression is proposed. Prior research has shown that Darwinian fitness is negatively associated with depression. Works of the author (e.g., Giosan, 2009) strengthen the support towards the idea that intervening on fitness dimensions can have therapeutic benefits. Standard psychotherapy for Depression (e.g., CBT) focuses on proximate causes (e.g., correcting irrational beliefs). The present therapeutic protocol proposes the addition of an evolutionary- inspired component to CBT, thus facilitating therapeutic interventions on distal (evolutionary) causes. The protocol involves using a newly created and validated Fitness Evaluation Scale, administered to patients at intake. Patients' answers to this instrument guide specific fitness-related behavioral interventions, which can work in conjunction with classical CBT.

52 Facial cues to depressive symptoms and their associated personality attributions Naomi Scott, Bangor University, [email protected] Robin Kramer, Bangor University, [email protected] Alex Jones, Bangor University, [email protected] Rob Ward, Bangor University, [email protected] Depression is a common mental health disorder, with 12% of the UK population diagnosed at any one time. We assessed whether there are cues to depressive symptoms within the static, non-expressive face, and if these may affect other socially-relevant impressions. Composite face images were created from students scoring high and low on self-report measures of depressive symptoms. A warping procedure was then used to create two versions of individual faces, one warped towards the high symptom composite, and the other towards the low. In Experiment 1, we first found observers were able to identify images representing high and low symptom occurrence at levels significantly greater than chance. Secondly, we found that observers perceived faces reflecting high, compared to low, levels of depressive symptoms to be less socially-desirable over a broad range of personality trait estimates. In Experiment 2, we replicated the key finding that the static face contains cues to levels of depression symptoms, using composites created from a new database of student photos and depression inventory scores.

37 53 A large scale test to evaluate executive function in children: Effect of age and gender Ilse Lorena Vargas, Instituto de Investigaciones Biomédicas, UNAM, [email protected] Marcos Rosetti, Instituto de Investigaciones Biomédicas, UNAM, [email protected] Robyn Elizabeth Hudson, Instituto de Investigaciones Biomédicas, UNAM, [email protected] Searching, or the set of locomotor movements made with the intention of finding objects, is a fundamental behavior common to all mobile organisms. In humans, this behavior integrates cognitive and motor skills related to executive function (EF), a broad term that encompasses functions underlying decision-making, including working memory, planning, and inhibitory control. Few attempts have been made to evaluate these functions in ethologically and ecologically valid settings. Here we present a task, reminiscent of the Easter Egg Hunt, in which 6 to 12 year-old children had to collect balls placed under orange traffic cones, arranged as a grid on a soccer field. We evaluated performance measures that reflect aspects of EF. Performance was compared with a sample of children diagnosed with ADHD. Unexpectedly, we found little difference in performance between the two groups, or with age or gender. Given the ease with which even very young children engaged in the task, we propose that this test might be useful in furthering our understanding of the development of executive function by presenting more complex stimulus arrays.

Religion and Morality

54 When justice isn’t blind: Closeness, morality, and punishment Kelly Asao, University of Texas at Austin, [email protected] People value certain individuals over others. Friendship, kinship, and group membership are relationships characterized by emotional closeness and mutual interests. The current study investigated whether people’s moral judgments are systematically influenced by their relationship to the victims of crimes. Both type of relationship and closeness were used to predict judgments of moral wrongness and deserved punishment across three types of crime: theft, physical harm, and rape. I found evidence for a strong positive relationship between closeness and both measures of moral judgment for each crime type. That is, as closeness between the evaluator and the victim increased, judgments of moral wrongness and deserved punishment became harsher. These findings have important implications for our intuitions of morality. Specifically, future research should investigate the ways in which relationships between victims, moral evaluators, and perpetrators influence people’s morality and impartiality.

55 Religiosity and information seeking across domains Brock Brothers, Oakland University, [email protected] Jennifer Vonk, Oakland University, [email protected] We explored whether individuals with varying degrees of religious faith would report using different information seeking strategies in various domains. Participants completed measures assessing their religiosity and decision-making strategies in seven domains (social, financial, political, education, employment, medical, and religious). We hypothesized that those with higher degrees of religiosity would be less likely to seek empirical sources when making decisions across these domains. Repeated measures ANOVAs indicated that empirical information-seeking strategies were not used consistently across domains (F 5.83, 2629.54 = 32.43, p = .001) and that religious affiliations significantly interacted with domain to predict strategy use (F 5.83, 2629.54 = 7.391; p < .001). However, contrary to our expectations, those who were more fundamentally religious were less likely to seek further information only with regard to religious aspects of their lives (β = -.228, t = -3.669, p < .001) but not necessarily as a domain-general trait.

56 Religious cognition increases endorsements of sexual (but not cooperative) morality: A first look Liana S. E. Hone, University of Miami, [email protected] Evan C. Carter, University of Miami, [email protected] Eric J. Pedersen, University of Miami, [email protected] Michael E. McCullough, University of Miami, [email protected] Reproductive Religiosity Theory (RRT) posits that sexually restricted strategists use avowals of religious beliefs to enforce their reproductive interests (i.e., coerce others toward adopting restricted sociosexual strategies). Based on RRT, individuals who are told that their moral views will be made public (as compared to kept private) to others in their mating pool should endorse higher levels of morality if they have first been asked to consider religion. Furthermore, when controlling for cooperative morality (CM), religious priming should increase endorsements of sexual morality (SM) but when controlling for SM, priming should not increase endorsements of CM. We tested this using two 2 (public/private condition) x 2 (religious/no prime) ANCOVAs (N = 238) with CM as the covariate and SM as the DV (and vice versa). We found no main effect for publicity condition, but we found a main effect for religious prime: Controlling for CM, participants primed with religion endorsed significantly higher levels of SM, but not vice versa. Thus endorsements of sexual (but not cooperative) morality are apparently influenced by religious cognition.

38 57 Does it matter who pulls the switch? Perceptions of intentions in the Trolley Dilemma Jesse Marczyk, New Mexico State University, [email protected] Humans face the adaptive problem of predicting the likely behavior of those they interact with. One means through which people try to predict the behavior of others would be through perceptions of their intentions; what goals others seek to achieve through their behavior. Unfortunately for perceivers, intentions are not readily observable in the same way that physical traits like eye color are; rather intentions need to be inferred from other cues. One of those cues might be perceptions of who benefits and suffers from an act. When reacting to a Trolley Dilemma, holding the act (pulling a switch) and the outcome (5 live, 1 die) constant, the payoff for the person who pulls the switch matters when it comes to moral judgments.

58 Sex differences in the relationship between religiosity and reproductive behavior Melvin Philip, State University of New York at New Paltz, [email protected] David Widman, Juniata College, [email protected] Rebecca Newmark, State University of New York at New Paltz, [email protected] Glenn Geher, State University of New York at New Paltz, [email protected] Briana Tauber, State University of New York at New Paltz, [email protected] Morgan Gleason, State University of New York at New Paltz, [email protected] The Reproductive Religiosity Model claims religion serves to support “slow” sexual and reproductive strategies. In women, high religiosity correlates with low numbers of desired mates and rates of sexual behaviors. Results for men are mixed. The current study replicates these findings and investigates religiosity’s effect on desired number of children. Participants answered questions about their sexual history, desired number of sex-specific offspring, sex-specific sexual partners, and the extent to which their religious beliefs influence their sexual strategies. They also complete the Religious Commitment Inventory-10. Results showed that both religiosity indices correlated negatively with the desired number of opposite-sex partners for women, but not for men. Men reported desiring more male offspring than women. More interestingly, both religiosity indices were positively correlated with the number of desired male offspring only in men. Findings suggest that religion serves high fertility strategies for men while serving low-promiscuity strategies for women.

Signaling

59 Facial redness as a social signal: Sensitivity threshold of colour changes in facial skin and colour patches Kok Wei Tan, University of Nottingham Malaysia Campus, [email protected] Ian Stephen, University of Nottingham Malaysia Campus, [email protected] Human facial skin colour reflects individuals’ underlying health (Stephen et al, 2011), and enhanced facial skin yellowness, redness and lightness are perceived as healthier by Caucasian and South African participants (Stephen et al, 2009, 2011). Individual are able to discriminate minor changes in skin blood coloration in faces (Re et al., 2011), possibly due to selection for ability to detect social signals (Changizi et al, 2006). Here we examine Malaysian Chinese’s detection thresholds to CIELab lightness, redness and yellowness on human skin (n=51) and colour patches (n=48) in two different studies. Changes in facial redness were found to be more easily discriminated than changes in yellowness or lightness. We, however, failed to detect the same high sensitivity towards redness when using colour patches as stimulus, suggesting special significance for red as a social signal of human faces.

60 Cognitive responsiveness of adults to basic infant expressions Chinmay Aradhye, Oakland University, [email protected] Jennifer Vonk, Oakland University, [email protected] Infants are born with the ability to express distress and joy with distinct facial expressions (Darwin, 1972; Ekman, 2006). Adults show consistent voluntary and involuntary sensitivity to crying and smiling infant facial expressions (Hilderbrandt 1983; Power, Hildebrandt & Fitzgerald, 1982). The details of this evolved infant-adult interdependent relationship are currently unknown (Luo, Li & Lee, 2011). One possible function for these kinds of communication signals is intraspecific manipulation (Dawkins & Krebs, 1978) in which members of the same species indulge in the manipulation of another members' behavior using specific signals. To study the cognitive responsiveness of adults to basic infant expressions, we aim to measure untrained adults' viewing duration, perceived cuteness, and desire to adopt in 15 different infants as a function of different emotional expression conditions (smiling, crying, neutral). We will also determine whether individual adult characteristics, such as perspective-taking and empathy are correlated with differential responsiveness to the infants’ emotional states.

39 61 Dominance and deference: The effect of social status on creative display in a competitive mating context Daniel Gambacorta, New Mexico State University, [email protected] Timothy Ketelaar, New Mexico State University, [email protected] Dominance is a form of status derived from the ability to control resources via threat of physical force. We propose that one way that humans defer to more dominant individuals is by inhibiting creative displays in competitive mating contexts. This deference functions to prevent physical harm being brought on by the more dominant individual. Forty-nine male participants were led to believe that they were competing with another male for the chance to go on a lunch date with an attractive female. Participants were shown a shirtless picture of their competitor. The picture depicted either a dominant (strong) male or a subordinate (scrawny) male. Videotapes of participants being interviewed by the female with the male competitor watching were then rated on several dimensions by a team of coders. Results revealed that participants competing against a dominant male produced fewer and lower quality creative displays than participants competing against a subordinate male.

62 The (al)lure of exploitability: Signaling sexual exploitability to attract a mate Cari Goetz, The University of Texas at Austin, [email protected] Judith Easton, Texas State University at San Marcos, [email protected] Cindy Meston, The University of Texas at Austin, [email protected] David Buss, The University of Texas at Austin, [email protected] The present set of studies tested the hypothesis that women who are more inclined toward short-term mating will be more likely to signal sexual exploitability to attract a mate compared to women less inclined to short-term mate. In Studies 1 and 2, women rated the likelihood that they, or another woman, would use mate attraction tactics that signal sexual exploitability to sexually attract a mate. Study 3 provided a behavioral measure of signaling exploitability. Fifty-seven women created hypothetical video dating profiles that were later coded for exploitability-signaling. Results from all studies supported the hypothesis. Short-term mating women endorsed that women would be more likely to use mate attraction tactics that involve signaling exploitability and were more likely to signal to exploitability in their dating profiles. Results demonstrate that women inclined toward casual sex may uniquely capitalize on the relationship between exploitability and sexual attractiveness to achieve their mating goals.

63 Relationship value predicts costly apology-making: A test of the valuable relationships hypothesis of human reconciliation Yohsuke Ohtsubo, Kobe University, [email protected] Ayano Yagi, Kobe University, [email protected] The valuable relationships hypothesis posits that people have an inclination to reconcile with their valuable-relationship partners. Focusing on costly apology-making, the present study tested whether relationship value would enhance participants’ willingness to make a costly apology. Based on an evolutionary model of direct reciprocity, relationship value was divided into relationship longevity (how long participants expected that the relationship with the particular friend would last) and instrumentality (how useful the victim was in enabling participants to achieve their important goals). After imagining that they committed an interpersonal transgression against one of their real friends, participants (N = 529) rated relationship value of that friend and their willingness to incur certain costs in order to apologize to the victim. The result supported the hypothesis: Both longevity and instrumentality independently facilitated participants’ willingness to make a costly apology. In addition, the result indicated that expectation of the victim’s forgiveness down-regulated costly apology.

64 Exploring how social relationships influence gestural communication in a captive population of bonobos Elizabeth Orr, University of St. Andrews, [email protected] Richard Byrne, University of St. Andrews, [email protected] Bonobos use an extensive repertoire of gestures to communicate their goals and intentions to conspecifics. In this study I consider how social relationships between signalers and recipients influence use of gestures across dyads. Video recordings of gestures within social interactions among 17 bonobos were taken at the Milwaukee County Zoo, Wisconsin, over the course of 14 months in 2011-12. For each bonobo I consider the choice of gestures, what they used them for, and the strength of social relationships across dyads. Social relationships influence gestural communication, especially when it comes to signaling a demand versus an offer of social interaction. For example, asking the recipient to “groom me” through the use of gestures is almost exclusively done by the higher-ranking individual within a dyad whereas the lower-ranking bonobo will only offer grooming (“groom you”) and never demand grooming in return. These findings indicate that gestural communication may provide bonobos with a tool for managing multiple relationships.

40 Cognition

65 “The dog bites the man” or “the man bites the dog”? Evolution of relation discriminating system of language through iterated learning Ayumi M. Osawa, University of Tokyo, [email protected] Kazuo Okanoya, University of Tokyo, [email protected]‑tokyo.ac.jp Various scenarios have been proposed to account for the evolution of the uniquely human ability to use syntactically structured language. Recent research often employs the iterated learning model (Kirby & Hurford, 2002) in which ‘generations’ of experimental participants produce object-label mappings after observing the mappings produced by the previous generation. Through the iteration of this learning-production process, initially random mappings often acquire a systematic function that assigns consistent labels to objects. Our study examined whether this framework could also account for the evolution of a system that uniquely labels objects composed of an identical set of sub-elements. The results revealed it stands under certain circumstances. This finding could add an implication of how syntax of human language, especially the function of discriminating relations of sub-elements has evolved.

66 Domain specificity in prepared learning for foods and artifacts Christopher Peterson, UCLA, [email protected] Clark Barrett, UCLA, [email protected] Willem Frankenhuis, Radboud University Nijmegen, [email protected] Information about environmental dangers is expected to be acquired faster than less fitness relevant information by children. Previous work has shown that cross-culturally, children exhibit such prepared learning effects for danger within the domain of animals. Shuar children of Amazonian Ecuador as well as children in Los Angeles were shown to remember propositional information regarding whether animals were dangerous or not to a greater degree than other propositional information about those animals, including their diets and their names. Other domains for prepared learning for danger may exist, and this study explores possible effects for dangerous artifacts and foods, two classes of objects relevant to the fitness of ancestral populations. Here we show that children in the U.S. and in the Shuar display prepared learning for whether foods are safe or dangerous to eat, and show prepared learning in the U.S. but not in the Shuar, for information about safe and dangerous artifacts, suggesting that unique properties of artifacts and cultural attitudes about them may be sufficient to mediate the effect.

67 Visual attention may affect accuracy of cheater detection Toko Kiyonari, Aoyama Gakuin University, [email protected] Yukako Inoue, University of Tokyo, [email protected] Shigehito Tanida, Taisho Uniersity, [email protected] Hideyuki Takahashi, Osaka University, [email protected] Toshikazu Hasegawa, University of Tokyo, [email protected] Although there is some evidence suggesting that people can discriminate defectors from cooperators from their faces, there is no study to investigate which region of target’s face people more likely to pay attention to during their judgments. To investigate the possible differential allocation of attention between accurate judges and inaccurate judges, we conducted a cheater detection judgment experiment along with recording judges’ eye-movement by the eye-tracker (Tobii 2150). We used 30 seconds video clips as stimuli which were taken from Kiyonari’s (2010) cheater detection experiment. In Kiyonari’s study, the targets (i.e., first-players of the sequential prisoner’s dilemma game) were informed that the video would be shown to their potential partners (i.e., second-players) before their decisions. In our study, 56 participants (i.e., judges) were asked to estimate whether the target cooperated or defected in the PD game. The results of our experiment suggest that judges whose accuracy of judgment was high tended to look at eye region more than those who were low in accuracy.

68 Ecological evaluation of executive function Marcos Rosetti, Instituto de Investigaciones Biomédicas, [email protected] Elena Ulloa, Hospital Psiquiátrico Infantil Juan N. Navarro, [email protected] Robyn Hudson, Instituto de Investigaciones Biomédicas, [email protected] Searching, or full body displacements to locate and collect objects, requires that motor, sensory and cognitive skills come together in a coordinated way in order to produce a successful outcome. In humans, the ability to search in an organized manner minimizing visits to the same place while scanning the environment efficiently can be considered a proxy for the working of executive functions, a theoretical construct which postulates a set of cognitive processes operating at the top of a regulatory cascade. We investigated searching using a task in which participants had to collect golf balls hidden under traffic cones distributed as a grid on a soccer field. Primary school students and hospital patients with a diagnosis of attention deficit and hyperactivity disorder (ADHD) participated in the study. A strikingly similar subset of both samples showed consistently poor performance, suggesting poor coordination of executive functions. We suggest that this simple method could provide an ecologically valid test appropriate even for very young children, and that performance descriptors could provide objective criteria for diagnosis and potentially differentiating clinical subjects.

41 69 Modularity in evolutionary psychology Malte Dahlgrun, Humboldt University Berlin, Department of Philosophy, [email protected] One of the most prominent philosophical challenges to evolutionary psychology’s modularist view of the mind is due to Richard Samuels. Emphasizing that the modules posited by evolutionary psychologists are innate, domain-specific (IDS) computational mechanisms, Samuels argues that modularism is “unwarranted and unmotivated”, since the general arguments offered in its favour fail to give us reason to prefer it to an alleged alternative: positing bodies of truth- valuable IDS representations processed by domain-general computational mechanisms. I argue that Samuels’ criticism fails and ignores several basic facts. Most importantly: (1) Evolutionary psychologists explicitly posit IDS mechanisms with rich IDS representational structures inextricably tied into them. (2) Motivational adaptations are only conceivable as mechanisms rather than bodies of information. To the extent that motivation pervades the mind, as evolutionary psychologists believe it does, their talk of IDS mechanisms is justified. (3) Samuels’ persistent claims of evidential parity for domain-generally processed IDS representations versus IDS mechanisms are never supported and highly implausible.

70 The case for modularity: An analysis of four theoretical arguments for domain specificity Michael Dale, North Carolina State University, Philosophy, [email protected] In one of their papers, Leda Cosmides and John Tooby put forward four theoretical arguments for why it is likely that humans evolved domain specific brain structures as opposed to a more general system. The first argument asserts that specialized mechanisms would make more evolutionary sense because they would do a better job at addressing the vast array of survival issues. Their second argument maintains that because fitness success and failure is different from one problem to the next, it makes more sense to have a module for each problem. Their third and fourth arguments center around the idea that there is not only a lot of information that we need to know in order to survive but there also seems to be a lot of information that we already do know. For Cosmides and Tooby, these two facts indicate that we do not have domain general brain systems. However, my analysis shows that Cosmides and Tooby repeatedly pigeonhole domain generality, and that there are, in fact, domain general brain systems that could deal with all these issues. Because of this, domain specificity should not be accepted as the brain system to have most likely evolved.

71 What is the relationship between number and density? An introductory investigation in young human infants Claudia Uller, [email protected] Animals and human infants discriminate numerosities in visual sets. Experiments on visual numerical judgments generally contrast sets in which number varies (e.g., the discrimination between 2 and 3). What is less investigated, however, is set density, or rather, the inter-stimulus distance between the entities being enumerated in a set. In this study, we investigated the role of set density in visual sets by 10-month-old infants. In Experiment 1, infants were offered a choice between two sets each containing 4 items of the exact same size varying in the distance in between the items (ratio 1:4). Infants selected the set in which the items are close together (higher density). Experiment 2 addressed the possibility that this choice was driven by a strategy to 'select all in one go' by reducing the size and distance of items. Ten-month-olds selected the sets with higher density (less inter-stimulus distance) in both experiments. These results, although bearing replication because of their originality, seem consistent with principles in Optimal Foraging in animals. They provide evidence that a comparable rudimentary capacity for density assessment (of food items) exists in infants, and may work in concert with their numerical representations.

72 Quantifying natural selection with PfN Kim Lutz, University of Idaho, [email protected] Susan Klebba, University of Idaho, [email protected] Russell Jackson, University of Idaho, [email protected] Environmental navigation and perception are primary selective forces across species. Researchers assume that organisms universally Prefer the Nearest of otherwise equidistant goals (PfN). This is important because PfN quantifies the strength of selection acting on many behaviors. For example, the distances that ungulates travel to reach mineral deposits, rodents travel to find a low-predated nesting site, or a human travels in order to avoid a falling risk all quantify selection strength for that behavior. Despite this evolutionary importance, PfN was uninvestigated prior to the current study. Human participants in two experiments completed a retrieval task that tested PfN. Surprisingly, data indicate that PfN is not universal. Data also indicate that the strongest cue for PfN is not the distance to the nearest goal, but to the farthest. These methods provide the first means for determining broad navigation motivations across species and in a way that quantifies selection in natural environments. Within humans, these data hold implications for behaviors as diverse as food selection, habitation preference, and, in modern contexts, physician selection and driving habits.

42 73 From Pinker to Panksepp: Emotion, music and the evolution of language Shiva Jade Motlagh, Université Paris 8/Ecole Normale Supérieure de Paris, [email protected] Mary Maxwell, [email protected] Jaak Panksepp (2008) argues that the motivation for the 'language instinct' may be found in our emotional and musical urges sheltered by the subcortex. In his article 'The Power of the Word May Reside in the Power of Affect', he draws attention to the tight coupling of musical competence and social-cognitive abilities in the human species. We investigate this, using William’s syndrome and autism as examples.

74 The influence of disease concerns on group membership categorization Anastasia Makhanova, University of Kentucky, [email protected] Saul Miller, University of Kentucky, [email protected] Humans easily classify others into “ingroup” and “outgroup.” We suggest that group membership classifications are not static but that fundamental motives like survival and reproduction influence the focal characteristics along which distinctions are made. Thus, when motivated to avoid disease, individuals may use heuristic cues to disease (e.g. old age, different race) to determine ingroup/outgroup membership. In the current studies, we hypothesized that disease concerns would influence ingroup/outgroup categorization. In both studies, participants classified 20 pictures of men (young/old, White/Black) as ingroup or outgroup. In Study 1, White participants with chronic disease concerns classified elderly, Black men as the outgroup more often than other men. In Study 2, White participants primed with disease (vs. control) concerns classified elderly, Black men as the outgroup more often. The findings support our hypothesis that chronic and situational disease concerns facilitate the reliance on heuristic cues to disease in group membership categorization.

Cooperation

75 Comparing the behavior of chimpanzees and children in a Stag Hunt Game Shona Duguid, Max Planck Institute for Evolutionary Anthropology, [email protected] Emily Wyman, Max Planck Institute for Evolutionary Anthropology, [email protected] Anke Schirmer, Max Planck Institute for Evolutionary Anthropology, [email protected] Michael Tomasello, Max Planck Institute for Evolutionary Anthropology, [email protected] The study of the evolution of human cooperation has recently focused on how individuals coordinate with one another. One coordination problem, the ‘Stag Hunt Game’, forces players to make a critical decision: either secure a low payoff individually, or try to secure a high payoff by cooperating with a partner. But cooperation entails a risk: a solo attempt to retrieve the high value prize results in no reward. In a comparative study, we presented both chimpanzee and child dyads with a Stag Hunt Game, and examined their tendencies towards cooperation, as well as strategies employed to overcome the associated risk. We found both species were likely to risk cooperating in conditions in which they could easily monitor their partners. However, when visual access to the partner at the moment of decision was blocked, chimpanzee cooperation was hindered to some extent. Children, by contrast, communicated with partners before making a decision regardless of condition, apparently reducing the perceived risk overall. These results point to divergence in the evolved strategies associated with coordination, highlighting the importance of communication in solving coordination problems.

76 Influence of age on competitiveness in children and adolescents Monique Leitão, Federal Institute of Education, Science and Technology of Rio Grande do Nor, [email protected] Danyelle Costa, Federal Institute of Education, Science and Technology of Rio Grande do Nor, [email protected] Renara Rocha, Federal Institute of Education, Science and Technology of Rio Grande do Nor, [email protected] Maria Emília Yamamoto, Federal University of Rio Grande do Norte, [email protected] Infant traits and cues of vulnerability or inability could affect empathy and willingness to help, probably related to the need to care for helpless infants. Human tendency to cooperation is rooted in mechanisms that originally evolved to care for offspring. The aim of this study was to investigate the influence of age on the cooperative behavior of individuals who have different levels of knowledge about a game. Children and adolescents were tested in dyads composed by child-child (4-5 years old versus 8-9 years old) and child-adolescent (4-5 years old versus 14-16 years old) that played rounds of tic- tac-toe. The data indicate that both children and adolescents express high competitiveness, but in some conditions cooperative behaviors were observed. The subjects’ experience of living and caring for young infants seem to influence cooperative behavior. The results suggest that differences on interaction could be explained by developmental differences in relation to sexual maturity and the tendency toward parental care.

43 77 Uncooperative risk takers Adam Sparks, University of Guelph, [email protected] Sandeep Mishra, University of Regina, [email protected] Pat Barclay, University of Guelph, [email protected] Risky behaviors (e.g. violence, gambling, dangerous driving, promiscuous sex, crime) tend to co-occur in individuals, and are reliably associated with variance preference in laboratory tasks. Further, these behaviors seem to be similarly influenced by environmental conditions like income inequality. Such findings suggest the existence of a general variance preference mechanism influencing behavior in various domains. Noting that many real world risky behaviors involve social defection - the pursuit of selfish gain at the expense of others – we predicted that defection in a laboratory economic game would be correlated with non-social risk taking. Indeed, Prisoner’s Dilemma Game defection was significantly associated with higher levels of risk-taking behavior in experimental tasks. The link between risk taking and cooperation/conflict deserves further study.

78 Solution to the collective action paradox within a behavioural synchrony framework Tamas David-Barrett, University of Oxford, [email protected] Robin Dunbar, University of Oxford, [email protected] Humans possess prefer to help members of their group irrespective of genetic relatedness, a rare feature among animals. This poses a theoretical conundrum that has not been solved by either the evolution of society literature of kin-selection, or economics models of exchange-based cooperation, or group-selectionist theories of selection on a higher organisational level. Here we suggest a new model of the emergence of cooperative human groups. We use a behavioural synchrony model to show that it is possible for sociality to evolve as individual trait if the payoff function is affected by synchronisation efficiency. We also show that the emergence of cooperated among unrelated individuals is most likely to take place when the means of the interaction is ‘language-like’, leading to a gradual emergence of a trait that would be too costly at the beginning of the process.

79 Intergroup conflict may inhibit coalescing of large human groups and decrease returns from cooperation Lauri Sääksvuori, University of Hamburg, [email protected] Recent theoretical advances and quasi-experimental evidence from modern conflict areas suggest that intergroup conflict and ostracism play a pivotal role in the evolution of cooperation. However, relatively little is known about the role of intergroup conflict and ostracism on group formation and human migration. Here, we show that intergroup conflict may inhibit coalescing of large human groups and decrease individual net returns from cooperative behaviors. Moreover, we find that competitive pressure between groups decreases the likelihood of being punished through ostracism. Our results suggest the importance of stable group boundaries on the evolution of human cooperation through intergroup conflict and point to the dangers of implementing group contests to foster human cooperation.

80 How differences in relatedness affect children’s altruistic behavior across age Karin Machluf, Florida Atlantic University, [email protected] David F. Bjorklund, Florida Atlantic University, [email protected] The ability to exhibit altruistic behaviors is considered as one feature that distinguishes humans from other species (Haviland et al. 2004). A recent surge of studies regarding children’s altruistic behavior has emerged. Benenson et al. (2007) used a Dictator Game to test 4-, 6-, and 9-year old’s altruistic behavior towards a classmate and found that even the youngest children behaved altruistically some of the time. Moore (2009) tested differences in children’s altruistic behavior using group membership and found that giving depended on group membership. These findings may have been skewed by the presence of the researcher (Fehr, Bernhard, & Rockenbach, 2008). This study seeks to replicate the findings of Moore (2009) while using a modified Dictator’s Game and an anonymous design in order to measure 3, 4, 5, and 6- year-old children’s altruistic giving without the influence of a researcher. We hypothesize that in-group members will receive more than out-group members, but not as much as a genetic relative. Children’s theory of mind and understanding of social norms will also be measured, since both correlate highly with altruistic behavior.

81 Cooperative human action: How much is “human?” Ashley Micklos, UCLA, [email protected] Co-operative action refers to the joint construction of shared goals by interacting individuals performing operations on diverse materials. The organization and co-operation of human action allows people to coordinate activity in ways that might not be present in other animals. People engage in joint action by bringing together meaningful materials (e.g. language, cultural artifacts) simultaneously, and performing operations on a prior, public substrate (e.g. action, talk). Naturalistic data best demonstrate these features of human co-operative action. The current study examined in detail the joint construction of action for counting discrete objects in a grandmother-grandson dyad during ‘reading time.’ In addition, a comparative analysis with cetaceans and primates’ interactional behavior is conducted to investigate the uniqueness of the organization of human action as examined here. Distinctions between human and nonhuman animal co- operative behavior may shed light on the evolutionary origins of the complexity of human action, and how such a system helps solve species-specific adaptive problems. Implications for pedagogy, culture, and language are also discussed.

44 82 How do assortative grouping and information about others’ cooperativeness affect cooperation? Jaakko Junikka, University of Jyväskylä, [email protected] Franjo Weissing, University of Groningen, weissing [email protected] Lucas Molleman, University of Groningen, [email protected] Piet van den Berg, University of Groningen, [email protected] Mikael Puurtinen, University of Jyväskylä, [email protected] Both theory and empirical data indicate that assortative grouping increases cooperation among conditional cooperators, i.e. individuals who are willing to cooperate if others are not deceiving. The decision whether to cooperate or not depends on individual’s personal preferences, and on expectations about the behavior of other subjects. Information about the past behavior of others can have a strong effect on these expectations and on cooperativeness. We use computer-implemented Public Goods social dilemma Game to study how information of other players’ previous cooperativeness modifies the effect of assortative grouping on cooperation. We manipulate the way groups are formed (assorted according to cooperativeness vs. random) and the availability of information about past cooperativeness of others (information available vs. no information available).

83 Third party compensation: The insurance of social life Erik Thulin, University of Pennsylvania, [email protected] Cristina Bicchieri, University of Pennsylvania, [email protected] Recent experiments show that third parties, in addition to punishing perpetrators, compensate victims at a cost to themselves. In this poster, we test the hypothesis that third party compensation evolved as a response to first parties recruiting these third parties in order to expand their pool of possible cooperative partners beyond their social- reputational network. Studies 1 and 2 test the expanding social circle hypothesis by measuring whether individuals, when acting as first parties, possess and utilize the complex cognitive capacities, in particular 3rd order beliefs, necessary for the theory. Exploring beyond our own theory, studies 3 and 4 test the effect and scope of compensation, which we hope will aid future theory development. Study 3 measures the impact of compensation on possible victims by measuring willingness to invest in a trust game when one is protected or unprotected by compensation. Study 4 measures the scope of compensation behavior by looking at whether third parties’ willingness to compensate varies depending on whether the victim lost their resources due to a norm violation of another participant, an investment decision, or purely random chance.

84 Social and ecological influences on adolescent prosociality Abram van Leeuwen, University College London, [email protected] Ruth Mace, University College London, [email protected] Cooperative or prosocial behavior is one of the central topics in the evolutionary social sciences. Several evolutionary perspectives exist for explaining between-individual differences. Cultural evolutionists emphasize the social transmission of cultural norms and maintain that cultural processes independent of the immediate ecological context play a crucial role in the spread of prosocial norms. Another view, derived from life history theory, holds that in the type of harsh and unpredictable environments that should give rise to accelerated life histories with relatively short time horizons, a shift away from prosociality towards exploitation may be adaptive. The current study is an empirical examination of determinants of between-individual variation in adolescent prosociality, using data from a British birth cohort study. Our models include several predictors of particular interest to evolutionary social scientists: 1) school-peer prosociality; 2) harshness and unpredictability of the childhood environment; and 3) levels of direct parental care. A key objective is to evaluate the relative influence of peers and parents, and social influence versus ecological factors.

85 A general factor of sociality in groups: The coordination of cooperation and the mechanisms that maintain it Daniel O’Brien, Harvard University, [email protected] Prosociality (e.g., cooperation) varies across groups, and can determine the capacity to achieve collective goals (i.e., collective efficacy). This study posits that the behaviors that underlie collective efficacy evolved through multilevel selection to support group-level function. This thesis would require that collective efficacy be dependent on a suite of group-level traits that include cooperation as well as those mechanisms that maintain it across time. These would comprise a general factor of sociality with three components: 1) cohesion between members, 2) the enforcement of prosocial norms, and 3) the transmission of prosocial norms across generations. The current study tests this concept in Boston, MA, comparing social patterns across neighborhoods (defined as Census block groups, N = 542). Confirmatory factor analysis found that seven survey scales reflecting the three proposed components shared a single governing factor: 1) density of social networks, social cohesion, reciprocity; 2) social control, reporting of crime, attitudes toward domestic abuse; 3) intergenerational closure. Further analysis of the factor satisfied three important tests of the thesis: it mediated relationships between demographic variables and all survey scales; it was distinct from perceived and objective measures of disorder and crime; and it independently predicted outcomes relevant to resident fitness.

45 86 Examining the relationship between code of honor and anger at unfairness in the third-party punishment game Daniel Forster, University of Miami, [email protected] Eric Pedersen, University of Miami, [email protected] Michael McCullough, University of Miami, [email protected] People vary in their tendencies to become angry when treated unfairly and when witnessing others’ receipt of unfair treatment. Recent research has suggested that environmental cues indicating that life will be harsh and short predict people’s propensity to defect when unprovoked, and to retaliate when provoked, in an iterated prisoner’s dilemma game. The observed relationship was mediated by participants’ endorsement of a “code of honor.” The present research further explores these effects by examining the same set of relationships using data from 680 participants (from three separate studies) who played either a third-party (or second-party) punishment game. We used structural equation modeling to evaluate whether harsh environmental cues were associated with anger toward (and punishment of) unfair dictators, and to assess whether code of honor endorsement mediated these relationships.

87 Social influences on 18-month-olds' prosocial behavior Emily K. Newton, Stevenson University, [email protected] Miranda Goodman-Wilson, Eckerd College Ross A. Thompson, University of California Davis A vast body of research suggests that social influence should play an important role in individual differences in young children’s social behavior, yet many claim that the early ontogeny of prosocial behavior is unaffected by specific social environments (Warneken & Tomasello, 2006). In the present study, we tested the influences of maternal sensitivity and maternal mind-mindedness (MMM; mothers’ conceptualization of their children as psychological agents) on 18-month-olds’ prosocial profiles. Using prosocial scores derived from eight behavioral tasks, Latent Class Analysis was used to test models with 1-4 latent classes. The best fitting model had three latent classes, categorized as high, moderate, and low in prosociality and containing approximately 21%, 44%, and 35% of the participants, respectively. Infants with mothers high in maternal sensitivity were close to five times more likely to be in the high prosocial group than the low prosocial group and 3.53 times more likely to be in the high prosocial group than the moderately prosocial group. Infants with mothers high in MMM were over 850 times more likely to be in the highly prosocial group than the moderately prosocial group. Contrary to the assumption that early experiences have minimal influence on prosociality, these findings suggest that the quality of the caregiver-child relationship is an important ecological force in the development of children’s prosocial behavior. These findings have implications for the competing nativist and cultural evolutionary views of ontogeny and suggest that social learning plays a vital role in the development of prosocial dispositions.

88 The effects of ownership on allocations in the Dictator Game John Christner, Washington University, [email protected] Pascal Boyer, Washington University, [email protected] People’s implicit assumptions about ownership might influence their decisions in the Dictator Game (DG), leading to generosity. Participants read a story about a ritual structurally analogous to the DG. Participants were told that in some instances the ritual was interrupted before completion and were asked who owned the endowment and how it should be allocated after such interruptions. Results showed that participants assumed the endowment primarily belonged to the experimenter throughout the DG, unless the dictator worked to earn it and that allocations were strongly predicted by judgments of ownership. These ownership intuitions might account for allocation decisions in actual DGs.

Kinship and Parental Investment

89 Did sexual fluidity in women evolve to promote alloparenting? Barry Kuhle, University of Scranton, Department of Psychology, [email protected] Sarah Radtke, Ryerson University, Department of Psychology, [email protected] We propose the alloparenting hypothesis, which posits that sexual fluidity in women is a contingent adaptation that increased ancestral women’s ability to form pair bonds with female alloparents who helped them rear children to reproductive age. A fluid sexuality would have helped ancestral women solve the adaptive problems of a dearth of paternal resources due to rape and to their mates’ death, desertion, or divestment of resources by promoting the acquisition of allomothering investment from women. Under this view, most heterosexual women are born with the capacity to form romantic bonds with both sexes. Sexual fluidity is a conditional reproductive strategy with pursuit of men as the default strategy and same-sex sexual responsiveness triggered when inadequate paternal investment occurs or when women with alloparenting capabilities are encountered. Discussion focuses on (a) evidence for alloparenting and sexual fluidity in humans and other primates; (b) alternative explanations for sexual fluidity in women; and (c) and circumstances predicted to promote same-sex sexual behavior in women.

46 90 Gender differences in sibling detection: A facial EMG study of incest aversion Delphine De Smet, Ghent University, [email protected] Linda Vanspeybroeck, Ghent University, [email protected] Jan Verplaetse, Ghent University, [email protected] Previous research pinpointed two association-based cues for sibling detection: co-residence duration and maternal perinatal association. Earlier we established that EMG-measured activity in the m. levator labii in young adult females showed shared intimacy during early childhood to be an additional cue. In the current study we aimed to test for gender differences in incest aversion, as predicted by parental investment theory. Additionally, we tested the hypothesis of an early imprinting period for sibling detection, in which case shared intimacy should be relevant in early, but not late childhood. Through a guided computer task with still images, participants (N= 170, 66 males) imagined performing sexual activities with their oldest opposite-sex sibling. Simultaneously, facial expressions of disgust were measured by EMG activity in the m. levator labii region. Females’ results point to the existence of an efficiency-driven sibling detection model based on maternal perinatal association and both early and late childhood shared intimacy. Unexpectedly, males’ EMG responses were as high as females’, and decreased when more co-residency duration and shared intimacy were reported.

91 Influence of viewing immature faces on adult aggression and fine-motor skills Patrick Sellers II, Florida Atlantic University, [email protected] Karin Machluf, Florida Atlantic University, [email protected] Alyson Myers, Florida Atlantic University, [email protected] The evocation of caretaking behavior from adults for the aid of a child is a critical task for survival given the dependent nature of infancy. An obvious immature physical characteristic with adaptive function is the general facial neoteny of infants which convey immaturity not just in humans, but across species (Lorenz, 1943). Viewing neotenous pictures increases behavioral carefulness (Sherman, Haidt, & Coan, 2009) in addition to eliciting higher ratings of cuteness and higher levels of self-reported motivation for caretaking behavior (Glocker, Langleben, Ruparel, Loughead, Gur, and Sachser, 2009). These influences of neoteny on adult behavior and motivations are likely important precursors to explicit caretaking behavior. A complimentary mechanism for garnering caretaking behavior from adults may be to also decrease aggression. Therefore, we propose that viewing infant faces is likely to decrease adult aggression more so than viewing the faces of adults or neutral stimuli. Aggression will be measured pre and post stimulus viewing, in addition to an assessment of change in fine-motor skills performance, a measure of behavioral carefulness.

92 Aunts and Uncles invest more in full than half siblings’ children: Results from the Generational Transmissions in Finland surveys Antti O. Tanskanen, University of Helsinki, [email protected] Mirkka Danielsbacka, University of Helsinki, [email protected] Kin selection theory predicts that genetic relatedness will affect kin investment. However, there is lack of studies that analyze whether aunts and uncles invest differentially in their full than half siblings’ children. We use two nationally representative surveys from the Generational Transmissions in Finland project. Surveys are collected from the older generation (born in 1945–1950, n=2,278) and from the younger generation (born in 1964–1990, n=1,753) separately. We found that both generations reported more contacts with full than with half siblings’ children. The results show that genetic relatedness may play an important role in aunts’ and uncles’ relationships with their nieces and nephews.

Sex and Mating

93 An analysis of the differences in the bestselling pornography movies geared toward men and the top selling pornography movies made for women with an emphasis on investigating female sexual fluidity and male mate attraction. Sarah Radtke, Ryerson University, [email protected] In this study, I will analyze the 20 bestselling pornography movies of all time that are geared toward a male audience and those made for a female audience. A major component that will be studied is female same sex behavior in films geared toward men and movies made for women. Other aspects that will be explored are storylines, dialogue, and the ambience of the movies indicating differences in the mating psychology of women and men. Heterosexual males generally find the idea of two females engaging in sexual activity arousing. One area that this study will focus on is mate attraction and female same sex behavior. If females are tuned into males being sexually attracted to female same sex behavior, they may exploit the behavior to attract a mate perhaps for short term or long term mating. By evaluating pornography geared towards men and women and examining female same sex behavior in each category, the study hopes to demonstrate that mate attraction is one impetus for the evolution of female sexual fluidity.

47 94 Sex and marriage strategies: An investigation into the punishment of non-monogamous mating strategies David Widman, Juniata College, [email protected] Melvin Philip, State University of New York at New Paltz, [email protected] Rebecca Newmark, State University of New York at New Paltz, [email protected] Glenn Geher, State University of New York at New Paltz, [email protected] Briana Tauber, State University of New York at New Paltz, [email protected] Morgan Gleason, State University of New York at New Paltz, [email protected] Due to the altricial nature of offspring, Homo sapiens have evolved monogamy as a long-term mating strategy. However, non-monogamous reproductive behaviors are not uncommon. These tactics can be perceived as a form of reproductive cheating. When given the opportunity to punish these “cheaters,” there may be consistent variation in regards to the terms of the punishments meted out. This study examined whether the presence of children, the gender of the “cheater” and the gender of the respondent would affect the punishment and severity of the transgression for reproductively relevant cheating behaviors, specifically polygamy. We found that both the gender of the respondent and the presence of children significantly affected the punishment and estimates of the severity of the transgression. Men meted out less punishment than women and the presence of children from polygamous marriages generated more punishment and greater transgression. This pattern of punishment is consistent with both the evolved nature of mating strategies between the sexes and the hypothesis that marriage is a reproductive contract.

95 The joint effects of testosterone and sexual double standards on sexual opportunism Katherine Valentine, Singapore Management University, [email protected] Norman Li, Singapore Management University, [email protected] Testosterone and sexual opportunism (willingness to engage sexually with attractive unfamiliar others) was measured in 56 men and 59 women in Singapore. Men were most sexually opportunistic when told that sexual double standards (SDS) exist, while women were most sexually opportunistic when told that SDS have been eradicated. For men, testosterone and SDS independently predicted sexual opportunism such that an increase in either was associated with increased sexual opportunism. For women, testosterone and SDS interacted in their effect on sexual opportunism: testosterone had no effect when women read that SDS persist, but in the control condition (no mention of SDS) and when told that SDS have been eradicated, increased testosterone was associated with increased sexual opportunism. Sexual opportunism was highest when women were told that SDS no longer exist and testosterone was high. Because women’s testosterone levels are highest around ovulation, ovulation combined with permissive cultural norms might increase women’s sexual opportunism. Results support a biocultural perspective of human behavior.

96 Men’s interest in their partner’s copulatory orgasm: A matter of public relations Anna Hummel, Oakland University, [email protected] Viviana Weekes- Shackelford, Oakland University, [email protected] Todd Shackelford, Oakland University, [email protected] Female copulatory orgasm may function to preferentially retain the sperm of a favored male. The risk of sperm competition, in turn, predicts men’s interest in their long-term partner’s copulatory orgasm. We are interested in examining men’s interest in their partner’s copulatory orgasm in the context of uncommitted, non-exclusive, heterosexual relationships. We hypothesize that men’s interest in their partner’s copulatory orgasm in this context will be correlated with the number of reproductive-aged female contacts shared by the partners. The number of shared reproductive-aged female contacts serves as a cue for the potential for gossip. We expect men to be more interested in their uncommitted partner’s copulatory orgasm when the potential for gossip is higher because this may aid men in securing future mating opportunities.

97 Men’s proprietary views of their romantic partners Justin Lynn, California State University, Fullerton, [email protected] Aaron Goetz, California State University, Fullerton, [email protected] Kim Steele, California State University, Fullerton, [email protected] Previous research suggests that men maintain proprietary views of their romantic partners and attempt to control a large portion of their social lives. However, this literature hasn't differentiated between the specific aspects of their romantic partners’ lives that men seek to control. For many years it has been implied that men attempt to exert general control over their partners, yet recent research guided by evolutionary theory suggests that this control may be more domain-specific. The purpose of the following studies was to test the hypothesis that men will afford their partners most freedoms, except for those related to their sexuality. Results show that men reported increased tolerance for their partners’ participation in activities not related to sexuality, and this tolerance decreased as the relation of the activities to a potential EPC strengthened. This suggests that evolutionary theory can provide a useful framework for understanding men’s proprietary views of their partners.

48 98 Hard economic times and mating motives: Recession cues differentially affect women’s eating strategies Marjorie Prokosch, Texas Christian University, [email protected] Danielle Delpriore, Texas Christian University, [email protected] Christopher Rodeheffer, Texas Christian University, [email protected] Sarah Hill, Texas Christian University, [email protected] Cues to resource scarcity increase mating goal immediacy, consistent with a faster life history strategy. For women, whose body fat plays a key role in attracting mates and regulating fertility, these cues are also expected to affect eating habits. Because a thin body type is preferred in our culture, dire economic news should lead single women to decrease calorie consumption to increase their ability to attract a mate. Partnered women are expected to increase calorie consumption to ensure sufficient body fat for reproduction. First, single women showed slower reaction times to unhealthy food words on a lexical decision task after exposure to scarcity cues. Next, female participants were given the opportunity to eat junk food. Single women ate fewer calories after exposure to scarcity, whereas partnered women ate more. This extends previous work that shows the recession promotes mate attraction goals in single women and mating goals in partnered women.

99 Female orgasm frequency and reproductive status Alyse Ehrke, Oakland University, [email protected] Viviana Weekes-Shackelford, Oakland University, [email protected] Yael Sela, Oakland University, [email protected] Todd Shackelford, Oakland University, [email protected] Human female copulatory orgasm may be an adaptation to preferentially retain the sperm of a favored man, thereby increasing the likelihood of current conception. If female copulatory orgasm is an adaptation to bias paternity, we hypothesize that reproductive-aged women will report a greater frequency of copulatory orgasm than will post- reproductive-aged women. Previous research indicates that women may fake copulatory orgasm as part of a broader mate retention strategy. Women are more likely to fake copulatory orgasm when the risk of partner infidelity is higher, for example. As a woman ages, her reproductive value decreases and, therefore, her partner may be increasingly susceptible to infidelity. Therefore, we also hypothesize that post-reproductive women will report greater frequency of faked copulatory orgasm than will reproductive women. We will collect self-report data from women aged 18-80 years to test these hypotheses.

100 Female copulatory orgasm and male partner attractiveness Yael Sela, Oakland University, [email protected] Viviana A. Weekes-Shackelford, Oakland University, [email protected] Todd Shackelford, Oakland University, [email protected] Female copulatory orgasm may function to retain sperm from males with “good genes”, one indicator of which is attractiveness. Women mated to more (vs. less) attractive men are more likely to report experiencing an orgasm while copulating with their partner. The current research replicates and extends these findings. Self-reports from 550 women in a committed, heterosexual relationship indicate that women mated to men they rate as more (vs. less) attractive are more likely to report orgasm at last copulation. This significant relationship remained after controlling for other variables, including relationship satisfaction (also positively related to female orgasm). Novel to this study, we constructed a composite measure of attractiveness that included women’s perceptions of other women’s assessments of their partner’s attractiveness. This composite measure of men’s attractiveness positively predicts female copulatory orgasm, even after controlling for other variables. The current study highlights the importance of female orgasm in post-copulatory sexual selection.

101 Who gossips with you will gossip of you: Perceptions of reputation-based gossip from the perspective of the mate target and mate rival Katelin Sutton, Macquarie University, [email protected] Megan Oaten, Macquarie University, [email protected] This research examines the role of gossip in derogating romantic competitors. Previous research has indicated that both males and females are willing to share gossip information in order to achieve a desired mating outcome. I present two studies, using qualitative and quantitative measures, that extends such research by providing the first test of reputation- based gossip from the perspective of the mate target (Study 1) and mate rival (Study 2). Findings suggest that hearing derogatory gossip information about one’s current mate partner negatively affects both feelings towards the partner and the relationship in general. Additionally, while hearing derogatory gossip about oneself was found to negatively influence perceptions of the gossiper, individuals were generally unwilling to engage in retaliatory behaviour. These findings suggest that reputation-based gossip is an ideal derogation strategy for an individual to employ in mate competition.

49 102 Attractive and slim as a female strategic link: BMI, mate value, intrasexual competition, and punitive reactions to infidelity Ana Maria Fernandez, Universidad de Santiago de Chile, [email protected] Michele Dufey, Universidad Diego Portales, [email protected] José Antonio Muñoz-Reyes, Universidad de Playa Ancha, [email protected] Body Mass Index (BMI) is an important anthropometric component of female attractiveness, and in this sex, attractiveness is the main component of reproductive success. There are some studies that have linked BMI and women´s mate value, as well as physical attractiveness to mate value, and intrasexual competition; and there are a few studies of the association of mate value with punitive reactions to infidelity. In three independent samples of Chilean college females we analyzed the correlation of BMI with mate value (N=234), BMI with Intrasexual competition (N=147), and BMI with punitive reactions to infidelity (N=131). Our results showed an inverse relationship of BMI with all the variables for young women, which in turn were significant in some cases and stronger in other cases. We discuss the impact of young age combined with low BMI as an important advantage for women mate value, intrasexual selection, and mate retention.

103 Four functions for four relationships: Consensus definitions of four different relationships Peter Jonason, University of Western Sydney, [email protected] Recent years have seen the range of relationships under investigation to have expanded beyond one-night stands and monogamous pairbonds but standard operational definitions have yet to be fashioned. In this study (N = 192; 124 women, 68 men), consensus definitions of one-night stands, booty-call relationships, friends-with-benefits, and serious romantic relationships were fashioned. Participants provided a Likert and forced-choice assessment of how each relationship was characterized by the functions of sexual gratification, trial run, placeholder, and socioemotional support. Serious romantic relationships were primarily used to gain socioemotional support. Friends-with-benefits relationships were motivated by seeking a placeholder until something better comes up and as a trial run. Booty-call relationships and one-night stands were motivated primarily by a desire for sexual gratification. Men ascribed a greater range of reasons to engage in sexual relationships than women did and the more short-term the relationship was in nature, the greater the emergence of sex differences in ascribed functions.

104 Partner pregnancy affects human sperm parameter and interest in partner’s copulatory orgasm John Arvanitis, Oakland University, [email protected] Sperm competition occurs when the sperm from two or more males concurrently occupy a female’s reproductive tract and compete to fertilize the ovum. Human males attend to social and physiological cues to sperm competition. When the risk of sperm competition is higher, men ejaculate more sperm in their next copulation, for example. Female orgasm may function to preferentially retain sperm from men with “good” genes. During gestation, women often report a decrease in sexual desire, frequency of sexual intercourse, and orgasm. The proposed study will test the hypotheses that (1) sperm parameters are affected by partner pregnancy, a clear indication of the absence of current sperm competition, and that (2) men with pregnant partner’s will be less interested in their partner’s copulatory orgasm.

105 When competition turns costly: Exploring mating strategies among female friends Michele Alesia, Nova Southeastern University, [email protected] Valerie Starratt, Nova Southeastern University, [email protected] Cooperation is a valued quality in female friendships, however previous research describes intrasexual competition as a sexual strategy women use to compete with rival women for access to desirable mates. Although competitive behavior may be a beneficial mating strategy, it may pose great costs to women whose rivals are also their friends. Therefore, we hypothesized that in a mating context women would behave differently among rival-friends than rival-strangers. Hypotheses were also developed to investigate variables that would differentially predict mating behaviors among women in the two conditions. Results suggest that women in general are more likely to engage in non-competitive than competitive mate attraction behaviors. When women do compete, however, it is more likely to occur with rival-strangers than rival- friends. Women’s mate attraction behaviors also seem to be influenced by women’s personality, self-esteem, physical attractiveness, and general life-strategy.

106 The relationship between sexual fantasy and strategies of human mating: An exploratory study Christopher Holland, Knox College, [email protected] Heather Hoffmann, Knox College, [email protected] The relationship between sexual fantasy and mating strategies is a greatly understudied topic in evolutionary psychology. 197 participants (76 males, 121 females; mean age = 22.96; range 18-69; SD = 7.72) responded to an online survey designed to gather information about sexual fantasies, relationship status, and sociosexual orientation. Data analysis revealed that relationship context, sex, and sociosexual orientation were significant correlates of the frequency of various fantasy themes. Interest in short vs. long term mating was more important in determining the content of sexual fantasy than the sex of the fantasizer.

50 107 How do women fake an orgasm? Mark McCoy, Oakland University, [email protected] Todd Shackelford, Oakland University, [email protected] Lisa Welling, Oakland University, [email protected] Vivianna Weekes-Shackelford, Oakland University, [email protected] Human female orgasm may function to selectively retain the sperm of particular men (Baker and Bellis, 1995) and may aid in women’s retention of a long-term partner (Kaighobadi, Shackelford, & Weekes-Shackelford, 2012). As part of a broader mating strategy, women can fake an orgasm with their long-term partner to maintain or increase his investment in the relationship while selectively retaining the sperm of another man by achieving genuine orgasm with him. We used an act nomination procedure to construct an inventory of cues that women report using in an effort to fake an orgasm during sex with a partner. We present the categories of cues nominated by women and discuss future research designed to identify which cues are most and least successful in convincing a man that his partner has achieved orgasm when she, in fact, has not.

Personality and Individual Differences

108 Formidability and future discounting: Evidence that stronger men have a greater preference for immediate rewards Adar Eisenbruch, UCSB, [email protected] Rachel Grillot, UCSB, [email protected] James Roney, UCSB, [email protected] Organisms face behavioral and physiological tradeoffs between present competition and mating effort vs. investing in improving their prospects for future mating effort and competition. Physical strength may have been a recurrent cue of men’s ability to win mating opportunities and other resources, such that stronger relative to weaker men may be more calibrated toward immediate competition and the pursuit of present vs. future rewards. The present study found that young men with greater physical strength exhibited greater future discounting – that is, they expressed a larger preference for immediate (as opposed to delayed) rewards. Higher future discounting was also positively associated with lifetime number of sex partners, and with the self-reported likelihood of getting into a fight in the next 12 months. These patterns suggest that individual differences in men’s rates of future discounting may be explained in part by their levels of immediate investment in mate competition. Implications are discussed with respect to life history theory and facultative calibration of behavioral strategies.

109 Similarities and differences between heterosexual and homosexual couples based on MARQ data Kraig S. Shattuck, Wayne State University, [email protected] Lisa M. Dillon, Lawrence Technological University, [email protected] Glenn E. Weisfeld, Wayne State University, [email protected] With the recent social and political interest in same-sex marriage a number of claims about same-sex couples have arisen, but few of these claims are based upon theory or research. For the last twenty years the 230-item Marriage and Relationship Questionnaire (MARQ) has been used to assess couples in many different cultures, looking at a multitude of relationship related questions. Until recently the MARQ has mainly been given to heterosexual couples. In an effort to rectify this, the MARQ was used to asses 169 gay and lesbian couples. Using evolutionary theory we developed a series of hypothesized differences and similarities that homosexual couples would exhibit vis-à-vis heterosexual couples (e.g. overall relationship satisfaction would be similar, but division of labor within the couple would be different). While there are a number of limitations of this study, we hope that the results that we have obtained will help illuminate the actual behavioral differences and similarities exhibited by heterosexual and homosexual couples.

110 Does self-monitoring predict interest in gossip? Amelia Goranson, Knox College, [email protected] Francis McAndrew, Knox College, [email protected] Ninety undergraduate students (29M, 61F) completed questionnaires measuring self-monitoring and interest in three types of gossip: strategy-learning gossip, celebrity gossip, and personal gossip. Females were significantly more interested in personal gossip than were males, and interest in different types of gossip was strongly intercorrelated. However, self-monitoring was at best a weak predictor of interest in gossip. The results are discussed from the perspective of interest in gossip as an evolved psychological mechanism for enhancing success in social competition.

51 111 Career influencing factors: A comparison between women and men Katharina Olsacher, University of Vienna, [email protected] Martin Fieder, University of Vienna, [email protected] Men, of high socioeconomic status (measured as occupational prestige, education and income), tend to have more children compared to men of lower socioeconomic status., In women on the contrary, socioeconomic usually is negatively associated with the number of children a women has.. To get a better understanding of factors influencing social status we used the Wisconsin Longitudinal Study from 1975 and 1993. We investigated how sex, number of children, number of siblings, education, parental education, religiosity, attractiveness and the personality (big 5) and other factors, influencing social status (measured by being on a supervisory position and income). We found out, that sex of the participants, personality and education have a major effect on social status: Receptive personalities tend to have better chances to achieve high occupational prestige and income. Number of children seems to have a negative influence on the career of young women, an effect that decreases with age. However, factors influencing the career of women and men seem to be comparable, but only men really benefit “biologically” by social status.

112 The relationship between androstadienone preference and disgust sensitivity in detectors and non-detectors Lorenzo Stafford, University of Portsmouth, [email protected] Lucienne Larrabure, University of Portsmouth, [email protected] Elisha Dutch, University of Portsmouth, [email protected] Research has shown that female preference for masculine faces was positively associated with pathogen disgust sensitivity. Since masculinity can be an index of genetic quality, but is also associated with short-term relationships, this appeared to show evidence of a ‘trade off’ between a preference for short-term relationships. In the current research we extend this theory to examine if another potential marker of male genetic quality (androstadienone) is also related to disgust sensitivity. In the study here, young females (n=60) completed a threshold detection and preference test to androstadienone followed by the Three Domains of Disgust questionnaire. Results revealed that for those females able to detect androstadienone, pathogen disgust was positively associated with disgust odor ratings, which was not seen in those not able to detect this odor. These findings suggest that the relationship between putative markers of male genetic quality and disgust sensitivity may be more complex than previously thought.

113 Gender differences in the perception of attractive faces of the opposite sex Pu Xiaoping, The Chinese University of Hong Kong, [email protected] Tse Chi-shing, The Chinese University of Hong Kong, [email protected] Ancestral women’s reproductive success (RS) is related to procurement of good genes, good provisions, and good fathers, whereas ancestral men’s RS especially from short-term mating concerns mainly assurance of fertility. In this study we examined gender differences in the perception of facial attractiveness which was operationalized as the extent of sexual dimorphism (i.e., masculinity vs. femininity). Because a feminine face represents fertility which is almost the sole concern for male RS and a masculine face represents good gene which is one of the concerns for female RS, we hypothesized faster visual search to female facial femininity by men than male facial masculinity by women. The hypothesis was supported based on 60 Chinese participants participating in a visual search task. Whereas both women and men showed faster reaction time in searching feminine female faces than non-feminine female faces, reaction time among women did not differ in searching masculine compared to non-masculine male faces. These findings support the evolutionary understanding of gender differences stemming from different ancestral survival and reproductive challenges faced by men and women.

114 The AVPR1A gene and human personality traits: Implications for the evolution of individual differences and pairbonding Shimon Saphire-Bernstein, UCLA, [email protected] Laura R. Saslow, University of California, San Francisco, [email protected] Sarina R. Saturn, Oregon State University, [email protected] Dacher Keltner, University of California, Berkeley, [email protected] Preliminary research suggests a role for the AVPR1A gene in human pairbonding, but the mechanism by which this gene might influence human pairbonding is not yet known. Here, we report the results of a study investigating the association of the AVPR1A RS3 microsatellite with a number of personality measures, including a measure of the Big Five. Carriers of the 334 allele of RS3, previously associated with reduced relationship quality, had higher levels of extraversion and its assertiveness facet (p < .001 for both). In men, this allele was also associated with the frequency of voluntary altruistic behaviors (e.g. charitable giving, donating blood), whereas no such effect was observed in women (p = .001 for the gene by sex interaction). Discussion will focus on the potential for these findings to account for the previously observed effect on the quality of pairbond relationships. Implications of the sex differentiated findings will also be discussed, as well as a possible role for balancing selection in maintaining variation at this locus. We conclude by considering the utility of candidate gene association research for furthering our understanding of the evolution of human behavior.

52 115 Biological sensitivity and life history: How sensory processing sensitivity and early childhood environments moderate financial risk taking in adulthood Ethan Young, University of Minnesota, [email protected] Chiraag Mittal, University of Minnesota, [email protected] Stephanie Cantú, University of Minnesota, [email protected] Vladas Griskevicius, University of Minnesota, [email protected] Jeffry Simpson, University of Minnesota, [email protected] Recent evolutionary-developmental models suggest that individuals vary in their biological sensitivity to context (Ellis et al., 2011). Accordingly, this theorizing suggests biologically sensitive individuals are affected more than insensitive individuals by positive and negative childhood circumstances. These circumstances are utilized as cues to calibrate development and influence behavior to match the local ecology. Similarly, life history theory predicts that risky behavior in adulthood is contingent on childhood experiences because, in particular environments, riskiness yields different fitness payoffs (Griskevicius et al., 2011). Low or high rates of childhood harshness and unpredictability lead individuals to adopt a slow (less risk taking) or fast (more risk taking) life history strategy. The current research embeds biological sensitivity within a life history framework; findings indicate that higher levels of biological sensitivity moderate the relationship between experimentally induced mortality threats and childhood socioeconomic status. Specifically, sensitivity both increases and attenuates risky financial decision-making in adulthood depending on rearing contexts.

116 Marital status, divorce and underlying factors in a large Finnish sample I. Määttänen, University of Helsinki M. Jokela, University of Helsinki Background: Marital status has been shown to be associated with personality and sex hormone levels. However, large, population-based samples concerning both sexes and both personality- and testosterone variables are rare if not non- existent. Understanding the relationships between neuroendocrinology, personality and behavioral outcomes is crucial for understanding the causal mechanisms of human pair-bonding and sexual behavior. Sample: A large Finnish population-based sample collected from the longitudinal Young Finns Study-research was used. There were 686-973 men and 1208-1254 women in this sample, depending on the study variable. Aims: In this study we studied the following questions: a) is marital status associated with personality and b) with testosterone, and whether or not c) divorce is associated with personality and with d) testosterone. Results and Discussion: Novelty seeking had a positive association with divorce, especially among women. Testosterone, on the other hand, had a positive association with not being married or cohabiting with a partner, but only among men. It has previously been established that among men, testosterone is positively associated with novelty seeking. In this study, this relationship was much stronger among non-married men, whereas in women there was no association between novelty seeking and testosterone. It is possible that a two-way relationship exists among personality and marital status among men – both higher novelty seeking and testosterone predict higher probability of obtaining and losing a partner. In men, the ability to adjust the levels of testosterone and novelty seeking to current relationship status may have an important adaptive function. The apparent lack of association between testosterone and novelty seeking in women deserves further attention.

117 Mutually attracted or repulsed? An actor–partner interdependence model of the Dark Triad in couples Gregory Webster, University of Florida, [email protected] Carrie Smith, University of Mississippi, [email protected] Benjamin Hadden, University of Houston, [email protected] Peter Jonason, University of Western Sydney, [email protected] Amanda Gesselman, University of Florida, [email protected] Laura Crysel, University of Florida, [email protected] The Dark Triad traits—narcissism, Machiavellianism, and psychopathy—form a set of adaptive personality strategies selected to exploit others. Although the Dark Triad traits have been studied in individuals, little is known about their roles in dating relationships. Thus, 45 heterosexual dating undergraduate couples (N = 90) self-reported measures of the Dark Triad and relationship commitment and satisfaction. Using actor–partner interdependence models showed (a) men’s narcissism was positively related to women’s commitment and satisfaction, (b) men’s Machiavellianism was positively related to men’s commitment and women’s commitment and satisfaction, (c) men’s psychopathy was negatively related to men’s satisfaction and women’s commitment and satisfaction, (d) women’s narcissism was positively related to men’s satisfaction and women’s commitment, and (e) women’s psychopathy was negatively related to men’s and women’s commitment. Within couples, assortative mating was negative for narcissism but positive for Machiavellianism and psychopathy. We discuss possible implications for couples’ adaptive relationship strategies.

53 118 State female median full-time and salaried income and in-law avoidance motivation: Novel predictors of women's surname retention at marriage Melanie MacEacheron, University of Western Ontario, [email protected] Hyphenating or keeping their premarital surnames for U.S. destination brides marrying in Hawai'i in 2010 was highly and significantly correlated with median full-time and salaried women's income by bride's state of residence ("Median Women's Income": r=.78, p<.000) and by the analogous statistic for men by bride's state of residence (r=.64, p<.000). Median Women's Income, only, remained significant under OLS regression of both predictors. The interaction of state Gini and Median Women's Income, in an OLS regression with these plus state Gini alone, as predictors, was also found to be positively predictive: none of several other potential predictors suggested by previous research or related to Gini or to Women's Median Income were significant predictors alongside Women's Median Income. The older the bride, from any jurisdiction, marrying in Hawai'i in 2010, the more likely she was to hyphenate or keep her premarital surname (χ2(1) for linear trend=1754.65, p<.000). Theory is advanced that those women who must pander to their future in-laws for economic reasons via marital surname change do so more frequently. Theory is also advanced that in-laws constituted a selection pressure on daughters-in-law over evolutionary time. A survey of 132 female, never-married, undergraduate psychology students in a large North American city was conducted: attitudes toward taking their husband's surname at marriage were collected. Hypotheses: approval of marital surname change would vary with subjects' views on the importance of high resource potential in a candidate husband, and resource transfer from and involvement with, in-laws. All indicators of approval for and actual marital surname change previously cited in the literature feasible to collect were collected. Those that were correlated with approval for women's marital surname retention were entered into the same OLS regression, along with the hypothesized predictors, as predictors of attitude to women's marital surname change. Decreased approval of marital surname change was significantly predicted only by desire for in-laws to not be involved with the woman, her husband, and their offspring.

119 Evolutionary psychology theory on motivational differences in consumer decision making Marie-Anne Simons, UMCG/RUG, [email protected] Jan Guus Waldorp, UMCG/RUG, [email protected] Harry Van de Wiel, UMCG/RUG, [email protected] Evolutionary psychology is fundamental for understanding the motivational underpinnings of consumer behaviour. Nevertheless, a framework for researching individual differences in consumer motivation is still missing. The aim of our study is to find the possible foundations for such a framework. We establish what existing evolutionary psychological findings can contribute and what new research is needed. We find the Five Factor personality traits reflect adaptive social strategies. Being mental fitness indicators they are inherently evaluative in decision-making processes of consumer motivation mechanisms. They do not, however, explain the social strategies nor the criteria for valuation of signals of mental fitness indicators. Hypothesizing that social strategies are possible adaptive solutions for problems of information processing in ever larger evolving social systems, we found explanations for three social strategies. We propose the Handicap Principle for providing criteria for signals of mental fitness indicators that correlate with these social strategies. We conclude showing how our findings can provide a robust framework for individual differences in consumer motivation.

120 Misunderstanding in cross-sex relationship initiation Miguel Pita, Universidad Autónoma de Madrid, [email protected] Enrique Turiegano, Universidad Autónoma de Madrid, [email protected] We conducted a study (n=205) among college students (from Spain) in order to get a better knowledge of cross-sex relationship in the precise moment of initiation. We observed that for men sexual attraction is the most important reason to initiate a cross-sex relationship, while female participants showed a clear tendency consider establishing a new friendship as the main motivation. Although individuals from both sexes considered that the opposite sex had no other intentions than friendship. We analyzed several personal and social characteristics of participants that might modulate their opinion about cross-sex relationship initiation, but gender turned out to be the most important personal feature explaining the results.

121 Gender differences in Christmas gift-giving and the evolution of female friendships Mark Dyble, University College London, [email protected] Robin Dunbar, University of Oxford, [email protected] As a measure of altruistic tendencies between donor and recipient, patterns of gift-giving provide an insight to the strength of ties an individual holds with different members of their social network. In this study, patterns of Christmas gift-giving were used to test between three hypotheses for the origins and function of females’ friendships. As well as demonstrating that gift value fell in a linear fashion with coefficient of relatedness, conforming to the expectations of Hamilton’s rule, the results show striking gender differences. While gifts of similar value were bought by males and females for close kin, spouses, and close social network layers, females spent significantly more than males on distantly related kin, friends and individuals in more peripheral social network layers. These results are best explained by the hypothesis that womens’ relationships reflect a need to replace the loss of female matrilineal relatives (a consequence of patrilocality), and that the psychology underpinning this continues to act in modern environments.

54 122 Differences in threat perception between high and low socially anxious observers Antonio A. Álvarez, University of Santiago de Compostela, [email protected] Although, in the normal range, some forms of anxiety can be functional, differences between high and low anxious people have been found to appear when the information to be processed is slightly threatening, but not crucial for survival. To investigate that premise, 172 undergraduates of the University of Santiago de Compostela (Spain), were assigned to a high or low social anxiety group, according their scores in the BFNE, and asked to rate on a 9-point scale the threat conveyed by each of 31 slides of the IAPS (e.g., people or animals). No significant differences were found between the anxiety groups in their threat ratings (ThR) to threatening images (ThR > 5). However, the high social anxiety group rated the non-threatening slides (ThR ≤ 5) significantly more menacing than the low social anxiety group. These results suggest that social anxiety is a dysfunctional response.

123 Individual differences in female mating behavior Candace Black, University of Arizona, [email protected] Emily Patch, University of Arizona, [email protected] Previous analyses of female mating attitudes, preferences, and behavior have been limited in their consideration of individual differences factors such as life history. The current study specifically examines the role of life history strategy in predicting outcomes using several metrics commonly employed in this area of study. We will present data showing the role of individual differences in the influence of hormonal changes across the ovulatory cycle that may account for variation in female sexual behavior, attitudes toward love and relationships, and preferred characteristics in mates.

124 Estimation of opposite sex's sexual impact felt from mild sexual picture of young girl: Accurate or not? Kazuaki Kawano, Tokai-Gakuen University, [email protected] Takashi Hanari, Sugiyama Jogakuen University, [email protected] Kimio Ito, Tokai-Gakuen University, [email protected] Ability to read the visual sexual impact on each sex might be very important in actual mate acquisition negotiations, for example, competition with sexual rivals and promotion of sexual appeal. This study aimed to clarify the degree of accuracy in estimating the sexual impact on a person of the opposite sex given by mild sexual visual stimulus. Forty-eight pictures of young girls with various degrees of skin exposure were prepared as a mild sexual stimulus. These were randomly projected on a screen. Student participants were asked to evaluate the sexual impact they felt from each picture, then estimate the general impact felt by same sex persons and opposite sex persons on a scale of 0-10. As expected, the total impact felt by males was higher than that of females, and the correlations among impact on self and estimations for the same sex and opposite sex were high. However, females overestimated impacts on males, especially for pictures with much skin exposed, and males estimated the opposite sex person's impact more accurately than females did. Functional implications of the results are discussed.

125 General fitness or life history strategy? Evidence for a substantial association between the general factor of personality and general intelligence Curtis Dunkel Western Illinois University, [email protected] Despite theoretical assertions derived from life history theory and the theory of general fitness, research on the relationship between the General Factor of Personality and general intelligence has shown that there is little overlap between the two higher-order constructs. It is argued that the association between these general factors is largely attenuated by measurement error in assessing the General Factor of Personality. A substantial association between the general factors at multiple points in time was found when the General Factor of Personality was derived from rater Q-sorts. The results have important implications for the study of individual differences.

Culture

126 The relationship between pathogen prevalence and the solution to free-rider problems Yutaka Horita, Hokkaido University, [email protected] Masanori Takezawa, Hokkaido University, [email protected] It is argued that risk of infectious diseases was one of the strong selection pressures for humans and collectivistic culture promoting group cooperation emerged as an evolutionary adaptation for defending groups against diseases infections (Fincher et al, 2008; Gelfand et al, 2011; Murray et al, 2011). However, group cooperation inherently contains the free- rider problem and some mechanisms for solving the problem must have co-evolved in response to the selection pressure of infectious disease. Our analyses of the World Values Survey Data and cross-cultural studies of experimental games (e.g., Herrmann et al, 2008) revealed that people living in higher historical pathogen prevalences were more sensitive to evaluation by close others and have stronger punitive tendencies. These results suggest that psychological mechanisms for suppressing the free-rider problem emerged together with the tendency to cooperate for a group.

55 127 Culturally contagious non-replicators Luke McCrohon, Cerego Learning Technologies Ltd., [email protected] Dawkins’ (1976) concept of a meme, a replicating unit of cultural information analogous to a biological gene, has been influential in the development of a number of theories of cultural evolution (e.g. Hull 1988, Blackmore 1999). However, despite its widespread usage in the literature, there currently exists no universally accepted definition of what constitutes a meme (Rose 1988). The suggested ability of individual memes to combine to form ‘coadapted meme complexes’, or ‘memeplexes’ (Speel 1995), has only added to the confusion surrounding the term. In this paper I consider a particular class of culturally transmittable phenomenon, including Obesity (Hill et al. 2010), Happiness (Fowler & Christakis 2008) and Suicide (Bearman & Moody 2004), which despite being transmittable, are argued not to be memes. Rather than being replicators, it is argued that these phenomena represent cultural phenotypic traits, that result from a range of distinct underlying memetic behavioural mechanisms. Similarly, they are argued not to be memeplexes as they generally result from individual memes acting in isolation without the possibility of coadaptation.

128 Explaining human behavioral diversity: Temporal changes in the geographical patterns of age at first marriage in Japan Kohei Tamura, The University of Tokyo, [email protected] Yasuo Ihara, The University of Tokyo, [email protected] Human beings exhibit considerable behavioral diversity, which is partly explained by adaptation to local environments and cultural random drift. The average age at which women have their first child varies across societies. Evolutionary theory predicts that the age of onset of female reproduction should be sensitive to variation in mortality rates, so that the variations in reproductive timing are expected to be related with the variations in local ecology among societies. Previous studies showed that geographical patterns in age at first marriage and family size are explained by local adaptation. In the present study, using demographic data, we analyze the temporal change of the geographical patterns. Based on the results, we discuss the relationship between cultural transmission and ecological adaptation.

129 Gender and race gaps in academic achievement: Culture and life history approaches Carlos David Navarrete, Michigan State University, [email protected] Although not widely known, female students attain higher GPAs in school, take more challenging course loads, graduate high school at a higher rate, and receive college degrees at a much higher rate than male students. Women also are expected to account for the majority of the workforce in most professional fields in the near future. The gender gap in academic achievement may be even greater among Latino and African Americans, which may pose challenges for the economy and our shared understanding of justice and equality. This study examines the potential for multiple causes along two lines (1) culturally evolved concepts that may differ between ethnic groups such as “macho” attitudes and educational aspirations, and (2) life history variables such as onset of puberty, sociosexuality, and risk sensitivity. Data from two studies on college and high-school students were used to investigate the roles of cultural and biological inputs as predictors of academic achievement. Cultural machismo and risk sensitivity yielded replicable and reliable effects on explaining gender and race gaps in academic achievement. Implications are discussed.

130 The cultural evolution of emergent group-level traits Paul E. Smaldino, Johns Hopkins University, Center for Advanced Modeling the Social, Behavioral, and Health Sciences, [email protected] Many of the most important properties of human groups – including properties that may give one group an evolutionary advantage over another – are properly defined only at the level of group organization. Yet most work on the evolution of culture has focused on the transmission of individual-level traits. In contrast, group-level traits emerge from the structured organization of differentiated individuals, and constitute a unit of selection that is qualitatively different from selection on groups as defined by traditional multilevel selection theory. I will discuss the emergence and evolution of group-level traits, and implications for the theory of cultural evolution, including ramifications for the evolution of human cooperation, technology, and cultural institutions, and for the equivalency of multilevel selection and inclusive fitness approaches.

131 Cultural transmission in information cycles Thomas Abel, Tzu Chi University, [email protected] Culture is produced in ‘information cycles’ and thus cultural transmission is the result of these cycles. The ‘information cycle’ is a general model of the production and maintenance of information of any kind. Maintenance is the missing component in most theorizing about culture. Culture does not exist in abstraction, but is always ‘carried’ by some energy or material. It is thus subject to Second Law depreciation, and requires continual cycles of renewal. The copying of information is prone to error, however, due to the fragility of carriers. Thus in renewal, multiple copies are made and dispersed, followed by future selection. The information of culture is not produced or transmitted continuously and it is not produced solely in conversation. Instead, culture is produced in production processes that differ in their inputs, duration, and space. This experiment explores the transmission of culture in information cycles of media, education, conversation, et al.

56 132 Copying error and the cultural evolution of ‘additive’ versus ‘reductive’ material traditions: An experimental assessment Kerstin Schillinger, University of Kent, [email protected] Alex Mesoudi, Durham University, [email protected] Stephen J. Lycett, University of Kent, [email protected] Just as genetic mutation is a fundamental component in biological evolution, recent cultural evolutionary models suggest that undirected copying errors can generate distinct patterns of variation and change in human artifactual traditions (i.e. “material culture”). However, to date, no experimental work has been undertaken to examine how different physical manufacturing techniques can affect this copying error. 60 participants used either reductive (removing material) or additive (adding material) manufacturing processes to create physical 3D plasticine replicas of Acheulean handaxes. Reductive processes, such as those applied in the manufacture of Paleolithic stone tools, led to significantly (p=.019) greater shape copying errors than ‘additive’ processes, as used in pottery or basketry traditions. Overall, these results demonstrate that contrasting physical manufacturing traditions alone can differentially affect the generation of cultural variation and, ultimately, the evolution of shape ‘traditions’ in material culture. Moreover, our results highlight the value of experiments in studying material cultural evolution.

133 Fertility, convergence, and universal cultural traits J. Alex Kevern, Northwestern University, [email protected] Human Universals are a useful tool for examining the relationship between the biological and social basis of behavior. Typically the universality of a cultural trait is taken as evidence that it is biological or innate. I offer an alternative explanation; that particular human universals could potentially be a result of parallel cultural processes that operate primarily though a correlation with fertility. I identify three processes: gene-culture convergence, cultural convergence, and group selection, each of which could potentially play a key role in explaining the presence of a subset of human universals in cultural terms. I maintain the possible role of biological predispositions, but stress the interaction between biology and culture through critical periods of human development and social learning. I conclude that human universality does not necessitate biological innateness, and invite more work on exploring the cultural evolutionary origins of the traits all human societies share.

134 Historical trends in rank and status Paul Dachslager, [email protected] The psychology of status and rank is an important discipline within evolutionary psychology. It is also important in the history of philosophy and politics. This paper will analyze this history with the techniques of EP. Historically, military prowess, and mind and reason were viewed as the most important aspects of human nature. As the faculty of higher assessment, as shown by math, reason was viewed as the natural overseers of the appetites. Following Plato, this created a social value system that viewed ascetic people as more respectable than hedonists, and thus more fit to rule both in terms of interpersonal relations and politics. From the early modern period to about the early twentieth century, patterns of deference were established along these lines. With sexual liberation and the revolt against reason, these patterns of deference were inverted, and now ascetic people are viewed as suspect, and so the ideal is that the “uptight computer geeks” have to defer to their more natural, athletic superiors.

135 Impacts of institutional changes in Cambodia under the Pol Pot Regime Katsuo Kogure, Hitotsubashi University, [email protected] We study impacts of the communist revolution by the Khmer Rouge (1975-'79) in Cambodia on economic behaviors of survivors after 1979. We focus on forced marriage, which resulted from the complete denials of private ownerships under the Pol Pot regime. Using the 1998 Census micro-data, we compare forced marriages in the Pol Pot regime with regular marriages after its collapse, and make econometric evaluations of their educational investments for children. Our results suggest that forced-marriage couples invested less in their children's education than the regular-marriage couples. We consider those results, by reflecting upon social and political structures of Cambodia under and after the Pol Pot regime. We present evidence suggesting that forced-marriage couples tend to behave so as to conform to the rules of the Pol Pot regime relative to regular-marriage couples. The persistency of those differences differs among regions with different political structures.

57 Theory and Applied

136 Field-friendly methods for measuring immune function in behavioral ecology and evolutionary psychology Angela Garcia, University of California Santa Barbara, [email protected] Aaron Blackwell, University of California Santa Barbara, [email protected] Pathogens have played an important role in selecting both behavioral and physiological responses in humans, and much recent work in both behavioral ecology and evolutionary psychology examines the role of pathogens and immune function as key life history parameters. However, simple measures of white blood cell count obscure significant interpersonal and cross-cultural variation in white blood cell repertoires. At the same time, measuring immuno-phenotypes in a field setting presents several obstacles. Flow cytometry, a technology for cell counting, sorting, and biomarker detection is a useful tool that allows us to look at indicators of innate and adaptive immunity. However, flow cytometry is usually done on fresh blood and porting a flow cytometer to the field is costly and risky. Instead, here we develop and report on techniques for preserving field samples for later analysis in a university laboratory. The same technique can be used to collect samples in psychological experiments using simple finger pricks, without the pressure to analyze fresh samples immediately.

137 Reversal of fortune: Evolutionary reward release rules and social inequality Michael Hammond, University of Toronto, [email protected] In other highly status sensitive primates, such as the chimpanzee, there is a high tolerance for the repetition of the same actions with the same individuals. Neurochemical and other body rewards continue to be released during this high repetition. The result is the consistent emergence of elevated status differentiation. In humans, there is a lower tolerance and less reward release for such repetition. In our context of origin with its micro populations, this adaptation helped to dampen the expansion of inequality in most circumstances. Only occasional situations offered an expanded variety of triggers for additional reward release, usually on a temporary basis. With the exodus and its expanded populations, the balance of power shifted from the dampening repetition rules to the inequality fueling variety release rules. The occasional and the temporary became the permanent norm. This triggered additional reward release on a long-term basis, and inequality exploded. It was only much later in our history that other means were found to trigger such additional release from other interests, making possible the partial reversal of inflated inequality in some of its forms.

138 Media naturalness theory and human social bonding Tatiana A. Vlahovic, Carnegie Mellon University, [email protected] Sam G. B. Roberts, University of Chester, [email protected] Robin I. M. Dunbar, University of Oxford, [email protected] Kock’s Media Naturalness Theory advocates that humans have evolved adaptations for face-to-face (FTF) interaction, and interaction through less “natural” communication modes (i.e., those possessing less qualities of FTF interaction) will be linked to elevated cognitive effort, elevated communication ambiguity, and reduced physiological arousal. Happiness and laughter are important regulators of human interactions and social relationships. In this study, 41 participants completed a 14-day time diary tracking their social interactions with up to five communication partners across six communication modes: FTF, Skype videoconferencing, phone, instant messaging, text messaging, and emails/social networking site messages. While FTF and Skype videoconferencing did not differ from each other, both happiness ratings and occurrence of laughter were higher for FTF and Skype videoconferencing in comparison with other communication modes. These findings support Media Naturalness Theory and suggest that more natural communication modes, particularly modes with both verbal and non-verbal signals, may support human social interactions and relationships more effectively.

139 Exploring inconsistent condom use from an evolutionary perspective Jocelyn Wentland, University of Ottawa, [email protected] Elke Reissing, University of Ottawa, [email protected] Catherine Plowright, University of Ottawa, [email protected] Evidence of condom use spans our historical records, yet, from an evolutionarily perspective, condoms represent a modern invention. Several proximate causes have been advanced to explain inconsistent condom use (alcohol use, loss of sensation, personality), yet condom use has not been extensively informed by evolutionary considerations. Cues to problems from our ancestral past (desire to procreate, identify and secure mates, maximize mate-retention, minimize cuckoldry) may influence current condom use patterns. This review will examine two specific lines of evolutionary evidence in regards to condom use: biological (Good Genes theory, anti-cuckoldry tactics, biological components of semen) and non-biological evidence (female choice of partners, threat of violence, and reputation concerns). What used to offer multiple advantages to the survival of individuals and their offspring in the past (engaging in intercourse to secure a partner or ensure survival of one’s genes) may be maladaptive today in regards to reproductive fitness (STIs, HIV/AIDS). Incorporating evolutionary explanations for inconsistent use may provide additional insight into the existing condom use literature.

58 140 A model of family functions Ani Bajrami, Faculty of Natural Sciences, [email protected] Zyri Bajrami, Faculty of Natural Sciences, [email protected] This study takes in consideration ratings about marriage and family and their relation to well-being, children, family harmony and erotical pleasure. We analyzed 212 individuals (students), their parents (241 individuals) and one of their grandfather (179 individuals). The collected data have made possible the construction of a simple mathematical model, which analyzes the four ratings mentioned above and their relation in time. This mathematical model is expressed as follows: E/F = M/ 1-H. It shows that during the evolution of human populations, the high ratings of sexual pleasure are in inverse proportion with the desire of having children. For example, grandfathers value the desire of having children 44% while students value this parameter only 25.8%. On the contrary, students value erotical pleasure 28.4% and their parents value this parameter only for15.3%.

141 Taking the nuclear trap in evolutionary theory seriously James Rutherford, Grant Hospital, Columbus, OH, [email protected] The nuclear trap points to a concern that our technological advances, with the development of weapons of mass destruction, may have exceeded the ability of our evolutionary adaptive moral behaviors to manage them. The nuclear arsenals for the last fifty years, for example, have been large enough to potentially create a nuclear winter with the destruction of most of life on earth. During most of that time we have had a defense policy of mutual assured destruction. One approach to establishing a more stable world order in a pluralistic global community would be to use our available resources to promote a moral assertion of a respect for human dignity and our common humanity. Another would be to begin to address the global political uses of violence by abolishing the death penalty in the United States.

142 Transhumanism and scientific obligations Chris Freire, Florida State University, [email protected] Transhumanism says that the goal of biomedical technology is to progress to the point where human life and cognitive/physical abilities are extended and improved as much as possible. Some object by claiming that threats to personal identity make transhumanist goals misguided at best, and highly unethical at worst. I will object to this criticism by explaining the development of transhumanist technologies in the context of the role of science in society. I will begin by establishing the possibility of retaining personal identity through transhumanist medical procedures. I will then explain that this possibility, and the freedom for individuals to choose for themselves whether or not to use transhumanist technologies, is all that is needed for transhumanism to be a legitimate scientific goal. I will then contrast two possible worlds, one with transhumanist technologies, and one without; to show that the former is clearly preferable to the later. I will conclude by explaining that these transhumanist goals as the only plausible position when considering the future of biomedical technologies.

143 Anonymity and gender: How privacy influences self-reports of sexual behavior on the internet Melanie Beaussart, California State University, San Bernardino, [email protected] James Kaufman, California State University, San Bernardino, [email protected] The commonly held belief about the biologic foundation of gender differences in sexual behavior has been challenged by those who suggest that these results stem from cultural biases that reinforce gender stereotypes. The use of the Internet for conducting research has found that the level of anonymity intrinsic to web-based surveys is useful in deterring these kinds of participant biases. However, concerns about Internet privacy could interfere with the effects of perceived anonymity and influence how a person responds. In this study, participants were asked to take an Internet survey and then were randomly assigned to conditions with varying degrees of implied privacy in which they answered questions about their sociosexuality and sexual behavior. It was shown that gender-biased reporting of some sexual information was mediated by the level of anonymity the participants perceived and that this effect differed for men and women. Though gender differences in sociosexuality were consistent across conditions, self-reports of sexual behavior was not. Results are discussed as an interaction of socialization within an evolutionary context.

144 Categorizing evolution: Natural, cultural and political perspectives Kathleen Bryson, University College London, [email protected] We often pigeonhole our surroundings into dualistic categories i.e. white/black, nature/culture. Were evolutionary forces at work that favoured dichotomous brains - because those who simplified were better equipped to survive and reproduce? My research will concentrate on four classic alterities (Human/Animal, Male/Female, Heterosexual/Homosexual, Body/Machine) oft-cited in biological anthopological studies, aiming to reconstruct the developmental forces that can bring about, stabilize or modify binarism. I will explore the rigidity of the exemplary alterities by gathering data on boundary perceptions from 16 years of UK newspaper reporting (1995-2001). I will investigate if and how such boundaries are subject to change, potentially reflecting iconic chronological events (the Millennium; 9/11) or scientific discoveries. My research is therefore situated in discourses that encompass philosophy of science, evolutionary theory and media studies. A multi-disciplinary approach is challenging, but also has the potential for innovative thought. Hopefully, the ensuing gradualist paradigm will reveal how dichotomous thinking influences scientific narratives.

59 145 A collision of worlds: Feminists’ perceptions of evolutionary psychology Laura Cowan, Texas Woman’s University, [email protected] Linda Rubin, Texas Woman’s University, [email protected] There have been mixed reactions to the burgeoning existence of evolutionary psychology as a framework for understanding human behavior within the field of psychology. Perhaps one of the most visible and consistent movements to criticize evolutionary psychology has historically been feminism. While there has been discussion in the literature of feminist critiques of evolutionary psychology, social scientists have not yet systematically examined the impact of psychologists’ feminist attitudes on their perceptions of evolutionary psychology. To investigate these relationships, this study compared 88 women psychologists’ identification with various aspects of feminist theory and their perceptions of evolutionary psychology. Participants responded to a demographic questionnaire, three subscales of the Feminist Identity Development Scale (FIDS), as well as researcher-generated questions about perceptions of evolutionary psychology. Results were examined with regression analyses. Findings are discussed in terms of future research and potential for theoretical integration.

Physiology

146 Fertility cues in female bodies: Estrogen predicts attractiveness after controlling for BMI Rachel Grillot, University of California, Santa Barbara, [email protected] Adar Eisenbruch, University of California, Santa Barbara, [email protected] James Roney, University of California, Santa Barbara, [email protected] Converging evidence supports the notion that human female physical attractiveness may be an honest index of reproductive capacity. Prior research has demonstrated that breast size and low waist-to-hip ratio are positively associated with estrogen and progesterone. This study sought to replicate the relationship between ovarian hormones and morphological features, and investigate their effects on physical attractiveness in naturally-cycling women. Daily saliva samples were collected across 1-2 menstrual cycles and assayed for estrogen, progesterone, and testosterone. Contrary to previous research, estrogen and progesterone were not significantly correlated with breast size or waist-to- hip ratio, though testosterone did positively correlate with breast size. Body attractiveness was negatively correlated with BMI, but was not significantly associated with either breast size or waist-to-hip ratio independent of BMI. Most importantly, mean estrogen levels did predict body attractiveness ratings after controlling for BMI.

147 My microbes are depressing: A meta analysis Clemens Janssen, University of Arizona, [email protected] Triin Anton, University of Arizona, [email protected] The gastrointestinal tract in humans consists of a vast microbial community that has coevolved with us over the past 500 million years. This process has resulted in the development of some symbiotic relationships that involve bidirectional communication between the brain and gut (Grenham et al., 2011). Fresh attention has focused on how microbes can influence the brain and behavior including a 12-year prospective study that found that people who had no psychological symptoms (but elevated functional gastrointestinal disorders) at baseline, experienced significantly higher levels of anxiety and depression 12 years later (Koloski et al, 2012). The current meta-analysis combines the results from 4 additional, independent studies using a probiotic intervention for gastrointestinal disorders that included a measure of depression (total N=112). A robust mean effect size of r=.424 was found for the reduction in depressive symptoms although psychological intervention was not part of the studies. This effect provides support for the influence of coevolved microorganisms on human behavior.

148 Social evaluative threat's influence on the immune response Nicolas M. Jordan, Oklahoma State University, [email protected] Jessica L. Calvi, Oklahoma State University, [email protected] Brandon J. Auer, Oklahoma State University, [email protected] Jennifer Byrd-Craven, Oklahoma State University, [email protected] The current study examined sex differences in social evaluative threat as a stressor on the immune system as a part of the broader stress response system. An increase in inflammatory response was measured non-invasively through interlueukin-1 beta (IL-1B). Participants enrolled in university speech classes gave saliva samples before (pre-task), immediately following (post-task 1), and 20 minutes after (post-task 2) a course-required speech. Participants completed questionnaires on social anxiety and rejection sensitivity. Area under the curve changes in IL-1B indicated that for males, both the social anxiety and rejection sensitivity were significant predictors of immune system responding; however, neither were significant predictors for females. Males showed an overall increase in IL-1B at post-task 2, whereas females continued to drop in IL-1B responding. Results suggest an immune response to a social evaluative threat for males that may be reflective of an evolved response to social threats.

60 149 Perceived facial attractiveness and perceiver’s mate value interact to capture the central processing resources of the perceiver: An event-related brain potential (ERP) study Laura Morgan, University of Colorado, Colorado Springs, [email protected] Michael Kisley, University of Colorado, Colorado Springs, [email protected] Attractive faces capture cognitive resources in a proportional manner: more attractive faces capture more resources. But to be adaptively valuable this relationship should also be modulated by properties of the perceiver including mating market value. Here we investigated the allocation of processing resources towards female faces (attractive and unattractive), and manipulated market value within a sample of men (N=30). A specific event-related brain potential component, the late positive potential (LPP), was measured to track resource allocation to faces. Men were told they were rated as a 3 out of 8 on average (low perceiver market value) or as a 7 out of 8 (high value). Attractive female faces were associated with the largest LPP response amplitudes across conditions (p < .001). However the perceiver’s market value and target face attractiveness interacted (p < .05), as brain responses to unattractive faces were significantly larger in the low market value condition than in the high market value condition. In other words, men in the high market value condition devoted few if any processing resources to unattractive faces.

150 The effects of sleep deprivation on sexual behavior and decision-making Jennifer Penner, Hendrix College, [email protected]; Jennifer Peszka, Hendrix College, [email protected] Lauren Stansbury, Hendrix College, [email protected]; Izzy Anderson, Hendrix College, [email protected] Lacy Cunningham, Hendrix College, [email protected]; Andre Leonard, Hendrix College, [email protected] Nicholas Jordan, Hendrix College, [email protected] The frontal lobe is known to contribute to decision-making, risk assessment, and social and moral reasoning, all of which are presumably involved in human reproductive behavior. We examined the contribution of the frontal lobe in the sexual and romantic behavior of healthy college-aged men and women (N=38) by sleep-depriving them, a manipulation known to impair prefrontal functioning. We observed behavior during and measured self-reported sexual interest immediately after speed-dating interviews that occurred before and after 36 hours of supervised sleep deprivation. Sleep-deprived participants (compared to their baseline responses) reported a higher likelihood of having sex with their speed-dating partner (p<.05), sat closer to their partner (p<.05), were more likely to ask questions related to sexual interest (p<.05), and were less likely to ask questions related to long-term mating (p<.05). These, among other findings (including measures of prefrontal functioning), indicate that the frontal lobe may, in part, manage sexual decision-making and mate evaluation in young adults and that it may do so differently for men and women.

151 Expectations for interaction type affect level of oxytocin Rick O’Gorman, University of Essex, [email protected] Jayakumar Mani, University of Essex, [email protected] Nelson Fernandez, University of Essex, [email protected] Essam Elzatma Oxytocin has been linked recently with having an important role in social relationships, in particular facilitating cooperation and trust. We have recently conducted studies examining the response levels of oxytocin in social interactions where there were differing expectations regarding the nature of an interaction: Participants attended for a lab session with prior knowledge that they would either interact with a friend face-to-face, or via a Facebook account. We measured oxytocin via saliva samples. Results show that the simple anticipation of the nature of the interaction affects the level of oxytocin. A follow-up study examined more extensively whether anticipating the nature of the interaction (with a friend or stranger) or simply whether a friend would be present (but not interacted with) drove differences in oxytocin, as well as examining whether differing levels affect decisions in economic games. Results for this study will be available for the conference.

152 The relationship between digit ratio and interhemispheric transfer time Wilmon Brown, III, Oklahoma State University, [email protected] Rachel Messer, Oklahoma State University, [email protected] Sheila Kennison, Oklahoma State University, [email protected] The research investigated whether prenatal exposure to androgens would be related to how quickly information is transferred between the hemispheres of the brain. The participants in the study were 31 students enrolled in courses at Oklahoma State University. Participants completed the IHTT task (Savage & Thomas, 1993). Later, the lengths of their fingers on each hand were measured using a digital caliper. According to the data that was collected, the IHTT is related to digit ratio on the right hand for both men and women, but in opposite directions. For women, smaller digit ratio on the right hand is related to longer IHTT (r=-.496, p=.05). For men, smaller digit ratio on the right hand is related to shorter IHTT (r=+.659, p =.03). The results supported the hypothesis that digit ratio would be related to IHTT. They further indicated that the relationship differed for men and women. Prenatal exposure to androgen appears to slow IHTT for women but facilitate it for men. The relationship between digit ratio and IHTT has future implications that digit ratio may be an external physiological indicator of other cognitive processes, such as learning.

61 153 The neurophysiology of perceived attractiveness Valerie Starratt, Nova Southeastern University, [email protected] Jaime Tartar, Nova Southeastern University, [email protected] Glenn Scheyd, Nova Southeastern University, [email protected] The goal of this study is to investigate the neurobiological mechanisms underlying the evolved psychological mechanisms relevant to human mate attraction. Electroencephalographic (EEG) event related brain potentials (ERPs) are used as the primary index of the influence of target facial attractiveness on neurobiological processing. Salivary testosterone levels are also assessed to determine the influence of mating-relevant hormones on these processes. Measures of personality and sociosexual orientation are included to identify the effects of psychosocial individual differences on neurobiological responsiveness to perceived attractiveness.

154 The evolution of Hominin shoulder orientation; A retrospective analysis of scapular glenoid orientation spanning 400 Million years Ashley Iain Simpson, Royal Berkshire Hospital, [email protected] Flora Gibbons, University of Oxford, [email protected] Fritz Vollrath, University of Oxford, [email protected] Paul Monk, University of Oxford, [email protected] Jonathan Rees, University of Oxford, [email protected] Introduction: Bipedalism has resulted in dramatic changes in shoulder morphology. This study describes evolutionary changes in glenoid version and inclination in terms of locomotor strategies. Method: Natural History Museums of London and Oxford and the University of Oxford provided specimens spanning 400 million years. Scapulae were imaged using a 64-slice CT scanner. 3D reconstructions were segmented using validated AMIRA software. Glenoid version and inclination were described relative to the scapular plane. Results: Modern hominins possess caudally oriented and retroverted glenoid fossae. This contrasts with fossils from 2 Mya, e.g. Homo ergaster possess cranially oriented and anteverted fossae. Recent brachiates, Gorilla gorilla and Pan troglodytes, demonstrate progressive anteversion, while ancient quadrupeds, e.g. Anathana, display significant anteversion and caudal orientation. Conclusion: Hominin scapular fossae demonstrate morphology either incompletely adapted to obligate bipedalism or evolved for infrequent arboreal utilisation. Modern hominins display progressive scapular evolution adapted for load carrying and forelimbs operating within a binocular visual field.

155 Cumulative estrogen exposure, number of menstrual cycles, and Alzheimer’s risk in a cohort of British women Molly Fox, University of Cambridge, [email protected] Carlo Berzuini, University of Manchester, [email protected] Leslie Knapp, University of Cambridge, [email protected] Variation in female reproductive life-history has physiological implications. There may be long-term health consequences of cumulative hormone exposures. The effect of estrogen on Alzheimer’s risk has received substantial research and media attention, especially in terms of hormone replacement therapy. But reproductive history is also an important modifier of estrogenic exposure, and deserves further investigation. We measured degree of Alzheimer’s-type dementia in a cohort of elderly British women, and collected detailed reproductive and medical history information, which we used to estimate number of months with estrogen exposure and number of months with menstrual cycles. We build upon previous methodologies by taking into account a variety of parameters including oral contraceptive use, breastfeeding, post-partum anovulation, abortions, and miscarriages. Our results indicate that longer duration of estrogen exposure and higher number of menstrual cycles may be associated with lower Alzheimer's risk.

156 Testosterone administration rapidly modulates threat-related neural function Stefan Goetz, Wayne State University, [email protected]; Lingfei Tang, Wayne State University, [email protected]; Moriah Thomason, Wayne State University, [email protected] Michael Diamon, Wayne State University, [email protected] Justin Carré, Wayne State University, [email protected] Mazur (1985) proposed that changes in testosterone during competition would function to promote dominance behaviors. Indeed, recent evidence indicates that testosterone reactivity to competition maps onto subsequent aggression (Carré et al., 2011). Despite these findings, strong causal inferences cannot be made because testosterone was not experimentally manipulated. Here, we developed a pharmacological challenge paradigm to test the role of testosterone on the functioning of threat-related neural circuitry. In a placebo-controlled, double-blinded crossover design, men received a GnRH antagonist to suppress and reduce variability in testosterone and then received testosterone gel (or placebo). Next, participants performed an emotional face-processing fMRI task. Testosterone increased centromedial amygdala, hypothalamic, and periaqueductual grey reactivity and decreased OFC reactivity to angry faces. These findings indicate that testosterone rapidly modulates the neural circuitry underlying aggression, and thus provides a neurobiological mechanism underlying the effect of competition-induced testosterone reactivity on aggressive behavior.

62 Miscellaneous

157 Self-deception and illusions of control Charlotte Wilkin, Bangor University, [email protected] Robert Ward, Bangor University From an evolutionary perspective, the function of self-deception is to better deceive others to gain resources (Trivers & von Hippel, 2011). The proposal of a dissociation allowing simultaneously held, contradictory beliefs is under researched. We investigated whether explicit reports of control, demonstrated by an illusion of control (IOC, Alloy & Abramson, 1979), were dissociated from other accurate knowledge of environmental probabilities. 52 participants completed a 100-trial task, in which two responses (space bar press/no-press) and two outcomes (reward=green light; no reward=no light) were noncontingently related, i.e., no control. Participants estimated their control, and the conditional probabilities of reward. On a subsequent 10-trial task, they attempted to maximise reward based on their knowledge. Participants demonstrated a significant IOC, whilst accurately estimating the conditional probabilities. Although reward was randomly determined, about half of participants, by chance received more reward for responding than not responding. For these participants, subsequent performance was based on the inaccurate IOC, rather than the accurate knowledge of contingent reward. Participants demonstrated two forms of knowledge: an inaccurate report of inflated actual control; and accurate knowledge of the conditional probabilities. Yet it was the inaccurate report that guided subsequent behaviour in participants who were rewarded for responding. Our results demonstrate a form of self-deception even when accurate contradictory evidence is available.

63 Keynote Address

Americana Salon 3/4 Saturday, July 20, 7:30 PM Keynote Introduction John and Leda: An Appreciation Steven Pinker Johnstone Family Professor Department of Psychology Harvard University

Americana Salon 3/4 Saturday, July 20, 8:00 PM Keynote Address Evolutionary Psychology: Back to the Future Leda Cosmides & John Tooby Co-Directors, Center for Evolutionary Psychology University of California Santa Barbara

64 Plenary Abstracts

Americana Salon 3 Wednesday, July 17, 3:00PM

The rational animal: Fundamental motives and behavioral economics Douglas T. Kenrick, Professor of Psychology, Arizona State University On the classic view, human beings are eminently rational, processing immense amounts of relevant information to make carefully honed self-serving decisions, and to do so in consistent ways. During the late 20th century, that view was challenged by evidence from behavioral economists, who uncovered abundant evidence of irrational, inconsistent, short- sighted, and self-defeating decision-making. In this talk, I’ll present evidence for a third view - - that our decisions manifest what my colleagues and I call Deep Rationality. On this view, human decisions are biased, but those biases are not random and self-defeating. Instead, they are calibrated to evolutionarily relevant contexts. Biases such as loss aversion, which behavioral economists have taken as iconic examples of irrationality, actually wax and wane in functionally sensible ways, depending on currently active fundamental motives and other relevant life history variables.

Americana Salon 3 Wednesday, July 17, 7:30PM

Grandmothers and grandfathers among the Yanomamö Napoleon Chagnon, Professor of Biosocial Anthropology, University of Missouri & University of California, Santa Barbara The anthropological interest in grandparents over the past 25 years among evolutionary- minded field researchers has increased steadily since Hawkes (Hawkes et al 1989; Hawkes et al 1997) and Hrdy (1999). There have been a number of important papers on this topic across the biological and social sciences and a useful summary of this literature can be found in Coall & Hertwig (2010). The majority of this literature has focused specifically on grandmothers. My paper will focus on grandfathers among the Yanomamö and how their efforts to aid grandchildren in fitness enhancing ways other than provisioning of food or pathways leading to reduced child mortality. The primary focus of this paper will be on the possible effect of grandfathers on their male agnatic descendants’ marriage success and whether these male descendants are coresidents in the grandfather’s local group. The paper also will analyze the distribution by 5-year age categories of the percentage of the population having living co- resident grandfathers. A major question is: “How many people have coresident grandfathers (and grandmothers) in their local group, a figure that decreases by age of the individual and by the rate of community fissioning into smaller, widely dispersed groups?” This paper is will be the first one that incorporates new data that the senior author collected in Yanomamö villages in the remote Siapa River Basin and will have several co-authors.

65 Americana Salon 3 Thursday, July 18, 9:00AM

Early sociomoral reasoning Renée L. Baillargeon, Alumni Distinguished Professor of Psychology, University of Illinois at Urbana-Champaign Investigators have recently begun to examine what expectations infants and toddlers possess about social interactions among individuals. One objective of this research has been to uncover what sociomoral principles might guide these early expectations. My collaborators and I have been exploring infants’ and toddlers’ expectations about three candidate principles in particular: Reciprocity, Fairness, and Ingroup. Our experiments use third-party situations involving primarily novel, arbitrary groups. Our results suggest two main conclusions. First, infants and toddlers generally expect interactions among individuals to unfold in accordance with the principles of Reciprocity, Fairness, and Ingroup. Second, significant developments occur as infants learn to order competing expectations from different principles to reflect the orderings selected by their social environment. These findings help shed light on the developmental origins and causal etiology of adult intuitive moral reasoning.

Americana Salon 3 Thursday, July 18, 2:00PM

Investigating face processing through deficits and disruptions Brad Duchaine, Associate Professor of Psychology, Dartmouth Face processing has received extensive research attention over the last 30 years, and as a result, our understanding of its cognitive, neural, and developmental basis is better understood than most other complex neurocognitive systems. Fundamental issues however remain unclear, and in this talk, I'll discuss results from developmental prosopagnosia, acquired prosopagnosia, and transcranial magnetic stimulation that shed light on some of these issues.

Americana Salon 3 Friday, July 19, 9:00AM Hunter-gatherer infancy and childhood in the context of human life history evolution Melvin Konner, Samuel Candler Dobbs Professor of Anthropology, Emory University In the 1970s studies of infancy and childhood among !Kung (Zhun/twasi) hunter-gatherers of northwestern Botswana yielded a distinctive characterization of their patterns of child care and behavioral development, and surveys of prior ethnographic literature suggested that core features of these patterns were seen in other hunter-gatherers. Over the past four decades excellent quantitative studies of various aspects of infancy and childhood in at least eight other hunting-and-gathering, partly hunting-and-gathering, or recently-hunting-and- gathering groups have made systematic comparisons possible. They have also led to challenges to the !Kung-derived Hunter-Gatherer Childhood (HGC) model, which may be summarized as the Childhood as Facultative Adaptation (CFA) model; it suggests that important features of hunter-gatherer childhood (e.g. degree of allocare, weaning age, indulgence of care, and how much children contribute to subsistence) vary so much with

66 local ecological and demographic conditions that no generalizations are possible. This lecture considers these challenges, defends a modified version of the HGC model, and contextualizes it in the light of recent advances in our understanding of the evolution of human life histories and against the background of basic Catarrhine adaptations for infant and juvenile care and development. While child care is highly facultative in the range beyond hunting and gathering, variation is more limited in these cultures, which in some ways represent our environments of evolutionary adaptedness (EEAs), and which probably help explain the success of our species. While there is limited evidence for negative consequences of departures from this pattern (compared, for example, to the consequences of mismatch in diet), there may still be lessons to be learned from the HGC model.

Americana Salon 3 Saturday, July 20, 9:00AM The evolutionary biology of education: Children’s educative instincts can work well today Peter Gray, Research Professor, Department of Psychology, Boston College Education is broadly defined as the set of processes by which each generation of human beings acquires the culture in which they grow up. By this definition, education is part and parcel of our biological makeup, as we are the supremely cultural animal. An analysis of education in hunter-gatherer bands helps us understand how young humans naturally and joyfully educate themselves through their self-directed play and exploration. Research at a modern-day democratic school designed to facilitate self-education demonstrates that our hunter-gatherer educative instincts are fully adequate for education today, given appropriate environmental conditions. In this talk I’ll describe the human educative instincts and the conditions that optimize their operation in today’s world—conditions that are quite opposite to those of our standard schools.

Americana Salon 3 Saturday, July 20, 2:00PM What game theory applied to cleaning mutualism may tell us about links between cooperation and cognition Redouan Bshary, Institut de biologie, Université de Neuchâtel There is very little doubt that humans are more able to cooperate with unrelated partners than any other species. Evolutionary explanations for our cooperativeness focus on strong between-group competition and on our advanced cognitive abilities, including theory of mind, empathy, or moral. A standard tool to study human cooperation is to test the predictions of game theoretic models. Interestingly, these models do not make any explicit assumptions about cognitive processes that need to be present in order to achieve cooperative outcomes. I will present evidence that a variety of game theoretic concepts developed for humans like partner choice, punishment, social prestige and the ‘shadow of the future’ can be used to study marine cleaning mutualism. In addition, I will present some first insights about the cognitive processes underlying the cleaners’ sophisticated behaviours.

67 Talk Abstracts

WEDNESDAY, July 17

AFTERNOON SESSION

Americana Salon 1 Symposium: Misconceptions about human social evolution Organizer: Claire El Mouden 4:20 Public Goods Games do not provide evidence for pro-social preferences Max Burton-Chellew, Stu West (contact: [email protected]) It has become an accepted paradigm that humans have “prosocial preferences” that lead to higher levels of cooperation than those that would maximize their personal financial gain. However, the existence of prosocial preferences has been inferred post hoc from the results of economic games, rather than with direct experimental tests. Here, we test how behavior in a public-goods game is influenced by knowledge of the consequences of actions for other players. We found that (i) individuals cooperate at similar levels, even when they are not informed that their behavior benefits others; (ii) an increased awareness of how cooperation benefits others leads to a reduction, rather than an increase, in the level of cooperation; and (iii) cooperation can be either lower or higher than expected, depending on experimental design. Overall, these results contradict the suggested role of the prosocial preferences hypothesis and show how the complexity of human behavior can lead to misleading conclusions from controlled laboratory experiments.

4:40 Common misconceptions about the evolutionary explanations for behavior in economic games Claire El Mouden (contact: [email protected]) In the social sciences, it is widely accepted that standard evolutionary theory, such as inclusive fitness theory, cannot explain human social behaviours, because cooperation occurs in one-shot economic games. Therefore, it is widely accepted that novel evolutionary explanations are required, such as strong reciprocity, inequity aversion, or altruistic punishment, and that these may require group selection to evolve. I challenge this view and suggest that inclusive fitness theory can explain human sociality, without the need for uniquely human evolutionary explanations. I suggest a key reason for these theoretical disagreements stems from misconceptions about the explanatory role of evolutionary theory in experimental studies.

5:00 Kin and group selection describe the same process: natural selection Geoff Wild (contact: [email protected]) The Price Equation is considered by many to be the theoretical backbone of sociobiology. In this talk I will give a brief outline of the Price Equation, and I will present two of its equivalent decompositions. We will see that one decomposition corresponds to the multilevel-selection (group selection) view of evolution, while the second corresponds to the kin-selection (inclusive fitness) view. I will argue that the two viewpoints, though often touted as being in opposition, are equivalent in the sense that they make the same predictions as the Price Equation. Time permitting, I will also argue that the mathematical theory of branching processes also provides a theoretical framework within which sociobiology may be discussed. Like the Price Equation, branching process offer researchers the flexibility of studying a problem using their preferred interpretation.

5:20 You’d better not treat ME that way! Third party punishment may not be what you thought Max M. Krasnow, Andrew W. Delton, Leda Cosmides, John Tooby (contact: [email protected]) People sometimes punish third parties—that is, punish a bad actor despite not being the target of the actor’s bad behavior. This happens even in isolated interactions with anonymous others. On some views this empirical fact suggests a psychology designed to pay costs to punish violators of group norms, with these costs being recouped later in the group’s greater success in intergroup conflicts. Other perspectives view this behavior as the outcome of a psychology designed to use punishment to bargain for better treatment of the self and allies. Previous experiments have been poorly suited to disentangling these two theories. Minimally elaborating a standard third party punishment procedure, we find strong support for the latter view. We measured punishers’ estimates of the cooperative disposition of a bad actor toward both the punisher and toward the person harmed by the bad actor, both before and after the bad actor’s harmful action. As predicted by the punishment-as-bargaining theory, punishers view the harmful action as a cue to how the actor would treat the punisher, and this inference drives punishment of bad actors.

68 5:40 Punishment and the evolution of group cooperation in the absence of higher-order selection Andrew W. Delton, Max M. Krasnow, Leda Cosmides, John Tooby (contact: [email protected]) Humans cooperate in groups, including sizeable groups. Previous analyses suggested that individual-level selection has difficulty explaining group cooperation, especially as groups become large. This has motivated alternative accounts based variously on genetic or cultural group selection or gene-culture co-evolution. But these accounts often ignore key features of human sociality. We show, using simulations that include one ignored feature, namely that cooperation occurs in multiple, overlapping groups, expands the scope of individual selection to create cooperation. Agents cooperate in sequential, one-shot public goods games; after each game, groups are randomly reformed. Agents remember only those other agents who previously, directly punished them and use this to modulate their cooperation. Tendencies to cooperate and tendencies to punish are quantitative, independently evolving variables. This selective regime creates agents whose psychology and behavior qualitatively matches humans’: Agents are very willing to cooperate, moderately willing to punish, and cooperate in fairly large groups. These results obtain despite no possibility of higher-order selection.

Americana Salon 2 Symposium: Political decision-making Organizer: Casey Klofstad 4:20 Candidate voice pitch influences voters Casey Klofstad (contact: [email protected]) Recent research shows that men and women prefer to vote for male and female candidates with lower voices. They are perceived as stronger and more competent. These studies are based on hypothetical elections conducted with college undergraduates. It remains to be seen whether the influence of pitch is a more general phenomenon. This question is addressed with an experiment conducted with a large sample of American adults. I find that men and women prefer to vote for male candidates with lower pitched voices. Contrary to previous studies, however, neither men nor women distinguished between the pitch of female candidates’ voices. A second study examines the relationship between candidate pitch and electoral outcomes in the 2012 U.S. House of Representatives elections. The results show that candidates with lower voices were more successful. These findings show that political behavior cannot be understood in isolation from biological influences.

4:40 The behavioral immune system and anti-immigration attitudes: Individual differences related to disgust shape opposition to immigration Lene Aarøe, Michael Bang Petersen, Kevin Arceneaux (contact: [email protected]) Why does the issue of immigration ignite so strong political attitudes and why is peaceful integration between so difficult? We argue that this is so because immigrants activate biological, visceral mechanisms designed for disease avoidance that operate through one of the most powerful emotions – disgust – and are specifically designed to remain active even facing cues that would otherwise inspire peaceful co-existence. In cross-national surveys and experiments we demonstrate that disgust- sensitive individuals hold stronger anti-immigration attitudes and assign greater importance to factors indicative of the deep background of an individual when making in group/out group classifications. We show that the effects of disgust sensitivity endure in the face of cues that have proven to dampen opposition towards immigration in prior research but are unassociated with the behavioral immune system. Finally, we also demonstrate that worry about diseases predicts anti-immigration attitudes which more directly suggests that disease-avoidance is a key issue here.

5:00 Facial dominance predicts candidates’ political positions, candidates’ electoral success and parties’ nomination strategies Lasse Laustsen, Michael Bang Petersen, Israel Waismel-Manor (contact: [email protected]) Individuals’ physical features influence their behaviors and political positions on issues such as war and egalitarianism (Sell et al., 2009; Price et al., 2011). Replicating these findings on the elite level we show that even when controlling for candidates’ age, sex and ideological wing, facial dominance of Danish parliamentarian candidates correlates negatively with egalitarianism but positively with support for Danish presence in Afghanistan and stricter immigration policies. From this we further predict that facial dominance should be of particular benefit to rightwing candidates in relation to parties’ nominations and voters’ electoral decisions. These predictions are strongly supported with facial dominance being positively correlated with the electoral success of rightwing – but not leftwing – candidates in the 2009 local as well as the 2011 national elections in Denmark. Likewise, facial dominance is found to be significantly related to top ballot positions for rightwing – and not for leftwing – candidates.

69 5:20 Birth weight influences social and political orientations under current stress Michael Bang Petersen, Lene Aarøe (contact: [email protected]) We suggest that one distal cue that natural selection has prepared our minds to use when making predictions about social environments is the intrauterin flow of nutrients from mother to the self as indexed by the birth weight of the self. Given the importance of the mother’s social environment for the birth weight of the child, birth weight provides an indirect but hard-to- fake cue to the larger social environment in which the child will come to be situated in. Because negative social factors (i.e., lack of social support) predict low birth weight, we predict that low birth weight is utilized as a cue of harsher social environments and give rise to avoidant social strategies. We test this hypothesis in two studies. Consistent with our prediction – and controlling for potential confounds – we find that low birth weight increases social avoidance and correlates in the domain of politics (e.g., social conservatism).

5:40 Coalitional psychology and international politics Anthony Lopez (contact: [email protected]) The application of evolutionary psychology to the study of international politics faces two hurdles: overcoming skepticism regarding the ability of evolutionary models to explain and predict behavior in the social sciences, and bridging the methodological ‘gap’ between individual-level psychology and macro-level political behavior. Here I focus especially on the latter challenge, and I argue that research on human coalitional psychology offers opportunities for scaling this ‘gap’ toward a richer understanding of international politics. A particularly robust area for research at this methodological intersection is the study of war, or coalitional aggression. Given the ancestrally recurrent challenges of navigating hostile coalitional landscapes, selection likely favored a range of psychological adaptations for the regulation of behavior in war. I discuss research on coalitional aggression and its application to international politics with special emphasis on dynamics related to leadership, revenge, and deterrence.

Americana Salon 3 Symposium: The evolution of social cognitive development Organizer: Annie Wertz 4:20 Evolved social learning mechanisms for the botanical world Annie Wertz, Karen Wynn (contact: [email protected]) Plants have been central to human life as sources of food and raw materials for artifact construction across evolutionary time. But plants also have potentially dangerous chemical and physical defenses (such as noxious oils and thorns) that provide protection from herbivores. Across a series of studies, we present evidence that human infants possess learning systems that balance these costs and benefits. In the absence of social information from adults, 8- to 18-month-old infants exhibit a striking reluctance to reach out and touch plants compared to other types of entities—a strategy that would protect infants from hazardous plant defenses. However, this strategy can be selectively overturned by relevant social information, allowing infants to learn the useful nutritional, chemical, and physical properties of plant species in their local environment over the course of ontogeny. These results suggest the existence of content-specific social learning mechanisms in human infants.

4:40 Infants use of confidence and competence cues in social learning Vivian Lee, M.D. Rutherford (contact: [email protected]) Infants and children gain cultural knowledge primarily from observing and interacting with others. However, not all such information is relevant. Learning biases may have evolved to allow for the selective acquisition of appropriate information. Previous research has implicated a “confidence bias”: children are more likely to imitate individuals who display confidence. However, past research conflates confidence with competence (i.e. how accurate an individual is at carrying out a goal). The current study expands on these findings by disaggregating information provided by these cues. Forty-eight 16-month-olds watched a model as she demonstrated an action using tools while displaying high or low levels of confidence and/or competence. Results indicate that infants were significantly more likely to imitate individuals who are competent, and are influenced less by their confidence level. These findings suggest that selection may have shaped cognitive mechanisms that bias learning of culturally important information towards more functionally relevant cues.

70 5:00 Moral judgment and action in preverbal infants and toddlers: Evidence for a reliably developing moral core J. Kiley Hamlin (contact: [email protected]) Although traditionally studied from a learning and development perspective, evolutionary psychologists are increasingly exploring the possibility that morality evolved to sustain collective action and cooperation within groups of unrelated individuals. This talk will review evidence that infants and toddlers are intrinsically prosocial, morally evaluative, and morally retributive. In Study 1, toddlers were rated as happier (on a Likert scale) when engaging in personally-costly versus non-costly giving behavior, suggesting they derived emotional benefits from behaving prosocially. In Study 2, 8-10-month-olds privileged intention in their evaluations of those who helped and harmed third parties, in situations involving failed attempts, accidents, and ignorance. In Study 3, 5-month-olds positively evaluated others who punished antisocial individuals, and toddlers themselves punished those who failed to punish antisocial others appropriately. The presence of such mechanisms so early in life supports the claim that some of the emotional and cognitive systems supporting morality reflect core aspects of human nature.

5:20 Coalitional psychology on the playground: Reasoning about indirect social consequences in preschoolers and adults David Pietraszewski (contact: [email protected]) We examine a key element of coalitional psychology—how relationship information is used to anticipate how others will react to events in which they are not directly involved. This requires both using relationship information to modify expected reactions (e.g., friends may be more responsive than acquaintances) and also inference rules for restricting the class of reactions that may be felt or experienced on behalf of others (e.g., uninvolved friends may become angry but cannot become dizzy). These capacities were examined in both preschoolers and adults. For both sets of participants, cues to relationship status had a strong impact on anger expectations (uninvolved friends were expected to be more angry than uninvolved strangers), but had no effect dizziness expectations (neither uninvolved friends nor strangers were expected to be dizzy), suggesting that highly specialized inference engines are engaged upon exposure to coalitional cues, even in young preschoolers.

5:40 Specialized mechanisms for theory of mind: Are mental representations special because they are mental or because they are representations? Adam S. Cohen, Tamsin C. German (contact: [email protected]) Does theory of mind, the ability to predict and explain behavior in terms of mental states, depend on evolved specializations for computing representations in general or mental representations? Previous tests have been unable to adjudicate between these two theories because of various problems matching tasks involving mental and non-mental representations. To address these problems, belief reasoning was compared to reasoning about linguistic representations. In a series of experiments with both children and adults, there was a sizable reaction time advantage to process mental (belief) over linguistic (written note) representations when representational content was emphasized alone and when representational content and medium were emphasized together, a manipulation that should have favored activation of representation concepts, yielding similar – not different, as observed – reaction times. These results support the theory that the underlying evolved mechanisms are a) specialized for computing mental states and b) early and reliably developing.

Americana Salon 4 Symposium: Current directions in the evolutionary study of humor and laughter Organizer: Thomas Flamson 4:20 Encryption and individual differences in sense of humor Thomas Flamson, Clark Barrett (contact: [email protected]) The encryption theory of humor (Flamson and Barrett 2008) hypothesizes that humor functions as an honest signal of personal features that allows individuals to assess their similarity with other members of the local group in terms of a variety of locally variable features. People with different knowledge, personalities, attitudes, values, or experiences should demonstrate differences in their sense of humor. Rather than treat it as a qualitatively variable trait, where some have a “good” sense of humor and some have a “bad” one, this model treats humor as an index of individually varying features, and expects widespread variation in humor preferences, styles, and products, reflecting the local variation it was designed to signal. This talk will review a wide array of prior studies on individual variation in sense of humor and how it relates to variation in these other features: personality, attitudes and values, and social group experiences. Further, evidence for the encryption theory’s hypothesis that compatibility in these features signaled by humor will relate to assortative behavior will be assessed.

71 4:40 Identifying in-group and self-deception: what both scientists and comedians have to say about the evolutionary function of humor and what is funny Robert Lynch (contact: [email protected]) My research has focused on the effect of both in-groups and self-deception on humor appreciation. I provide some evidence that people who share your beliefs and preferences laugh more at your jokes and find you funnier, and those who score high on a self-deception questionnaire seem to have an impaired sense of humor. Lately, however, I have been performing stand-up comedy in New York City and would also like to share some less scientific observations about what I, and other comedians, say and think is funny. I am currently exploring, and writing a book, on the evolutionary function of humor from the perspective of both scientists, who have studied the issue, and comedians who make their livings making people laugh.

5:00 Humor as a mental fitness indicator: Different jokes for different goals Christopher Wilbur (contact: [email protected]) Humor is a complex, multifaceted construct that serves numerous functions, including ostracism, coping with adversity, and mate selection. I propose that evolutionary pressures have fashioned in men a propensity to advertise their mate quality, and that humor production is one means of doing so. Because humor production requires cognitive skill and varies enormously in its content, it is a fitness indicator that can reliably indicate numerous possible qualities, including intelligence, warmth, and social dominance, which are differentially important across different mating contexts. I present data suggesting that men advertise mate quality through the production of humor and that women carefully evaluate these humorous offerings, inferring underlying traits in doing so, in service of judicious mate selection. Convincing evidence that humor production advertises specific qualities will come from research showing that specific forms of humor are differentially evaluated by women, depending on their mating goals.

5:20 Gender differences in the effects of relationship satisfaction and self-perceived physical attractiveness on humor ability in long-term relationships Melanie Beaussart, Scott Kaufman, James Kaufman (contact: [email protected]) There is a large body of work that has focused on the interpersonal effects of humor within the sphere of courtship behaviors. Humor production serves to function in ways that enhance relationship satisfaction, although it is possible that humor’s efficacy is dependent on the attractiveness of the person wielding it. Furthermore, these effects could be different between the sexes. In this study, participants were asked to write humorous captions and then complete a series of measures that evaluated their self-perceived physical attractiveness, duration of their longest relationship, and their general relationship satisfaction. These results support the idea that even though men with increased humor ability reported greater relationship satisfaction, only women and not men who fell into the lowest levels of self-perceived physical attractiveness scale were able to benefit significantly from having high humor ability in terms of an increased duration of their romantic relationships. These findings are discussed using the theoretical framework of evolutionary psychology, specifically mate-retention tactics.

5:40 Humor quality, attractiveness, and person perception Eric Bressler, Sigal Balshine (contact: [email protected]) Prior research has found that men’s use of humor enhances their desirability to women. This supports the notion that the evolution of humor has been influenced by sexual selection, suggesting that producing humor may signal quality (either genetic or parental) while evaluating and appreciating humor may enhance acquisition of resources from partners. However, not all humor is equally funny. If humor signals quality, then individuals who persistently produce bad humor may reduce their own desirability compared to those who do not try to be funny. Here, we present preliminary results investigating how humor of varying quality influences desirability. Our results support the notion that humor quality is positively related to the influence it has on the desirability of the humorist, and hence humor production may have evolved as a risky courtship strategy.

72 Poinciana 3/4 Culture I: Kinship and social learning 4:20 Kinship cues and demographic transition: The evolutionary origin of mass ideologies Tamas David-Barrett, Robin Dunbar (contact: [email protected]) What is the effect of changing fertility on the ability of a society structured by kin to generate social action. We use an agent- based model with two sexes, inherited resources, assortative pair formation, and bilateral accounting of relatedness to address this question. We show that (1) lower fertility reduces social inequality. We also show that (2) if collective action is organised along relatedness, the efficiency of social action collapses with reduced fertility, and so does the maximum size of an effective group. We thus suggest that societies that did not collapse after a decline in fertility solved this problem via the emergence of mass ideologies that facilitate collective action using kin cues. We also show that (3) the optimal relatedness accounting depth is three generations for societies in traditional fertility levels, but loses importance as fertility rate falls. Our work offers a new insight into the relationship between inherited kin-cue sensitivities of evolutionary origin and macro societal phenomena of cultural origin.

4:40 An East-West comparison of learning strategies: Do Chinese and British participants show equally sub-optimally low rates of social learning? Alex Mesoudi, Keelin Murray, Lei Chang (contact: [email protected]) Recent cultural evolution research has examined the evolutionary basis of social/individual learning, asking when and why it is adaptive to copy others versus rely on one’s own individual learning. While models have identified a range of conditions under which social learning is adaptive, lab experiments have found that people copy others less than expected. For example, Mesoudi (2011,EHB) had participants design arrowheads via individual or social learning; only a minority of participants copied successful demonstrators, even though copying yielded higher monetary payoffs. One explanation for this finding is that participants in such studies are from Western (or WEIRD) countries, and individualist Western values over-emphasise individual learning. Consequently, we re-ran the arrowhead task with Chinese students in the UK, who are significantly less individualist. There were no significant differences in rates of social learning between Chinese students and their UK counterparts, and learning strategy was unrelated to individualism/collectivism. This suggests that sub-optimally low rates of social learning in experiments are not due to the cultural background of the participants.

5:00 Information sharing strategies: What drives the transmission of information? Maxime Derex, Bernard Godelle, Michel Raymond (contact: [email protected]) The use of social information is a prerequisite to the evolution of culture. In humans, social learning allows to aggregate adaptive information and to raise the complexity of technology at a level unparalleled in the animal kingdom. However the possibility to use social information is related to the availability of this type of information. Although most cultural evolution experiments assume that social learners are free to use social information, there are many examples, particularly from ethnographic studies, of information withholding. To identify the factors that underlie the sharing of information, we constructed an experiment in which players were faced with a complex virtual task and had the possibility to trade information within their own group. The dynamics of the information transmission was studied both when competition was within or between groups. It was found that the between-group competition increased the transmission of information within the groups. Additionally we show that the flow of information varied according to several factors, including type of competition, type of information and quality of the information.

5:20 Social learning in the cooperative domain Shakti Lamba (contact: [email protected]) Cultural group selection models posit that large-scale cooperation evolves via selection acting on populations amongst which behavioural variation is maintained by the cultural transmission of cooperative norms. These models assume that individuals acquire cooperative strategies via social learning. However, this core assumption remains empirically untested. I test this assumption by investigating whether individuals employ pay-off biased, conformist and/or individual learning when making decisions in public goods games conducted in 14 villages of a small-scale forager society, the Pahari Korwa of India. I find that while a minority of individuals did employ social learning, the frequencies of different learning strategies are highly variable across populations. This variation is partly explained by demographic differences between populations, most notably population size. The results suggest that whether or not individuals use social learning in the cooperative domain, and the extent to which they do so, is contingent on their circumstances and the environment that they live in. These findings question the existence of stably transmitted cultural norms of cooperation.

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Americana Salon 1 Signaling I 10:20 Preferences for vocal masculinity in male and female leaders are context-dependent Cara Tigue, Paul J. Fraccaro, Jillian O’Connor, Katarzyna Pisanski, David Feinberg (contact: [email protected]) Voice pitch, the primary vocal cue to attractiveness and dominance, influences voting preferences. Cues to vocal tract length, a correlate of height, also influence perceptions of dominance. Prior work has found that voters preferred to vote for men and women with lower-pitched voices. Additionally, voters were more sensitive to low pitch during wartime than peacetime, suggesting that preferences for leaders are context-dependent. We investigated the influence of voice pitch and vocal tract length on voters’ perceptions of leaders in different contexts. We found that participants preferred to vote for higher-pitched women’s voices. Participants also preferred to vote for leaders who sounded taller, but this preference was only consistent in women’s voices regardless of pitch. Lastly, participants associated low pitch in men’s and women’s voices with a greater likelihood of using military force and associated high pitch in women’s voices with a greater likelihood of admitting immigrants, preferences consistent with a parasite stress theory of the evolution of political values. Our results suggest that preferences for vocal masculinity in leaders are context-dependent.

10:40 Low-pitched male voices elicit anger from men: Evidence for the retaliation-cost hypothesis of aggressive intention signaling in humans Jinguang Zhang, Scott Reid (contact: [email protected]) Men who speak with relatively low voice pitch (measured as fundamental frequency, F0) are perceived to be more physically dominant than men who speak with higher pitch. But what maintains the honesty of this putative dominance signal? According to Enquist’s retaliation-cost hypothesis, a more intense signal (e.g., a low-pitched voice) is more likely to elicit aggressive responses from signal receivers, and this risk of being retaliated against ensures that only more motivated or stronger signalers can afford to use more intense signals. In two experiments we exposed male participants to recordings of neutral content with lowered or raised male F0 after inducing a competitive mindset in them with a sexual prime. As predicted, men's trait dominance positively predicted the number of aggressive words they generated (Experiment 1)—and physically stronger men were significantly quicker in identifying aggressive words in a lexical-decision task (Experiment 2)—in the low-F0 condition. Our research is perhaps the first to demonstrate men’s cognitive responses to male voice pitch as a dominance signal, and suggests that the retaliation cost helps maintain signal honesty.

11:00 A meta-analysis of voice and body size relationships Katarzyna Pisanski, Paul Fraccaro, Cara Tigue, Jillian O’Connor, Susanne Röder, Lisa DeBruine, Ben Jones, Bernhard Fink, Paul Andrews, David Feinberg (contact: [email protected]) Body size is a significant predictor of physiological, social, and reproductive outcomes. Although the human voice can convey an individual’s body size, four decades of research have produced mixed results regarding which vocal features reliably predict within-sex variation in size. We conducted a meta-analysis of numerous voice-size relationships for each sex. Analyses were based on a total of forty-six samples of adult vocalizers, obtained from seventeen published studies and five unpublished datasets, spanning fourteen countries. In general, relationships among voice features and height, but not weight, were stronger in men than in women. The strongest predictor of height was mean formant frequency among men (r¯ = -0.31, N = 250), and the fourth formant among women (r¯ = -0.25, N = 613). Fundamental frequency (voice pitch) only weakly predicted height among men (r¯ = -0.13, N = 1056) and women (r¯ = -0.07, N = 756). Funnel plots revealed no apparent publication biases. Our results confirm the source-filter theory prediction that formant frequencies, resonances of the supralaryngeal vocal-tract, relate to height among same-sex adults more reliably than does voice pitch.

74 Americana Salon 2 Aggression I 10:20 Is adolescent bullying an evolutionary adaptation? Anthony Volk, Joseph Camilleri, Andrew Dane, Zopito Marini (contact: [email protected]) Bullying appears to be ubiquitous across cultures, involving hundreds of millions of adolescents worldwide, and has potentially serious negative consequences for its participants (particularly victims).We challenge the traditionally held belief that bullying results from maladaptive development by reviewing psychological, biological and anthropological evidence that bullying may be, in part, an evolved, facultative, adaptive strategy that offers some benefits to its practitioners. In support of this view, we draw from research and data that suggests bullying serves to promote adolescent bullies’ evolutionarily-relevant somatic, sexual, and dominance goals, has a genetic basis, and is widespread among nonhuman animals. We identify and explain differences in the bullying behavior of the two sexes, as well as when and why bullying is adaptive and when it may not be. We offer commentary on both the failures and successes of current anti-bullying interventions from an evolutionary perspective and suggest future directions for both research and anti-bullying interventions.

10:40 Divide and conquer: When and why leaders create divisions between their subordinates Charlene Case, Jon Maner (contact: [email protected]) Evolutionary theories of dominance suggest that, although leaders are given power to help their groups achieve important goals, sometimes they are instead primarily motivated to protect their own power. One strategy used by alpha male chimpanzees to protect their power is preventing subordinates from forming coalitions. In 3 experiments, we demonstrated that human leaders use the same strategy. In each experiment, we randomly assigned some participants to the role of leader in a group interaction. We found that leaders (compared with non-leaders) reported heightened anxiety about group members socializing and potentially bonding with one another (Study1). Leaders also were more likely to limit the amount of communication allowed between group members (Study 2). Finally, leaders physically isolated subordinates to prevent them from interacting with one another (Study 3). Consistent with our theoretical framework, these effects were observed only among dominance-oriented leaders who felt their power could be threatened by subordinates.

11:00 Coalitional persecution of immigrants is motivated by dominance-boundary enforcement Lotte Thomsen, Siri Leknes (contact: [email protected]) Support for between-group hierarchy (Social Dominance Orientation, SDO) positively predicts ideological endorsement of assimilation as a prescribed acculturation strategy. Yet, in the very same samples, we found that SDO predicted support for coalitional persecution of immigrant outgroups (i.e. attacks on immigrant headquarters, and torturing and executing immigrant leaders) precisely when participants were primed with an assimilating immigrant, but not with one separating himself from the host culture. In another study, participants completed a persecution scale printed below iconic depictions of 1) between-group hierarchy (a pyramid with one color of circles on top and another on bottom), 2) communal sharing (both colors overlapping in a circle), or 3) a blank control. In three samples, persecution endorsement was highest when groups merged to one. In contrast, the dominance conditions did not differ from controls, suggesting that between-group dominance is the default that coalitional persecution is a motivated response to defend. Finally a double-blind administration of morphine, naltextrone, oxytocin, or placebo explored how the opioid and oxytocin systems fuel this response.

75 Americana Salon 3

Symposium: Evolutionary economics and decision-making Organizer: Vladas Griskevicius 10:20 Uncovering mechanisms for near-optimal exploration and exploitation in resource search Peter Todd, Ke Sang, Joaquin Goñi (contact: [email protected]) When searching for resources, organisms must adaptively trade-off between exploiting what they have found already and exploring for new undepleted sources. The optimal foraging strategy for patchy resources is to stay exploiting a patch until its rate of return falls below that of the environment as a whole, and then leave and explore for a new patch. Humans behave near optimal in such searches, both in external space (foraging and visual search) and also internally searching for concepts in memory. This suggests a common underlying search mechanism, but does not specify the forms that mechanism may take, which may be implemented as simple patch-leaving heuristics. Here we consider multiple sources of evidence, including models, temporal discounting experiments, and fMRI studies, to help elucidate the search mechanisms that can lead to near- optimal resource foraging.

10:40 From the bedroom to the budget deficit: Mate competition changes men’s attitudes toward economic redistribution Andrew White, Douglas Kenrick, Rebecca Neel, Steven Neuberg (contact: [email protected]) From a traditional economic perspective, attitudes toward resource redistribution should be related to one’s economic standing: Whereas individuals with fewer resources should favor redistribution, those with plentiful resources should not. Yet research finds that people often vote against their own economic self-interest. We propose that attitudes about resource distribution may reflect different mate competition strategies. Building on animal research showing that males to adopt cooperative versus competitive tactics depending on their competitive ability, we hypothesize that increased mate competition will lead men to adopt different attitudes to resource redistribution depending on their mate value. Using real-world voting data and lab experiments, we find that amplifying mate competition leads low mate-value males to become more cooperative and more favorable toward economic redistribution. By contrast, increased mate competition leads high mate-value males to become more individualistic and less favorable toward redistribution. These studies highlight how economic attitudes may reflect underlying mating strategies.

11:00 Spending on boys versus girls in economic recessions: Experimental evidence for the Trivers-Willard hypothesis Joseph Redden, Kristina Durante, Vladas Griskevicius, Andrew White (contact: [email protected]) According to the Trivers-Willard hypothesis, poor environmental conditions should lead parents to invest more in female rather than male offspring. Although many correlational studies have examined this hypothesis in humans, findings have been mixed. We use an experimental methodology to test whether investment in girls versus boys changes when people are made to feel wealthy versus poor. Across four experiments, experimentally inducing feelings of resource scarcity led people to consistently allocate more resources to girls relative to boys. When people were reminded about economic recessions, they bequeathed more assets to girls rather than boys in their will, and they increased willingness to pay for toys for girls versus boys. Additional studies revealed that economic conditions have the strongest effects on sex-specific resource investment as children near reproductive age. Taken together, these findings provide clear experimental evidence supporting the Trivers- Willard hypothesis in humans.

76 Americana Salon 4 Menstrual Cycle I 10:20 Women’s psychology of resource-based opposite-sex friendships Diana Fleischman, Carin Perilloux, David Buss (contact: [email protected]) The desire for resources has emerged as a consistent component of women’s mate preferences. However, the specific dynamics of opposite sex friendships involving resources have not been explored. This study is the first to examine the prevalence, personality factors and menstrual correlates of such friendships. Young women (N = 352) were asked about men in their lives who bought them gifts or meals but who were not romantic partners or kin. Of the women surveyed, 26% reported having such an opposite sex resource friend (RF). These women scored significantly higher on a dispositional measure of short-term sexual strategy than women without a RF, regardless of whether or not they had previously had sex with the RF. Women reported significantly lower levels of sexual and romantic interest in their RF than they believed their RF felt towards them. Finally, when at high fertility in the menstrual cycle, women were much less likely to have seen their RF in the last 24 hours if he tended to make frequent sexual advances towards her. Discussion focuses on limitations of this study and on implications of its novel findings.

10:40 Do hormonal contraceptives alter women’s mate choice and relationship functioning? Hypothesized mechanisms of action Christina Larson, Martie Haselton (contact: [email protected]) The vast majority of women in the Unites States have used hormonal contraceptives (HCs) at some point in their lives, and HCs are the most commonly used prescription medicine among women ages 18-44. Although an abundance of research has examined the physical health effects of HCs, we know virtually nothing about their psychological effects. Some evolutionary scientists have argued that HCs may alter women’s mate choice and relationship functioning (e.g. Alvergne & Lummaa, 2010). Given the accumulating evidence associating reproductive hormones and women’s social and sexual behaviors, this is a plausible idea. However, the evidence speaking to this issue is mixed, and the mechanism through which HCs might have effects remain unspecified. We propose three physiological mechanisms through which HCs might have psychological effects. We then review pertinent studies and discuss which hypotheses they support or do not support and which hypotheses remain untested. Finally, we outline suggestions for how future research can best address this important question.

11:00 Hormonal predictors of women's sexual motivation James Roney, Zachary Simmons (contact: [email protected]) Little research has directly addressed which hormonal signals may best predict cyclic changes in women’s mating psychology. To investigate hormonal predictors of women’s sexual motivation, we collected daily saliva samples across 1-2 menstrual cycles from a sample of young women; assayed samples for estradiol, progesterone, and testosterone; and also collected daily diary reports of women’s sexual behavior and subjective sexual desire. We found evidence for positive effects of estradiol and negative effects of progesterone on within-cycle fluctuations in subjective sexual desire. Desire exhibited a mid-cycle peak, and progesterone concentrations statistically mediated the fall in desire from mid-cycle to the luteal phase. Hormonal predictors of sexual behavior generally reached only trend levels of significance, though patterns were similar to those for desire. Our findings suggest homologies with nonhuman primates for which evidence likewise supports excitatory and inhibitory effects of estradiol and progesterone, respectively, on measures of female sexual motivation.

77 Poinciana 3/4 Cooperation I 10:20 Social networks of the Ifugao rice farmers Charan Chaudhary, Andrea Migliano (contact: [email protected]) There has been a growing interest in cooperative cluster formation as a mechanism that facilitates the evolution of cooperation. Band-wide sharing obligations and the mobile nature of foraging groups makes this mechanism particulary relevant to hunter-gatherers, as demonstrated by Apicella et al. 2012. In this research, I investigated whether cooperative clusters existed amongst the people of Wangwang, a subpopulation of the Ifugao rice farmers from the Philippines. The main aim was to understand whether the lack of mobility in an agricultural context would inhibit the formation of cooperative clusters. The results indicate that selective assortment does not occur i.e. individuals are not more likely to interact with those who are equally as cooperative as themselves. This is due to a combination of the costly nature of geographically distant ties and the lack of mobility; meaning individuals are not able to continuously adjust their social networks based on how cooperatively others behave. Instead, they build their homes next to their kin, where inclusive fitness benefits are guaranteed.

10:40 A new perspective on the evolution of human cooperation Emily Wyman (contact: [email protected]) The traditional paradigm for investigating human cooperation is the ‘social dilemma’. This is a game theoretic model that examines how collective action can stablize, when threatened by the profitability of individuals’ selfish actions. Another model, however, known as the ‘coordination problem’, focuses on how collective action can emerge when it is advantageous to all, but requires the coordination of actions and intentions towards some cooperative outcome. A series of studies will be summarized that investigate the behavior of both children and our closest living relatives, chimpanzees, in coordination problems. Main results will point to striking similarities, as well as species-divergence, in evolved coordination strategies. The social-cognitive mechanisms utilized by children to solve coordination problems will then be explored in more detail with reference, for example, to ‘Theory of Mind’ and different types of communication. Lastly, the implications of these findings for the evolution of human cooperation will be discussed.

11:00 Testing theories about ethnic markers: Ingroup dialect facilitates coordination, not cooperation Niels Holm Jensen, Michael Bang Petersen, Henrik Høgh-Olesen, Michael Ejstrup (contact: [email protected]) In recent years, evolutionary psychologists and anthropologists have debated whether ethnic markers evolved to solve adaptive problems related to interpersonal coordination or to interpersonal cooperation. In the present study we add to this debate by exploring how individuals living in a modern society utilize dialect of unfamiliar individuals to make social decisions in hypothetical bargaining games measuring interpersonal trust, generosity, and coordination. 4,603 danish participants completed a verbal-guise experiment administered over the internet. Participants listened to four speakers (two local and two non-local) and played a hypothetical dictator game, trust game, and coordination game with each of them. The results showed that participants had greater faith in coordination success with local speakers than with non-local speakers. The coordination effect was strong for individuals living in the same city as the particular speakers and weakened as geographical distance to the speakers grew. Conversely, the results showed that participants were not more generous toward local speakers and not more trusting of local speakers compared to non-local speakers.

78 Thursday, July 18

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Americana Salon 1 Signaling II 11:30 Costly signals and cooperation in structured interaction Károly Takács, András Németh (contact: [email protected]) Cooperative intentions can often be signaled at a lower cost by “true” cooperators than by defectors. This, however, does not guarantee the emergence of cooperation if individuals meet randomly. In structured populations, signaling might also be important, as cooperative intentions cannot be learnt for all possible interaction partners. Our analytical results demonstrate that in the one-shot Prisoner’s Dilemma (PD) with symmetric pre-play signaling and spatially structured interaction, signaling and cooperation that is conditional on the signal received can prevail. We tested our theoretical predictions in laboratory experiments with human subjects. We first categorized subjects as “cooperators” and “defectors” based on their play in the one-shot PD. Then we introduced signals at a cost that was either differentiated or not for cooperators and defectors. We report how this affected play in the PD with random reshuffling and with structured interaction. There was a significant difference in signaling activity of cooperators and defectors only in structured interaction. We found that individuals are willing to pay for receiving signals in all experimental conditions.

11:50 Until death don't us part: Grief as a hard-to-fake signal of commitment Bo Winegard, Tania Reynolds (contact: [email protected]) From an evolutionary point of view, grief appears an inexplicably costly and wasteful process. The deceased that one grieves for cannot repay one's devotion. Using the frameworks of social selection and signaling theory, we propose that grief is a socially selected hard-to-fake signal of one’s current commitment to a group and of one’s capacity to form strong, non- calculated bonds with other people. Results from three studies show that those who grieve more intensely are rated as more trustworthy, more desirable, and more loyal than those who grieve less intensely. Furthermore, our results show that those who grieve more intensely than others are more likely to be chosen as partners in trust games and more likely to be cooperated with in a prisoner’s dilemma task. This suggests that perceivers distinguish between people based on their grief responses and preferentially select strong grievers as social partners.

12:10 TBD

79 Americana Salon 2

Aggression II 11:30 Are men more aggressive when mates are plentiful or scarce? A natural experiment in the outer islands of Yap Emily A. Stone (contact: [email protected]) Cross-cultural research on the effects of imbalanced sex ratios consistently finds a counter-intuitive pattern of aggression--men commit more homicides and assaults, or male contest competition over mates, when competition is expected to be the least intense (when women outnumber men, and mates are plentiful), compared to when men outnumber women and competition is expected to intensify. This study tests two hypotheses to explain this: a men’s mating opportunities hypothesis, which follows the adage that men are as faithful as their options, and so are competing more when women outnumber them because there are more mating opportunities to go around; and female choice, which predicts that men are less violent when women are scarce because women have bargaining power in this context and don’t find aggression appealing in a mate. I tested these hypotheses using observations and interviews on two outer islands of Yap, in the Federated States of Micronesia--an island in Ulithi atoll, where men outnumber women, and an island in Woleai atoll, where women outnumber men. Analyses are ongoing.

11:50 Adult male scarcity predicts adolescent violence at the neighborhood level Daniel Kruger, Sophie Aiyer, Marc Zimmerman (contact: [email protected]) The relative proportions of potentially reproductive males and females in a population influence a range of fitness relevant behaviors. Scarce females are more effective at securing male commitment and higher levels of resource investment. Male scarcity enhances mating opportunities and diminishes incentives for long-term commitment and investment. Male scarcity is associated with higher divorce rates, more out-of-wedlock births, more single mother households, higher rates of teenage pregnancies, and lower paternal investment. We hypothesized that adult male scarcity would predict the local rate of youth assaults, even when considering other known socio-demographic risk factors. We found that adult (ages 25-64) male scarcity and the proportion with less than a high school degree were the two unique predictors of Census Tract level youth assault rates (ages 10-24). These predictors explained 69% of the variance in youth assault rates in a Midwestern American city known for very high incidence of violent crimes.

12:10 Too many men: The violence problem? Ryan Schacht, Kristin Rauch, Monique Borgerhoff Mulder (contact: [email protected]) Recent high-profile cases of violence against women, such as the notorious 2012 Delhi gang rape case, have the public, journalists and researchers alike all searching for explanations. Both the popular and evolutionary informed argument center on male-biased sex ratios leading to higher levels of violence, mediated by higher intensities of selection (Is) among males at high adult sex ratios (ASR). While this reasoning is intuitive, we question both its underlying theoretical basis and its empirical support. First we highlight recent reformulations within sexual selection theory that challenge our intuitions and generate very different predictions regarding the mating market and patterns of competition. Second we tabulate existing literature on how violence is patterned with respect to ASR, and find very mixed results. Finally we present a comparative study across 18 populations which shows how higher (Is) are associated with lower ASRs, contrary to the arguments used by the public, journalists and scientists alike.

80 Americana Salon 3 Mating I 11:30 Casual sexual relations: Illuminating sexually dimorphic motivations and emotional reactions John Marshall Townsend (contact: [email protected]) Evolutionary theory proposes that sexually dimorphic mental mechanisms motivate the sexes to pursue different reproductive strategies. Ostensibly identical behavior can mask radically dimorphic motivations. These sexually dimorphic motivations are difficult to elicit with conventional measures because they often operate unconsciously and are socially unacceptable. Experiments and oral interviews can illuminate otherwise obscured sex differences in the following: (1) Thresholds of initial acceptance (i.e., the first cut). (2) Tradeoffs: Extremely high male status can override even caste-like traits, e.g., African- American athletes' hookups with white female fans. (3) Changes of mate preferences over time. (4) Emotional reactions to low- investment copulations. (5) Goals: Female college students engage in low-investment copulations for access to high-status environments/partners and for recreational chemicals; to assess and confirm their own mate value; to hone flirting and sexual techniques (e.g., fellatio) in order to attract and hold high-status males.

11:50 Sexual misperception among Norwegian students Mons Bendixen (contact: [email protected]) Error management theory (Haselton & Buss, 2000) maintains that the sex difference in misperception of sexual interest follows adaptively biased systems. Two forms of misperception have been identified: (1) Women more than men report sexual overperception committed by the opposite-sex (false-positive errors) and (2) men more than women report sexual underperception (false-negative errors). Sexual overperception by men has been found in studies using diverse methods, but underperception has barely been studied. This study of 181 female and 128 male Norwegian students is the first to apply Haselton’s (2003) methodology and in a non-US culture. Results: (1) women reported significantly more experiences of members of the opposite-sex inferring friendliness as sexual interest than did men, and (2) men reported significantly more experiences of the opposite-sex inferring sexual interest as friendliness than did women. The total number of misperceptions did not differ between sexes. Number of misperceptions was negatively related to age and long-term mate value, and positively related to sociosexuality. Findings are largely comparable to Haselton’s and in strong support of EMT.

12:10 Sexual misperception revisited: Evidence that men are accurate Carin Perilloux, Robert Kurzban (contact: [email protected]) Numerous studies have shown that men and women disagree about the meanings of flirtatious acts, with men routinely reporting women’s behaviors as more sexually suggestive than women report their behaviors to be. In a series of studies, we call into question the traditional interpretation of these data. The results of one set of studies indicates that even when men are paid to be accurate, they consistently infer more sexual interest from women than women report they intend. In a second study, women, when asked what other women intend by the same flirtatious behaviors, increase their ratings to match men’s. These results imply that the reason men report women’s behaviors as more sexually suggestive than women report their own behaviors to be lies not in men’s optimism, but rather in women’s under-reporting of their true sexual intentions. Implications for Error Management Theory are discussed.

81 Americana Salon 4 Menstrual Cycle II 11:30 Oral contraceptive use and the motivational salience of infant facial cuteness Amanda Hahn, Claire Fisher, Lisa DeBruine, Reiner Sprengelmeyer, David Perrett, Ben Jones (contact: [email protected]) Studies of perceptual judgments of infant faces suggest that women using oral contraceptives are more sensitive to cute infant facial characteristics than are women with natural menstrual cycles (Sprengelmeyer et al., 2009 Psychological Science). These results may implicate sex hormones in the regulation of responses to infant facial cues. It is not known if this link between oral contraceptive use and cuteness sensitivity is also evident in measures of the motivational salience of infant cuteness. Using an established measure of motivational salience, we show that (1) women will expend more effort to view cuter infant faces and (2) this effect of cuteness on motivation is greater among oral contraceptive users than it is among women with natural menstrual cycles. Importantly, this latter finding was not an artifact of the possible effects of partnership status and maternal desire. These findings are consistent with the proposal that sex hormones may influence motivation to engage with cute infants, which may function to optimize the allocation of maternal resources and attachment behaviors in new mothers.

11:50 Physiological changes in response to hearing female voices recorded at high and low fertility Melanie Shoup-Knox, R. Nathan Pipitone (contact: [email protected]) Circulating hormones across the menstrual cycle affect female vocal production. Previous research has shown differences in attractiveness ratings of voices as a function of the speaker’s fertility status. Conceivably, males who prefer female voices during high fertility times will experience both an inter- and intra-partner reproductive advantage. Few have investigated the proximate mechanisms underlying the preference for fertile female voices. The current study examines participant physiology (e.g., heart rate, skin conductance, skin temperature) while listening to fertile and non-fertile voice samples. Morphological characteristics (such as SHR & WHR) and Mating Intelligence scores were also collected. It is hypothesized that fertile female voices may elicit sympathetic nervous system activity resulting in changes in physiological measures among listeners. Further, we predict that the magnitude of these changes will be positively correlated with ratings of attractiveness for fertile voices, as well as fitness and mating intelligence indices among listeners.

12:10 Men perceive their female partners, and themselves, as more attractive around ovulation Kelly D. Cobey, Abraham Buunk, Thomas Pollet, Christine Klipping, S. Craig Roberts (contact: [email protected]) Accumulating evidence from controlled lab studies shows that women are perceived as more attractive near to ovulation; however, little research assessing the real world implications of such findings exists. In a sample of romantic couples we tested male perceptions of their female partner’s attractiveness across her menstrual cycle. We further examined how male self- perception varies in relation to partner conception risk. Finally, since use of hormonal contraception (HC) eliminates hormonal fluctuation, we examined these same topics after participants had transitioned onto ‘the pill’. This study benefited from the use of transvaginal ultrasonography to detect fertility during the regular cycle and the use of a within-subjects design. We found that men rate their partner as more attractive near to ovulation as compared to during the luteal phase or during use of HC. Moreover, our results point to a presently unrecognized negative consequence of HC on male self-perception, with men rating themselves lower in attractiveness when their partner is using HC than when she is regularly cycling.Results will be discussed in terms of their impact on within-couple social dynamics.

82 Poinciana 3/4 Cooperation II 11:30 Facial traits influence proposer behaviour in cross-cultural ultimatum games Poppy Mulvaney, Ian Penton-Voak (contact: [email protected]) Considerable research has explored individual differences in proposer behaviour in the ultimatum game, little has investigated the effects of receiver traits on offers. In study 1, 42 participants played the proposer in a series of virtual ultimatum games. They were presented with facial images of the male receivers in which masculinity had been manipulated. In study 2, 72 UK participants played a similar game against virtual opponents represented by unmanipulated male facial images and assessed each image for ‘trustworthiness’ and ‘formidability’ Study 3 and 4 replicated study 2 (N=157) in an American population. UK proposers made more fair offers to masculine than feminine faced receivers in study 1. In study 2, rated ‘formidability’ was a strong predictor of fair offers made; rated ‘trustworthiness’ had no effect. In study 3, in contrast to the UK population, ‘trustworthiness’ was associated with fair offers, and was a stronger predictor of behaviour than ‘formidability’. These data demonstrate that facial appearance of receivers influences proposer behaviour and the role of these attributions in economic decision making varies cross-culturally.

11:50 High fitness features influence cooperative behavior in woman not only through their attractiveness Enrique Turiegano, Jose Antonio Muñoz-Reyes, Pita Miguel, María Arjona, Santiago Sanchez-Pages (contact: [email protected]) Attractiveness is a feature with an important role both from a social and an evolutionary perspective. The present work analyzes to what extent attractiveness-related variables affect cooperative behavior in women. Cooperativeness in participants is evaluated through a Prisoner’s Dilemma Game (PDG). Several morphometric variables related to attractiveness were measured in the participants. Fluctuating Asymmetry (FA) the Waist-Hip Ratio (WHP), the Body Mass Index (BMI) and Facial Femininity (FF). We also measured the participants’ evaluation of their own attractiveness (Self-Perceived Attractiveness; SPA). We tested differences in these variables according to the behavior displayed in PDG. Beyond their relation with attractiveness, effects on human behavior have been described for all these variables. These effects are independent of the SPA, probing that the effect of attractiveness does not depend on participants´ awareness of their appeal, and that occurs regardless of their self-perception.

12:10 Prestige and punishment: Only dominant individuals can enforce a ‘credible threat’ of third party punishment David S. Gordon, Stephen Lea, Joah Madden (contact: [email protected]) Engaging in third party punishment raises one’s reputation, yet outside the laboratory instances of informal/spontaneous punishment are relatively rare. 108 participants were presented with a vignette describing an attempt at third party intervention by a group member. This member was described as either high or low status and attempted the punishment either by threatening violence or social ostracism. Participants reported how credible the threat was and their attitude to the punisher. Participants believed that only intervention by the high status member would be successful regardless of the type of punishment, and that High Status punishers were at less risk from retaliation. They liked punishers more when punishment was non-violent. Thus only dominant individuals were seen as able to enforce a credible threat of punishment and to do so without resorting to reputation-diminishing violent action. This suggests that social dominance may play an important role in the perceptions and expectations made of punishers, and thus may affect any benefits potentially gained from punishing

83 Thursday, July 18

EARLY AFTERNOON SESSION

Americana Salon 1 Cooperation III 3:20 Two types of within-group competition affect cooperation in social groups Jessica Barker, Pat Barclay, Kern Reeve (contact: [email protected]) Individuals in social groups may cooperate with others to produce shared group resources, or may individually produce private resources. Both types of resources are generally assumed to be non-monopolizable, and cases where within-group competition is possible have largely been overlooked. We used game theoretic models and laboratory economic games to investigate the effects of relaxing this assumption. We found that when people had the opportunity to compete over private resources (by investing in taking others’ resources and defending one’s own resources against others), they cooperatively contributed more to shared group resources. In contrast, when competition over the shared group resource was an option (by investing in taking more than an equal share), people cooperatively contributed less. These results shed light on how cooperative production and equal division of shared resources may have evolved, suggest how a tragedy of the commons may be avoided, and expand on current models of human cooperation to reflect the many opportunities for within-group competition.

3:40 The joint emergence of costly between-group conflict and within-group cooperation Mikael Puurtinen, Tapio Mappes (contact: [email protected]) Humans exhibit exceptional degree of cooperation between individuals but also unparalleled levels of violent between-group hostilities. It has been suggested that violent between-group conflict and costly within-group cooperation have evolved in tandem, with resources gained from conquered groups favoring group conflict and hostile conflict selecting for increased within-group cooperation. Here we show that groups of randomly assembled individuals spontaneously engage in costly hostile group conflict and maintain stable levels of costly within-group cooperation in a game played for substantial monetary rewards. The results underscore the intimate relationship between group rivalry and within-group cooperation in human evolution and social psychology.

4:00 “Us vs. Them” or “Us vs. Nature”: Cooperation and manipulation in response to social and asocial group threats Pat Barclay, Stephen Benard (contact: [email protected]) Group membership provides direct and indirect benefits in many species. Because of these benefits, individuals have an individual vested interest in maintaining the well-being of their social groups and helping their groups to survive threats such as harsh conditions or intergroup competition. Correspondingly, many researchers have shown that human groups cooperate more when competing with other groups. However, outgroup threats should elicit stronger cooperation than asocial threats like harsh environments because: a) one’s loss involves a competitor’s gain, and b) a strong cooperative reaction now may deter future outgroup threats. We tested this prediction in a multi-round public goods game where groups faced periodic risks of failure (i.e. loss of all money) which could be overcome by sufficient cooperation. This threat of failure was framed as either a social threat (intergroup competition) or an asocial threat (harsh environment). Our results show that cooperation was higher in response to social threats than asocial threats. Also, participants were more willing to manipulate others’ perceptions of the asocial group threats than social group threats.

4:20 Being there: A brief visit to a low-trust neighbourhood rapidly evokes low trust Daniel Nettle, Gillian Pepper, Kari Britt Schroeder (contact: [email protected]) Recent evidence has shown that there are marked differences between populations in the attitudes underlying social behaviours, such as trust. However, there has been almost no research on the psychological processes that give rise to these differences. These may involve ‘evoked culture’ - the rapid activation of domain-specific evolved mechanisms that respond to particular environmental cues. Here, we randomly transported experimental volunteers to either a neighbourhood where the residents reported high social trust, or a low-trust neighbourhood, and had them deliver letters to houses for 45 minutes. Participants went to the low-trust neighbourhood reported significantly lower trust in people they meet for the first time than visitors to the high-trust neighbourhood. They also reported more paranoid thoughts. We discuss the potential contribution of evoked culture to population differences in social behaviour.

84 Americana Salon 2 Symposium: Validating self-report life history measures Organizer: Pedro Wolf 3:20 Sleep, physical activity, affect, and life history strategy: A multi-measure, multi-predictor study Pedro Wolf, Kirsten Clacey, Candice Edmunds (contact: [email protected]) Using accelerometer and self-report data this study assessed Life History (LH), Sleep Quality (SQ), and Physical Activity (PA). Theory predicts that slow LH individuals should invest in Somatic Effort (SE) and fast LH individuals should invest in Mating Effort (ME). Theoretically, PA and LH strategy should not correlate. On one hand, PA promotes health and is a type of SE, but on the other PA is a necessary component of successful ME, thus, predicting a full range of PA scores across the spectrum of LH strategies. If we consider SQ and these variables simultaneously, a nuanced LH theory prediction emerges. For slow LH individuals to have a consistent LH strategy, those with high PA should set aside time to sleep well. This prediction does not hold for a high PA and fast LH strategists. From this perspective, an active fast LH strategist should have no problem foregoing SQ in order to invest more into ME. Our analysis found the predicted interaction between life history strategy (Mini-K) and PA (accelerometer) when predicting SQ. SQ was composite score composed of a validated self-report measure, a diary self-report measure, and an accelorometer measure of SQ.

3:40 Comparing hypotheses of assortative mating Sally Olderback, Pedro Wolf, Aurelio José Figueredo (contact: [email protected]) Assortative mating is a widely occurring phenomenon that theoretically enhances evolutionary fitness for slow life history strategists. While differential positive assortative mating is documented in humans, the proximate mechanisms are not well understood. This presentation will focus specifically on hypotheses about the proximate mechanisms of assortative mating as well as individual difference traits as predictors of individual differences in the preference to assortatively mate or in trait perception ability. Hypotheses were tested in a half-block quasi-experimental design with the traits: Mate Value, General Factor of Personality, Life History Strategy, and Mating Effort. Results are mixed, but in general suggest there is assortative mating, and not active disassortative mating, on these traits. In addition, individuals seem most concerned with mate value because perceived or actual mate value, and perceived or actual similarity on mate value, were the most consistent predictors of interest in a stranger. There was mixed support that these individual difference traits predicted preference to assortatively mate or trait perception ability. Implications are discussed.

4:00 The behavioral correlates of overall and distinctive life history strategy Ryne Sherman, Aurelio José Figueredo, David Funder (contact: [email protected]) Psychometric assessment of life history is largely limited to self-reports. Using template matching, this paper examines the relationship between personality differences associated with slow-life history (slow-LH) and social behavior in three datasets. The first two include direct laboratory observations of behavior and the third provides self-reports of real-life behavior occurring 24 hours prior. The results are consistent with slow-LH individuals engaging in adaptive social behaviors. However, when “normativeness” (a tendency to be normal in both the statistical and evaluative sense) is statistically removed from the LH scores, a different picture emerges. Both slow- and fast-LH persons behave adaptively or maladaptively depending on context. Slow-LH individuals behaved in a manner that was considerate, hard-working, and reliable but socially awkward, insecure, and over-controlling. Fast-LH individuals were talkative, socially skilled, dominant, and charming but unpredictable, manipulative, and impulsive. These results are consistent with LH strategies being adapted to systematically different environments.

4:20 Life history status predicts the form and success of sexual strategies in college-age men and women Tarah Swanepoel, Pedro Wolf, Kevin Thomas (contact: [email protected]) Life History (LH) Theory predicts that males and females who emerge from different environmental contexts, and who consequently differ in their LH status, will differ in the form, number, and success of their mating displays and sexual strategies. We tested whether this prediction holds in short-term, anonymous online interactions by describing the behavior (i.e., the mating displays and sexual strategies) of men and women with slow and fast life histories who interacted in hour-long chatroom sessions. Statistical analyses indicated a remarkable correspondence between predictions derived from LH theory and the behavior of men and women in the chatroom (e.g., fast LH status men interacted with more women than slow LH status men did). Furthermore, women rated those men who behaved in a manner consistent with their measured LHS. These results confirm predictions that men and women with different LH status display different and specific patterns of mating displays in a short-term anonymous online environment, and that those patterns mirror the patterns LH Theory predicts they would exhibit in real-world social transactions.

85 Americana Salon 3 Morality and the law 3:20 Why humans (especially simple foragers) are so egalitarian Frank Marlowe (contact: [email protected]) Stratified human societies lack the physical threats of most primates, threats that help establish dominance hierarchies. The exceptions are perhaps kindergarteners and prison inmates. Using the Standard Cross-Cultural Sample of 186 societies, I first show that the 36 hunter-gatherer societies are less stratified than the horticulturalists, pastoralists, and agriculturalists. Next, I analyze the variation within those 36 hunter-gatherer societies. In the roughly half that we can call 'the warm-climate, simple hunter-gatherers', those probably most similar to our Pleistocene ancestors, there is the most egalitarianism. I analyze several variables that influence the degree of egalitarianism in foragers. The most important correlates of greater egalitarianism among foragers (p < .0005 in all) are: 1) lack of food storage, 2) greater mobility, 3) multi-local residence, 4) central place provisioning, 5) more big game hunting and 6) less fishing. Deadly weapons may be another important factor but this will be difficult to test.

3:40 Female economic dependence and the morality of promiscuity Michael Price, Nicholas Pound, Isabel Scott (contact: [email protected]) In theory, in environments characterized by greater female economic dependence (on male mates), both sexes should value paternity certainty more, and should thus be more opposed to promiscuity (because promiscuity undermines paternity certainty). We tested this theory in two studies involving U.S. participants (N = 656 and N = 4,533). In both studies, we tested whether anti-promiscuity sentiment was predicted by perceived levels of female economic dependence in the social environment. In study two we also tested whether economic indicators of female economic dependence (e.g. female income, availability of welfare benefits) predicted anti-promiscuity sentiment at the state level. Results indicated that as predicted, at the individual level, perceived female economic dependence was a positive predictor of anti-promiscuity sentiment, even after controlling for predictors such as age, sex, religiosity, political conservatism, and the anti-promiscuity views of one’s nearest geographical neighbours; and at the state level, median female income was a negative predictor of anti-promiscuity sentiment, in a relationship that was fully mediated by perceived female economic dependence.

4:00 People’s ownership intuitions about disputes between finders and landowners Peter DeScioli (contact: [email protected]) Humans use a variety of property conventions to resolve resource disputes and alternative rules of ownership can come into conflict. Here we investigate people’s judgments about classic property law cases involving disputes between the finder of an object and the landowner where the object was found. Participants read scenarios and judged whether an object belonged to the finder or landowner. The scenarios were variations of the original cases designed to test hypotheses drawn from the legal literature—the influence of location, whether the object was below or above ground, contracts between landowners and finders, and the distinction between public and private space. The results show that the nature of the location is critical: Landowners are assigned objects found in private spaces, and finders are assigned objects found in spaces accessible to the public. We discuss the implications of these results for understanding ownership intuitions and property institutions.

4:20 Relative morality: Influences of social relationship on moral decision making Meaghan Altman (contact: [email protected]) Evolutionary theory has been applied to social behaviors including altruism, cooperation, violence, and homicide. Data suggest that social behavior is contextualized by nepotistic motives. This project tested the hypothesis that moral behavior is also sensitive to these motives. This investigation employed variations of the Trolley, Footbridge, and Crying baby dilemmas to examine the effect of relationships on moral decision making. Participants (n = 203) were asked to make life-or-death choices involving siblings, offspring, friends, classmates, and strangers. Data on emotional closeness, familiarity, and similarity to targets was collected for covariate analyses accounting for proximate mediators of choice. Analyses supported the hypothesis: for example, participants were significantly more likely to make decisions that favor sibling survival in all dilemmas, and decisions to save friends and in-group members were conditional on dilemma type. Results are interpreted to support the broader hypothesis that moral behavior is mediated by contextual factors related to fitness.

86 Americana Salon 4 Kinship I 3:20 Genetically unrelated look-alike individuals: Novel tests of social closeness and personal similarity Nancy L. Segal, Jamie L. Graham, Ulrich Ettinger (contact: [email protected]) A novel “twin” design assessed associations between phenotypic matching and social attraction, based on evolutionary theorizing. The sample was a rare group of 23 unrelated look-alike pairs (U-LAs). Few U-LAs expressed the highest levels of initial and current closeness (17%, 21.4%) and familiarity (15.2%, 21.4%). Over time, the greatest average change in closeness was from somewhat close to not close, and somewhat familiar to not familiar. In contrast, higher proportions of MZ and DZ twins reared apart expressed the highest levels of closeness (MZA: 70%, 80%; DZA: 49%, 62%) and familiarity (MZA: 62%, 79%; DZA: 25%, 60%), upon meeting and subsequently, with levels increasing over time. U-LAs’ mean correlations across the Big Five personality traits were also assessed, using two different measures, and found to be -.05 and -.03, respectively. Phenotypic matching (in appearance) does not predict close relations between people in the absence of perceived behavioral similarities.

3:40 An expanded concept of kin recognition by phenotype matching Daniel Krupp, Peter Taylor (contact: [email protected]) Species across several kingdoms have evolved recognition systems designed to discriminate partners on the basis of genetic relatedness. Among humans and other animals, several of these kin recognition systems depend upon a phenomenon known as “phenotype matching,” historically described as a process whereby the evaluator compares information about its own phenotype with that of its partner. By building a simple quantitative genetics model of relatedness conditioned upon phenotypic information, we show here that this description is inadequate. In our model, estimates of relatedness change in concert with the population mean phenotype and variance, even when holding evaluator and partner phenotypes constant. This indicates that evaluators additionally require information about the distribution of phenotypes in the population. We outline an expanded concept of phenotype matching that accounts for evaluator, partner, and population phenotypic information. We measure this account against published findings and generate new hypotheses to test in the future.

4:00 Evidence for specialized processing of facial kinship cues Lisa DeBruine, Benedict Jones, Debra Lieberman, Craig Roberts (contact: [email protected]) Many aspects of face processing, such as identity, gender and normality judgments, are severely disrupted by inversion. This inversion effect is thought to be a hallmark of configural processing, while featural processing is unimpaired by inversion. Previous research shows that gender-related physical differences between adult sibling faces influence similarity judgments, but not kinship judgments (i.e., gender differences are “discounted” when judging kinship). Since similarity judgments and gender discrimination are impaired by inversion, if kinship perception is simply a combination of the perceptual mechanisms for judging similarity and gender, then kin recognition should be disrupted by inversion for same-sex pairs and even more severely for opposite-sex pairs. However, here we find that inversion does not disrupt allocentric kin recognition for either same-sex or opposite-sex pairs, suggesting that kin recognition mechanisms may be relatively specialized and not simply a by- product of general face recognition mechanisms.

4:20 Should I stay or should my siblings go? Sibship effects on dispersal behaviour Aïda Nitsch, Charlotte Faurie, Virpi Lummaa (contact: [email protected]) Understanding dispersal behaviour and its determinants is critical for studies on life history maximising strategies. Though many previous studies have investigated the causes of dispersal, very few have focused on the importance of sibship, especially in humans. Using a large demographic historical dataset (n=4000), we investigate the influence of sibling competition and cooperation on dispersal behaviour. Specifically, we test whether the probability, the timing and the range of dispersal depend on the presence of same-sex or opposite-sex siblings and on their reproductive status. This study is the first to investigate in detail the importance of siblings’ interactions for dispersal behaviour in humans and has important implications for the understanding of the evolution of family dynamics and fitness maximising strategies in humans and in other species.

87 Poinciana 3/4 Mating II 3:20 Men’s, but not women’s, sociosexual orientation predicts couples’ perceptions of sexually dimorphic cues in own-sex faces Michal Kandrik, Corey Fincher, Benedict Jones, Lisa DeBruine (contact: [email protected]) Previous research suggests that perceptions of own-sex individuals can change according to within-subject variation (e.g., cyclic shifts) in their romantic partners’ sexual strategies. However, little is known about how more stable, between-subjects differences in partners’ sexual strategies predict perceptions of own-sex individuals. The revised Sociosexual Orientation Inventory (SOI-R) assesses individuals’ openness to uncommitted sexual relationships and shows high test-retest reliability over long periods of time. We tested whether the SOI-R scores of men and women in romantic couples predicted their perceptions of own-sex faces. Men’s, but not women’s, SOI-R was positively correlated with the extent to which both partners ascribed high dominance and attractiveness to own-sex faces with exaggerated sex-typical cues (i.e., masculine men and feminine women). These findings suggest that both men’s and women’s perceptions of potential competitors for mates are sensitive to the male partner’s sexual strategy, potentially benefiting men’s ability to compete for extra-pair and/or replacement mates and women’s mate guarding behaviors.

3:40 A cross-cultural confirmation of sex difference of responses to imagining a partner’s heterosexual or homosexual affair Mark Cloud, Stephanie De Jesus (contact: [email protected]) Employing both a local and international sample, we tested the robustness of the finding that men, in contrast to women, are more likely to continue an imagined long-term relationship following a partner’s homosexual affair compared to heterosexual affair (Cloud & Confer, 2011). We predicted that the interaction would remain independent of all the moderator variables assessed including age, education, marital status, religion, and nationality. Participants (N = 327) were randomly assigned to read one of two affair scenarios and estimate the likelihood that they would continue the relationship. Participants were also assessed on how they would first respond to their partner and perpetrator. Although many moderator variables affected willingness to continue the relationship, none modified the underlying interaction between sex and affair type. A separate analysis of the likely responses to partners and perpetrators highlight additional sex differences. These results support sexual strategies theory predictions that men and women are differentially motivated to terminate relationships in response to a partner’s infidelity.

4:00 Effects of paternal age and early development conditions on attractiveness and number of children Martin Fieder, Susanne Huber (contact: [email protected]) Most of the de- novo mutations are explained by the age of the father at conception (Kong et. a. 2012). On basis of the Wisconsin longitudinal sample we show that a general and complex trait such as physical attractiveness is significantly associated with paternal age at birth but not maternal age at birth. We therefore hypothesize that this trait might signal an individual’s de novo mutation rate. Furthermore we show that only increased paternal age at birth is also related to a lower offspring count, controlling for attractiveness and SES. In addition, an individual’s attractiveness appears to be a sign of the conditions present during early development as father’s education was also significantly associated with physical attractiveness: individuals with fathers of very low educational background are rated as less attractive.

4:20 Seasonal changes in testosterone levels and body composition among rural Polish men Louis Calistro Alvarado, Melissa Emery Thompson, Magdalena Klimek, Martin N. Muller, Ilona Nenko, Grazyna Jasien (contact: [email protected]) The steroid hormone testosterone supports male secondary sexual characteristics, including sexually dimorphic musculature in humans. However, we found that because of the physical demands from increased provisioning responsibilities, fathers augmented strength and musculature despite age-related decline in testosterone. Here, we extend this research by investigating whether seasonal shifts in men’s workload are associated with shifts in testosterone production. Data were collected from 103 men in rural Poland (at the Mogielica Human Ecology Study Site), in a community where subsistence requires intensive manual labor. Increased workload during the summer harvest was accompanied by a reduction in circulating testosterone, together with muscular hypertrophy and increased strength. Relaxed workload during the winter was associated with both decreased muscle mass and strength, despite concomitant elevations in testosterone. Although the role of testosterone in maintaining skeletal muscle is often emphasized, these data suggest the importance of provisioning and subsistence activities in determining male phenotype.

88 Thursday, July 18

LATE AFTERNOON SESSION

Americana Salon 1 Cooperation IV 5:00 Preferential interaction and large-scale cooperation: The issue of perspective switching Jun-Hong Kim, Darryl Holman, Steven Goodreau (contact: [email protected]) Cultural’ group selection is considered a plausible mechanism for human altruistic propensities and large-scale cooperation. Here, we examine the structure of cooperation in a city-wide scale in Pohang, South Korea. First, we present a new method to empirically test a fundamental condition for the evolution of altruism: preferential interaction among prosocial individuals. We test this by quantifying preferential interaction using social network analysis of friendship networks. Having established the existence of preferential interaction, we examine whether the structure of individual friendships is correlated with neighborhood quality. To explore the complementarity between social group structure and preferential interaction, we compare social network measures of assortment (e.g. average degree) and neighborhood quality measures (e.g. average prosociality and social support within each neighborhood). The result suggests a substantial between-neighborhood variation in assortment and neighborhood quality measures as well as positive correlation between the two.

5:20 Gossip, reputation and sharing in Central African foragers Nicole Hess, Edward Hagen (contact: [email protected]) We collected social network and kinship data on a sample of forty adult Aka foragers in the the Central African Republic. Thirty-one informants reported on the entire sample, identifying their same-sexed friends and rivals in various domains (e.g., rivals in mating, singing, working, etc.). Informants identified and rated the extent to which members of the sample [i.e., “targets”]: (1) shared with others (2) were shared with by others, (3) worked hard, (4) parented well or poorly, (5) exhibited anger, and (6) sought multiple mates. We also asked (7) the informant’s opinion of the behavior of the target (positive to negative), as well as (8) a ‘gossip’ measure: whether other members of the camp said positive or negative things about the target. Controlling for kinship, close friendship, and rivalry, we tested the hypotheses that those who shared more, worked harder, parented well, and exhibited little anger would be shared with more (i.e., receive more benefits) from others, would be held in high opinion by others, and would have positive things said about them. Results generally supported the predicted relationships among gossip, reputation, and receipt of benefits.

5:40 Trust dynamics in the social construction of cooperation: An empirical analysis Cristina Acedo Carmona, Antoni Gomila Benejam (contact: [email protected]) Different approaches and disciplines have targeted trust as a main factor favoring cooperation among humans. However, the concept of trust taken for granted is not always the same. In experimental economics and evolutionary game theory in particular, the notion of trust is rather narrow, just a kind of prediction of the partner's behavior. In this new study, we tried to remedy this situation by developing a game approach that allows to analyze how particularized, interpersonal trust, fosters cooperation, even if anonymity is preserved. The study, carried out in different groups, uses a vision of trust based on interpersonal experiences with bonds of loyalty emotionally motivated acquired during the evolutionary process of human species, which create a mutually accepted compromise and positive disposition through expectations about the others’ behavior. Here we present our study results and suggest the influence of the social networks structure on the achieved degree of cooperation.

6:00 Why do people selectively give benefits to cooperators in SD? Nobuyuki Takahashi, Misato Inaba (contact: [email protected]) Recent studies suggest that cooperators can be adaptive because they receive benefits in other situations (e.g., Milinski et al., 2002; Panchanathan and Boyd, 2004; Vyrastekova and van Soest, 2007). However, why people selectively give benefits to cooperators in other situations, which is conceptualized as ‘linkage’(Aoki, 2001), has not been fully investigated. We propose that impression formation is the proximate mechanism that enables linkage. We hypothesized that linkage would occur only when internal attribution, which is necessary for impression formation, is possible. In order to test this hypothesis, we conducted an experiment in which participants played a one-shot SD followed by a repeated PD. We manipulated whether or not behaviors in SD are internally attributable. In the intention condition, participants were told that their partners could choose their behaviors in SD. In the no intention condition, they were told that their partners had no choice but to cooperate/defect in SD. The results showed that participants cooperated more with SD cooperators than with SD defectors only in the intention condition.

89 Americana Salon 2 Aggression III 5:00 Representations of relative formidability and social cognition Daniel Fessler, Colin Holbrook, Jeremy Pollack, Jennifer Hahn-Holbrook (contact: [email protected]) In situations of potential agonistic conflict, decision-making hinges on the likelihood of victory and the costs incurred in the event of defeat. Likelihood of victory is contingent on the parties’ relative formidabilities. Reflecting both their phylogenetic antiquity and their ontogenetic ubiquity, physical size and strength loom large in one-on-one conflicts. Selection has coopted the ability to represent these traits, such that size and strength form the dimensions of representations used to summarize diverse determinants of relative formidabilities. Attributes that increase the costs of defeat are captured by the same summary representation. Experimental results demonstrate that physical incapacitation increases the conceptualized size and strength of an antagonist and decreases estimates of own size. Likewise, both the presence of children and the status of parenthood independently contribute to increased estimations of an antagonist’s size and strength. Ongoing experiments probe multiple facets of the role of representations of relative formidability in social cognition.

5:20 Resource conflict and the asymmetric war of attrition in children Alex Shaw, David Pietraszewski (contact: [email protected]) People interact with others in a world that has limited resources; so knowing when to engage in conflicts over these resources is essential. Evolutionary models argue that certain factors should be used by agents to make predictions about fight outcomes in order to prevent agents from incurring costs by engaging in fights that they are unlikely to win. These models predict that agents should use other agents’ formidability and the subjective value those agents place on a resource to decide whether or not to engage in a fight with them over that resource (Maynard Smith & Price, 1973). We investigated if 6- to 8-year-old children use these factors to predict the outcome of conflicts. We read children vignettes about individuals who were fighting over a resource and asked them to predict who would win the conflict. Our results indicate that children use formidability (e.g. the agents; size and strength) and the subjective value placed on a resource (e.g. whether the agent owns the object or is hungry) when determining who will win a conflict over that resource.

5:40 Face of a fighter: Bizygomatic width as a cue of formidability Samuele Zilioli, Aaron Sell, Neil Watson (contact: [email protected]) Humans can accurately extract information about men’s formidability from the face, however, the actual facial cues that inform these judgments have not been identified. Here, through five studies, we tested the hypothesis that bizygomatic width (i.e. width-to-height ratio) covaries with physical formidability and that humans use this cue when making assessments of formidability. First, we showed how it is predictive of actual fighting ability, as indicated, in study 1, by the number of fights (and wins) in professional combatants (after controlling for fighters’ size and years of activity); and, in study 3, by the actual upper body strength in an undergraduate sample. Next, we found how this testosterone-linked facial feature is used by people in estimating fighting ability not only from artificial, exaggerated images (i.e. morphs, studies 2a and 4), but also from photos of real professional combatants (study 2b) as well as undergraduate students (study 3).

6:00 The importance of physical strength to human males Aaron Sell (contact: [email protected]) Fighting ability has received little attention as an explanatory variable in the social sciences, but evolutionary biologists have found it to be an indispensable construct for understanding animal aggression. Specifically, in species with an evolutionary history of conspecific aggression, larger more formidable animals are more aggressive and seek out larger shares of resources. Human males, but not females, have had such a history of aggression. Because of this evolutionary history of aggression, male psychology should have evolved such that a man’s propensity toward violence, sense of entitlement, and attitudes about aggression and warfare are calibrated by his fighting ability. Several studies are presented showing that physically stronger men are more prone to aggression and anger, feel entitled to better than average outcomes, have self-favoring political attitudes, and are more supportive of military action. No such effects were found for stronger women. Results were replicated in seven studies from five different cultures, including industrial societies, hunter-gatherers and hunter-horticulturalists.

90 Americana Salon 3 Symposium: The impact of life history strategies on perceptions, psychopathology, and menarche: Experimental and longitudinal evidence Organizers: Chiraag Mittal and Jeffry A. Simpson 5:00 Harshness, unpredictability, and age of menarche: A life history approach Jeffry A. Simpson, Vladas Griskvicius, Sooyeon Sung, Sally I. Kuo (contact: [email protected]) In this longitudinal study, we tested how two different types of stress (harshness and unpredictability) experienced at different points during developmental where related to age of menarche in girls. Exposure to more unpredictability within the home during the first two years of life uniquely predicted earlier age of menarche, statistically controlling for harshness and unpredictability at other developmental periods. Importantly, however, infant attachment security moderated these findings, such that females who had secure attachment relationships with their mothers early in life (assessed in the Strange Situation), relative to females who had insecure relationships, were buffered from the negative impact of early unpredictability within the home by having menarche at a later age. Females who experienced earliest menarche were those who both had unpredictable home environments and also had an insecure relationship with their mothers very early in life. These findings are discussed in the context life history theory and different reproductive strategies.

5:20 Fat, fertility, & fast strategies: The effect of ecological harshness on the ideal female body size Sarah E. Hill, Danielle DelPriore, Christopher D. Rodeheffer, Max Butterfield (contact: [email protected]) Why do researchers regularly observe a relationship between ecological conditions and the heaviness of female body weight ideals? The current research uses insights from life history theory and the critical fat hypothesis to examine whether this variability might emerge from the different life history strategies typically adopted by those living in harsh versus benign ecologies. Across three experiments, we demonstrate that women who were sensitized to faster life history strategies during development – as indexed by early menarche or low childhood SES – respond to cues of ecological harshness by shifting away from the sub-fertile body ideal typically chosen by Western women toward a heavier, more fertile female form. Additionally, although men’s perceptions of the ideal male body size did not shift in response to these cues, their perceptions of the ideal female body size did, with developmentally sensitized men also preferring a heavier female body size in this context.

5:40 Evolutionary psychopathology: A unifying life history framework Marco Del Giudice (contact: [email protected]) In this talk I outline a unifying framework for evolutionary psychopathology based on the concepts of life history theory. My analysis centers on the novel distinction between fast spectrum and slow spectrum disorders. I describe four causal pathways from life history to psychopathology, argue that psychopathology can arise at both ends of the fast-slow continuum, and provide heuristic criteria for classifying disorders as fast or slow spectrum pathologies. The fast-slow distinction applies to a broad range of diagnostic categories including externalizing disorders, schizophrenia spectrum disorders, autism spectrum disorders, obsessive-compulsive disorders, eating disorders, and depression. The framework I present integrates previously disconnected models of psychopathology within a common system, and has broad implications for the classification of mental disorders. I conclude by discussing how a life history perspective provides an elegant and heuristically fertile approach to the core themes of developmental psychopathology—the interplay between normality and pathology, between risk and protective factors, and between continuity and discontinuity in development.

6:00 Psychological drivers of fast and slow life history strategies: The sense of personal control Chiraag Mittal, Vladas Griskevicius (contact: [email protected]) Past research finds that environmental harshness and uncertainty leads people to behave differently depending on their childhood. For example, when resources are scarce, people reared in poor childhood environments become more impulsive, whereas those reared in wealthy environments delay gratification. Why do people respond to scarcity cues in these diverging ways? Drawing on life history theory, the current research examined the psychological mechanism underlying responses to resource scarcity, testing whether perception of control drives these effects. A series of experiments provide evidence that scarcity cues alter perceptions of control. Whereas people reared in poor environments perceive having less control, those reared in wealthy environments increase perceptions of control. Additional findings showed that perception of control not only mediated the effects of resource scarcity on impulsivity, but it also altered persistence behavior. Whereas scarcity cues led people from poor backgrounds to quit a challenging task sooner, they led people from a wealthy environment to persist longer.

91 Americana Salon 4 Kinship II 5:00 Effects of sex and relatedness on levels of sibling conflict Catherine Salmon, Jessica Hehman (contact: [email protected]) From a Darwinian perspective, sibling conflict should increase as level of relatedness decreases. For example, higher levels of conflict would be expected between non-biological siblings relative to biological siblings and greater conflict between half- siblings than between full siblings. Despite the importance of sibling relationships across the lifespan, this question about levels of conflict and relatedness has largely gone untested in the literature. In this study, we investigated levels of sibling conflict as a function of sex of participant, sex of sibling, and degree of relatedness in a college sample. Significant interactions were found between sex of participant, sex of sibling, and degree of relatedness such that males had more conflict with same sex siblings and more conflict with unrelated siblings. The implications of our results for understanding sibling relations and conflict over parental resources will be discussed.

5:20 Kin investment by stepgrandparents: More than expected Alexander Pashos, Sascha Schwartz, Donald H. McBurney, David F. Bjorklund (contact: [email protected]) In accordance with kin selection theory, stepgrandparents (SGPs) should not invest substantially in stepgrandchildren (SGC) and their investment should not be asymmetric, because no consanguinity exists and hence no differences in kinship certainty. However, coresidence with biological grandparents might affect SGPs’ caregiving in a positive direction. Using two questionnaire samples from Germany and the USA (Pittsburgh), we identified different types of SGPs and analyzed their kin caregiving as reported by their SGC. From a total of 515 respondents, 115 subjects had one or more SGPs in their childhood. There were no differences in the results from Germany and the USA. Subjects named type I SGPs (spouses of biological grandparents) much more often than type II SGPs (parents of stepparents). The ratings for SGPs were relatively high and comparable to biological grandparents. Stepgrandfathers provided more care than stepgrandmothers for SGC. This applied, however, only for type I SGPs, i.e. husbands of biological grandmothers. For interpretation, we discuss the role of coresidence, laterality, marriage status and alternative investment options through biological grandchildren.

5:40 Maternal kin take on the care of children in more challenging circumstances than paternal kin Gretchen Perry, Martin Daly (contact: [email protected]) We studied kin placements of children who had been removed from their parents in Waterloo Region, Canada between January 2008 and December 2010. Although child protection legislation defines “kin” very broadly, 55% of all kin placements were in fact with grandparents and an additional 23% with other close relatives (r ≥ .125) of the child. Except for a preponderance of paternal over maternal uncles, maternal kin greatly outnumbered paternal. This might, in principle, reflect agency practice rather than caregiver preferences, but further analysis suggests that differential inclinations play a role. The more difficult the placement family’s circumstances, the larger the preponderance of maternal kin, and lone grandparents providing care without a partner’s help were overwhelmingly maternal. These patterns are consistent with the hypothesis that maternal and paternal relatives have different thresholds for coming forward.

6:00 Reproductive competition and co-operation between siblings in the matrilineal Mosuo of southwestern China Ruth Mace, Ting Ji, Jia-Jia Wu, Qiao-Qiao He, Jingjing Xu, Yi Tao (contact: [email protected]) The matrilineal Mosuo of southwestern China live in communal households where brothers and sisters of three generations live together, and men visit their wives, who reside elsewhere, only at night in ‘visiting’ marriages. Here we show that communally breeding sisters, but not brothers, are in reproductive conflict. We use a ‘tug-of-war’ model of reproductive skew generated by incomplete control, to model the patterns of effort put into competition between sisters. The model predicts that older (dominant) sisters will put more effort into communal activity than will younger sisters, and younger sisters will put more effort into selfish activity; but the models also predict the younger sisters will also have lower reproductive success. Both predictions are supported by our data suggesting that older sisters maximise their reproductive success by allowing their younger sisters some reproduction, but whilst they have more offspring than do younger sisters, they also work harder in the fields.

92 Poinciana 3/4 Culture: Language 5:00 Optimal investment in reputation: A prejudist's approach Alexander Funcke (contact: [email protected]) Consider a population that repeatedly plays a 2-persons coordination games with randomly drawn opponents from a population. Due to path dependency the population may get stuck in a sub-optimal coordination, playing dominated strategies. Given such a situation, under what conditions is it in one's interest to invest in a reputation of being a player of the dominating strategy? To approach this, I model agent belief formation regarding their opponent's strategy choice as a probability inferred through prejudice. The prejudgment here is modeled as the probability yielded by considering the ratio of the aggregated frequencies of each strategy's inverses weighted distance between the characteristics vector of the current opponent and the vector of each previous players. This model also suggests that it is sometimes is sound to invest in not only in ones reputation, but also in ones appearance; when it is feasible to be an iconoclast and when one ought not too. It also gives us a hint why it may be hard to escape stereotypical behavior.

5:20 Tracing human cultural ancestry in time and space Quentin Atkinson (contact: [email protected]) Recent work on cultural evolution has successfully applied phylogenetic methods from biology to comparative cultural and linguistic data to test hypotheses about cultural ancestry, chronology and sequences of change. However, relatively little attention has focused on explicitly modelling large-scale spatial processes of cultural change. Here I report results from a range of collaborative research projects that uses tools from population genetics and phylogeography to analyze spatial information derived from comparative cultural data. This work identifies the legacy of phylogenetic and spatial processes in a range of cultural data.

5:40 On the role of analogy in cultural transmission and human dispersal Marshall Abrams (contact: [email protected]) Research on cultural transmission, including modeling, field work, and laboratory experiments, has not not focused much on how adoption of some cultural variants affects transmission of others. The importance of interactions between cultural variants is suggested by some anthropologists' conceptions of culture as constituted by interacting thought processes, linguistic elements, behaviors, or practices; by research on reasoning and cognitive dissonance in psychology; and by epistemological research on the role of coherence in justification. Work in anthropology and cognitive science also suggests that analogies between cultural variants sometimes bias adoption of variants. While analogy can motivate spurious inferences, it's been argued that it plays beneficial roles in scientific practice and in routine problem solving. I argue that analogies between cultural variants can bias cultural transmission, and may have played an important role in human dispersal by facilitating adaptation to new environments. I illustrate these possibilities using agent-based models that incorporate cognitive models of analogy processing, and propose methods for empirical study.

6:00 The extent of combinatorial communication in nature, and its relevance for the origins of language Thom Scott-Phillips, James Gurney, Al Ivens, Stephen Diggle, Roman Popat (contact: [email protected]) One distinctive feature of human language is that its component parts are combined together into higher-order sequences, with effects that are not simply the sum of the effects of the component parts. This feature is otherwise rare in nature: it appears to exist in a simple form in some non-human primates, but has not been demonstrated in other species. This observed distribution has lead to the suggestion that these differences reflect cognitive differences between species, and hence that the combinations we see in non-human primates are evolutionary pre-cursors of human language. Here we replicate the landmark experiments in non-human primates, but in a species that is unrelated to humans, and which has no higher cognition: the bacterium Pseudomonas aeruginosa. Using the same general methods as the primate studies, we find the same general pattern: the effect of the combined signal differs from the sum of the effects of the two individual signals. This suggests that higher cognition does not explain why some species use composite signals and others do not, and that it is premature to conclude that the systems observed in non-human primates are evolutionarily related to language.

93 Friday, July 19

EARLY MORNING SESSION

Americana Salon 1 Life History I 10:20 The impact of sex ratio and economic status on local birth rates Abby Chipman, Edward Morrison (contact: [email protected]) Human mating and reproductive behaviour can vary depending on various mechanisms including the local sex ratio. Previous research shows that as sex ratios become female-biased, women from economically deprived areas are less likely to delay reproductive opportunities to wait for a high-investing mate but instead begin their reproductive careers sooner. Here, we show that the local sex ratio also has an impact on female fertility schedules. At young ages, a female-biased ratio is associated with higher birth rates in the poorest areas, whereas the opposite is true for the richest areas. At older ages, a female-biased ratio is associated with higher birth rates in the richest, but not the poorest areas. These patterns suggest that female-female competition encourages poorer women to adopt a fast life history strategy and give birth early, and richer women to adopt a slow life history strategy and delay reproduction.

10:40 Socio-demographic influences on sex ratio at birth (SRB): A comparative study Bernard Wallner (contact: [email protected]) Environmental and socio-demographic factors can influence the variation of SRB (number of males/number of males plus females). This work investigated the effects of females’ socio-economic status on SRB in humans and a non-human primate species, the Barbary macaque, using three different data sets. In our first sample we examined the SRB in a Western population of mothers working at the University of Vienna, with regard to different educational levels, academics versus non-academics (N=1,184). The second study analyzed the effects of ownership of dwellings on a Ugandan sample (N=438,640) and the macaque study analyzed SRB in relation to maternal dominance rank (N=12). Multivariate statistics of demographic and social variables regressed on SRB showed increased male births in mothers who live under favorable environmental conditions: (i) for academics during spring season, (ii) for Ugandan mothers who owned a dwelling and (iii) for macaque females who were members of high ranking maternal lineages. These results give evidence for both the maternal dominance and the better environmental condition hypothesis.

11:00 Wealth inequality, social capital, health, and life history strategy in Tsimane forager-horticulturalists Aaron Blackwell, Adrian Jaeggi, Jonathan Stieglitz, Paul Hooper, Hillard Kaplan, Michael Gurven (contact: [email protected]) Wealth inequality (WI) has been linked to negative health outcomes in both industrialized and subsistence populations. A number of hypotheses for this link have been proposed, including lack of coordination in public goods, loss of social capital, and stress due to status and success inequalities. Here, we propose that biological outcomes may also be affected by specialization of life history strategies, particularly where inequality is stable and both inequality and life history strategies are at least partially inherited across generations. To test this we examine the effects of WI on anthropometrics and trade-offs between anthropometrics and immune function in Tsimane horticulturalists. We find that adolescent and adult male heights increases in variance in villages with high WI. In these villages male height is correlated with household wealth. Moreover, in high WI villages shorter individuals have higher immune function measures. Although these findings are consistent with life history specialization, we also find that the number of household meat sharing partners is negatively associated with WI, suggesting changes in social capital may also be important.

94 Americana Salon 2 Cooperation V 10:20 Do social preferences drive biologically altruistic behavior? Alejandro Rosas (contact: [email protected]) Economic experiments report that social preferences drive human cooperation and punishment. We punish for the sake of enforcing norms, not for the sake of expected benefits. Some researchers believe, moreover, that punishment is biologically altruistic: it involves a lifetime loss in fitness and evolves through GS. The point about preferences is psychological and concerns proximate mechanisms. It does not entail, nor is evidence for, biological altruism. Field evidence does not provide confirmation, and suggests rather that punishment is not costly for punishers in the long run. In this paper i criticize a model that captures some lab evidence for biologically altruistic punishment (Bowles and Gintis, 2011). It is based on the idea that punishment is conditional on a quorum of punishers within each group. I analyze what happens before and after the quorum is reached, and show that in neither case can GS be held responsible for the invasion of punishers. The model may capture real life punishment, but it is not a GS model. The criticism is constructive: it is time to acknowledge that social preferences do not need group selection to evolve.

10:40 The effect of power asymmetries on cooperation and punishment in humans Jonathan Bone, Nichola Raihani (contact: [email protected]) The evolution of cooperative behavior is a major evolutionary puzzle, although individuals should benefit from selfish behaviors, examples of altruism are prevalent throughout nature. Whilst some studies have shown that punishment sustains cooperation, others have found that punishment can destabilize cooperation when punished individuals retaliate. Most studies to date have assumed that all players are equal in terms of power such that punished individuals can readily retaliate against aggressors. However, in reality, punishment is expected to operate down a dominance hierarchy, with dominants more likely to punish subordinates, who are unlikely to retaliate. The effect of power asymmetries on punitive behavior has not yet been tested in studies of human cooperation. We ran an experiment to test how incorporating power asymmetries into a two player iterated prisoner’s dilemma (IPD) game affects the use and effectiveness of punishment. Experiments that incorporate such variations are a vital next step towards fully understanding the evolution of punishment and cooperation in nature.

11:00 Possible roles for punishment and reward from an evolutionary perspective Jennifer Jacquet (contact: [email protected]) Costly punishment has shown to be much more effective at enhancing cooperation in public goods experiments than costly reward (Milinski & Rockenback 2012). Furthermore, punishment has been widely documented for transgressions in non- human animals (e.g., ant species, hamadryas baboons, chimpanzees, and client fish toward cleaner fish; Clutton-Brock & Parker 1995, Bshary & Grutter 2002). Here, I argue that punishment’s most important evolutionary function in humans was for controlling social transgressions, while reward has been more important for encouraging social transmission and innovation, and helped to catalyze the prestige culture that developed alongside the dominance hierarchy in human societies (Henrich & Gil-White 2001). Of course, the boundaries are not perfectly delineated. For instance, our work on shame and honor showed that both were effective at increasing cooperation in a public goods experiment (Jacquet, Hauert, Traulsen, & Milinski, 2011). In general, however, punishment is more important to cooperation owing to the asymmetry of social dilemmas, where the failure to cooperate by individuals often destabilizes cooperation for the entire group.

95 Americana Salon 3 Symposium: Evolutionary medicine: A survey of important advances in the field Organizer: Paul Andrews 10:20 Alzheimer’s Disease and the evolution of longevity Molly Fox (contact: [email protected]) Would long-lived individuals in the ancient past have had net beneficial or detrimental effects on their families? In the modern industrialized world, the inclusive fitness benefits of longevity are attenuated by the burden of having an elderly parent with Alzheimer’s. To understand how natural selection shaped the human lifespan, we need to recreate what Alzheimer’s prevalence and risk might have been throughout our species’ past. I propose that the genetic and lifestyle factors that increase Alzheimer’s risk today may have functioned differently in past environments, rendering Alzheimer’s a far less common affliction among the elderly before certain changes arose in human hisoty. Using data from a variety of sources including my fieldwork in rural England, I present evidence for a ‘mismatched environment’ explanation for the high prevalence of Alzheimer’s in the industrialized world today. Applying principles of evolutionary theory towards investigating the root of geriatric cognitive decline has the potential to contribute not only to medical research, but also towards a clearer interpretation of the evolutionary forces that shaped the human life-history.

10:40 Sugar and ice and everything nice: an evolutionary approach to age and sex differences in substance use Edward Hagen, Casey Roulette, Roger Sullivan (contact: [email protected]) Psychoactive drugs are widely used, it is thought, because they inadvertently activate reward-related neural circuitry. Under this model, drugs should be equally appealing to children and to adults of both sexes. Many drugs are plant defensive chemicals, however. We therefore argue there should be important differences in substance use across the life span and between the sexes that are explained by drug toxicity. In particular, children, and to a lesser extent adult women, almost certainly evolved to avoid drugs to protect their, or their fetuses', developing nervous systems, respectively. We test these ideas against national and cross-national datasets, and find virtually no substance use among children; a switch-like transition to substance use in adolescence; and a nearly universal male bias in substance use. We argue that around the age of 15, emerging benefits of substance use, especially defense against parasites and honest signaling to potential mates, start to outweigh diminishing costs of exposure, especially for males.

11:00 On the function of placental corticotropin-releasing hormone: a role in maternal-fetal conflicts over blood glucose concentrations Steven Gangestad, Ann Caldwell-Hooper, Melissa Eaton (contact: [email protected]) During the last two trimesters, the human placenta produces substantial quantities of corticotropin-releasing hormone (placental CRH), most secreted into the maternal bloodstream. Placental CRH stimulates production of maternal cortisol, leading cortisol levels to rise during the third trimester, an effect puzzling in light of widespread theory that cortisol harms the fetus. Indeed, the maternal HPA axis becomes less sensitive to cortisol during pregnancy, purportedly to protect the fetus from cortisol exposure. Researchers, then, have speculated that the beneficial effects of placental CRH involve receptors outside the HPA system, such as the uterine myometrium (e.g. the placental clock hypothesis). An alternative view is presented: Placental CRH benefits the fetus because it does stimulate the production of cortisol, which, in turn, leads to greater concentrations of glucose in the maternal bloodstream available for fetal consumption. Maternal HPA insensitivity to placental CRH may reflect counter-adaptation, as the optimal rate of cortisol production for the fetus exceeds that for the mother. These mechanisms may hence be outcomes of maternal-fetal conflicts (Haig, 1993).

96 Americana Salon 4 Emotion I 10:20 Status, individual differences, and emotional reactions to threat Beatrice Alba, Doris McIlwain (contact: [email protected]) Negotiating status hierarchies is one of the key adaptive problems that humans face, and it is argued here that emotion plays a significant role in this task. Existing research has found that the expression of anger is associated with high-status, and that contempt is associated with viewing others as incompetent. This research explored these issues further with a series of studies investigating social status and its relationship to the emotions. In addition, individual differences were also examined in these studies through the use of an original scale created by the researchers measuring individual differences relating to status striving and perceived superiority. It was found that perceived superiority predicted contempt, and that different emotions occured in reaction to threat depending on gender. It is argued here that one of the adaptive functions of emotions is to serve the purpose of manipulating others in order to gain or maintain status.

10:40 Shades of green: The functional distinction between benign and hostile envy Rachel Falcon (contact: [email protected]) Envy functions in resource competition situations in which a competitor out-competes oneself in a fitness relevant domain (Hill & Buss, 2006, 2008). Research suggests that there are two types of envy, a hostile version, aimed at dragging the envied person down to one’s own level, and a benign version, aimed at raising oneself up to the level of the envied person (Parrott, 1991; van de Ven, Zeelenberg, & Pieters, 2009). Three predictions were derived from the hypothesis that the selection of envy type is functional, taking into account the costs and benefits of a benign versus a hostile response: 1) Hostile envy was expected to be more likely when the resource can’t be acquired without taking it from the envied. 2) Benign envy was expected to be more likely when the relationship with the envied person is highly valuable to the envier. 3) Benign envy was expected to be more likely when the social environment favors then envied person. Using a daily diary method, participants described over 400 occasions of actual envy, which were categorized as benign or hostile based on a taxometric analysis. Comparisons across the two types provided support for predictions 2 and 3.

11:00 Gratitude and interpersonal welfare valuation Adam Smith, Debra Lieberman, Eric Pedersen, Daniel Forster, Michael McCullough (contact: [email protected]) Gratitude functions to foster human sociality. Exactly how gratitude performs this function, however, is a question that has received remarkably little scientific attention. Many recent investigations—primarily concerned with the positive social and emotional outcomes associated with the experience of gratitude—have overlooked the fundamental mechanistic operations that permit gratitude to be experienced in the first place. Our work addresses this oversight by capitalizing on advancements in the evolutionary psychological study of function, information processing cognitive mechanisms, and internal regulatory variables. We hypothesize that gratitude is a psychological adaptation that functions to catalyze and sustain interpersonal relationships by altering an internal regulatory variable responsible for tracking interpersonal welfare valuation known as the Welfare Tradeoff Ratio (WTR). Initial tests of this hypothesis show that gratitude causes beneficiaries to increase the degree to which they value the welfare of their benefactors, measurable as an increase in WTR. Related findings will also be discussed.

97 Poinciana 3/4 Symposium: Facing challenges and evolutionary happiness in Latin America Organizer: Jorge Yamamoto 10:20 Migration from a traditional Inca´s village to a modern city: Changes in goals, resources, and its well-being correlates Cinthya Diaz (contact: [email protected]) Q'ero communities are known as the last Inca villages as they kept alive the ancient lifestyle, however, migration to the urban city of Cusco is now observed. In both of these contexts, we study the differences in subjective well-being and adaptation as a product of migration. Open-ended interviews were conducted, and results reveal that life goals and resources of the Q’ero villagers become adapted to the requirements of urban life in the Q’ero migrants to Cusco city. Some resources are maintained in both sides, however they can assume different functions; e.g. ancestral rituals are used by Incas villagers to obtain fortune, while in Cusco city, the same ancestral rituals are organized to entertain tourists (and to obtain some fortune). Wellbeing correlates in urban and rural contexts are discussed.

10:40 Decision to get pregnant and subjective well-being improvement in adolescent mothers in extreme poverty in Peru: An adaptive strategy, not an accident Brenda Chavez (contact: [email protected]) Adolescent motherhood is taken as a public health issue in most countries. However various research studies around the globe have been discussing that some adolescents find a favorable way in early childbearing. This paradoxical evidence required a scientific study about the perspective of the adolescent mothers. We describe the subjective life satisfaction before and after pregnancy in 96 adolescent mothers living in extreme poverty in Peru shantytowns. An ad-hoc emic scale was developed in order to avoid Western-Modern Researcher bias. Results show that a group of mothers in economical and familial critical conditions decided to get pregnant. Motherhood aggravates the material condition, but nonetheless their emotional condition is improved. These results suggest that teenage pregnancy may be an adaptive evolved response to a perception of critical life conditions. Implications for wellbeing intervention in social policy are discussed.

11:00 Adaptation and values change: modernization and unhappiness in rural fishermen village in Peru Dante Solano (contact: [email protected]) El Ñuro is a traditional rural community of fishermen on the North Coast of Peru. In recent years, the community has been undergoing a modernization process, which was marked by economic development and changes in community infrastructure. The present study aimed to describe this modernization process and evaluate the values change during 4-years period (2006 – 2010), through ethnographic reports and a longitudinal application of emic values survey. The results show a rapid modernization process in the community, accompanied by a reduction of traditional and interdependent values, suggesting that value change is part of the adaptation to new environmental challenges. Interdependent behavior and traditional lifestyles has been previously related to evolved activation of happiness feelings, because of interdependence and tribal behavior was critical for survival in human evolution. Therefore, this study provides evidence of one possible explanation of the negative relation between modernization and well-being found in previous studies.

98 Friday, July 19

LATE MORNING SESSION

Americana Salon 1 Life History II 11:30 Father absence and age at first birth: What can a review of the cross-cultural evidence tell us about what fathers do for their children? Rebecca Sear, David Coall (contact: [email protected]) The role of fathers varies considerably between populations: both direct and indirect paternal investment can take various forms, and the presence or absence of fathers in childhood has also been argued to be a useful indicator of both (1) the adversity of the environment, and (2) mating strategies common to the population. In order to tease apart these different (but not necessarily mutually exclusive) hypotheses for how fathers may influence their children’s subsequent reproductive behaviour, we review the existing literature on whether and how father absence or presence influences their children’s age at first birth. We find that studies of WEIRD (Western Educated Industrialised Rich and Democratic) populations consistently show that father absence leads to earlier first births in girls. The evidence for boys is more limited, but suggests a similar pattern of accelerated first births for boys in father absent households. Studies in less well nourished populations, however, show a more variable picture, with father absence sometimes accelerating first births but more often delaying offspring’s age at first birth, especially for boys.

11:50 Fostering relations: The differences in sexual and reproductive outcomes between children raised by kin and non-kin carers Susan Schaffnit, Paula Sheppard, Justin Garcia, Rebecca Sear (contact: [email protected]) Kinship fostering is often assumed to be superior to non-kin fostering despite inconsistent evidence of the advantages of either foster method. Using Original Kinsey Survey data, collected in the US from 1938 to 1963, we ran event history analyses to compare the effects of living with kin and non-kin fosterers in childhood on the timing of sexual and reproductive behaviours – age at first sex and marriage. We control for parental divorce and death to try to tease apart the effects of living with kin and non-kin from early life disruptions. We expect kin carers to act more similarly to biological parents than non-kin fosterers due to shared genetic interests between carer and child. Kin carers should shield children from premature sexual and reproductive behaviour and encourage slower reproductive strategies in order to invest in embodied capital, as parents do in low fertility societies. Our time-to-event analyses show that while kin fostered children do have somewhat accelerated life histories compared to children from intact families, kin fosterers buffer children from premature sexual and reproductive behaviours compared to children in the care of non-kin fosterers.

12:10 Early life adversity does not accelerate menarche in the Dogon of Mali Beverly Strassmann (contact: [email protected]) Previous studies have found that early life adversity, for example “father absence,” is associated with earlier menarche. Many of these studies use retrospective measures of childhood stressors and sexual maturation, making it challenging to determine causality. In a longitudinal study of the Dogon of Mali (from 1998 to 2012), covariates that provide a fine-tuned measure of the girl’s family environment (e.g. maternal or paternal absence and polygyny) were measured prospectively from infancy to adolescence. In a logistic regression that controlled for age and other confounding variables, none of the social variables indicative of early life adversity were predictive of menarcheal status in 2012 (N = 600 girls). Although the social variables were not predictive of menarcheal status, variables indicative of body size and growth trajectory were highly significant. In particular, girls who were stunted in the year 2000 were much less likely than non-stunted girls to have reached menarche by 2012 (P = 0.02 Odds ratio = 0.45). These results suggest the need to re-evaluate this topic.

99 Americana Salon 2 Cooperation VI 11:30 Conditional punishment depends not only on how it affects free riders but also how fellow cooperators act Sangin Kim, John Tooby, Leda Cosmides (contact: [email protected]) For a punishing strategy in a collective action to be selectively advantageous, the relative profits among potential punishers needs to be taken into account, as well as its effects on the target of punishment. Thus, the architecture underlying punishment is expected to sensitively respond to the distribution of its effects on all group members. For example, punitive sentiment toward a free-rider should interact with variables that are relevant to second order free riding. In the standard public goods game, assessing such effects is precluded by the game design because for example, players do not know others’ punishment levels. Using modified versions of the public goods game, we are able to investigate how punishment is dependent on others’ actions. The implications for current theories of human punishment will be discussed.

11:50 Incompetent, disabled, and unlucky: Specialization for distinguishing and tracking functionally distinct causes of non-contributions Theresa Robertson, Andrew Delton (contact: [email protected]) Pooling resources by sharing is a major benefit of human sociality, but is vulnerable to exploitation by non-contributors. Yet, resource pooling systems routinely make exceptions for unintentional causes of non-contribution, such as incompetence, disability, and bad luck (while intentional non-contributors (free riders) are punished or excluded). However, even if unintentional non-contributors are seen as cooperators, they may nonetheless be marked because they potentially pose unique risks and opportunities. For example, they must be monitored to ensure they are not masking free riding, and assistance should be preferentially targeted to disabled individuals and teaching to incompetent individuals. Consistent with predictions, incompetence, disability, and bad luck are not only spontaneously categorized separate from free riding, but also separate from each other. Predictable inferences follow from different causes of non-contribution. In addition, expected long-term contributions may be used to triage relationships when resources are scarce.

12:10 Do humans really punish altruistically? A closer look Eric J. Pedersen, Robert Kurzban, Michael McCullough (contact: [email protected]) Some researchers have proposed that natural selection has given rise in humans to one or more adaptations for altruistically punishing on behalf of other individuals who have been treated unfairly, even when the punisher has no chance of benefiting via reciprocity or benefits to kin. However, empirical support for the altruistic punishment hypothesis depends on results from experiments that are vulnerable to potentially important experimental artifacts. Here we searched for evidence of altruistic punishment in an experiment that precluded these artifacts. In so doing, we found that victims of unfairness punished transgressors whereas witnesses of unfairness did not. Furthermore, witnesses’ emotional reactions to unfairness were characterized by envy of the unfair individual’s selfish gains rather than by moralistic anger toward the unfair behavior. In a second experiment, we found that previous evidence for altruistic punishment plausibly resulted from affective forecasting error. Together, these findings suggest that the case for altruistic punishment in humans—a view that has gained increasing attention in the biological and social sciences—has been overstated.

100 Americana Salon 3 Symposium (cont.): Evolutionary medicine: A survey of important advances in the field Organizer: Paul Andrews 11:30 The impact of social stress on women’s health and fertility: An evolutionary life history perspective Athena Aktipis (contact: [email protected]) Recent research suggests that stress and early adversity may have profound effects on the female reproductive system, including altering follicular development and increasing susceptibility to certain cancers. Evolutionary life history theory provides a framework for understanding how early adversity and stress impact health and disease: Stressful conditions provide cues to the organism that can shift development towards faster reproduction at the expense of somatic maintenance. This may result in earlier fertility but also greater susceptibility to certain diseases. Our current work suggests that such life history tradeoffs may underlie susceptibility to aggressive breast cancer. There are many unrealized opportunities for applying evolutionary approaches to understanding the role of social factors in shaping female reproductive health and vulnerability to cancer and other diseases.

11:50 Hormones in the wild: Why psychosocial stress can make us sick Mark Flinn (contact: [email protected]) The hypothalamic-pituitary-adrenal stress hormone axis (HPAA) is highly responsive to traumatic experiences including social challenges. Because stress hormones can have negative developmental and health consequences, this presents an evolutionary paradox: Why would natural selection have favored physiological mechanisms that elevate stress hormone levels in response to psychosocial stimuli? Here I present results from a 25-year study of ‘hormones in the wild’ that explore the possible trade- offs between health and socio-cognitive challenges. Analysis of hormonal and morbidity data indicate a 2.7-fold increase in illness during a five-day period following some stressful events. Secure attachment and social support mitigate this effect.

12:10 Population level effects of suppressing fever Paul Andrews, David Earn, Ben Bolker (contact: [email protected]) Fever is commonly attenuated with antipyretic medication as a means to treat unpleasant symptoms of infectious diseases. We highlight a potentially important negative effect of fever suppression that becomes evident at the population level: reducing fever may increase transmission of associated infections. A higher transmission rate implies that a larger proportion of the population will be infected, so widespread antipyretic drug use is likely to lead to more illness and death than would be expected in a population that was not exposed to antipyretic pharmacotherapies. We estimate the magnitude of this effect for influenza and find it is significant, causing an increase of 4% in the expected number of cases and deaths [95% CI: 0.119–11%].

101 Americana Salon 4 Emotion II 11:30 Common knowledge and the self-conscious emotions Kyle Thomas, Steven Pinker (contact: [email protected]) The self-conscious emotions (pride, guilt, shame, embarrassment) evolved to regulate human social relationships. Though evolutionary psychologists typically focus on the problem of altruism in relationships, captured by the Prisoners’ Dilemma and similar games, we suggest that the self-conscious emotions are also sensitive to the problem of mutualism in relationships, captured by the Stag Hunt game. Mutualism is based on the logic of coordination, and game-theoretic models show that common knowledge (A knows that B knows that A knows that B knows…) has a privileged role in securing coordination. We present evidence that the self-conscious emotions are sensitive not only to audience members' knowledge of an emoter’s prior action but to common knowledge of the action: Shame, embarrassment, and so on are most acutely felt when the actor knows that everyone else knows that everyone else knows… about some faux pas. The results may explain why certain facial and bodily postures evolved to signal these emotions, and highlight the interaction between the incentive problems of altruistic cooperation and the epistemological problems of mutualistic coordination in human social life.

11:50 Towards an evolutionary psychology of attitudes: Affective representations moderate social emotions and behavior in Fiji Matthew Gervais, Daniel Fessler (contact: [email protected]) The attitude construct is foundational to social psychology, yet there remains no adaptationist rendering of attitudes to complement that for emotions. Here we develop and test a model that functionally renders attitudes vis-à-vis emotions in terms of their complementary design features and adaptive problems. Attitudes represent the fitness affordances of objects, and moderate emotions; emotions implement adaptive behavior, while updating attitudes in the common currency of affect. We present data supporting this model from mixed-methods fieldwork in rural Fijian villages. English and Fijian have a similar set of interpersonal attitude terms that go far beyond “liking” (e.g., “love,” “hate,” “respect,” “fear,” “contempt”). Fijian terms for putative attitudes and emotions have distinct pragmatic, phenomenological, and functional correlates. Interpersonal attitudes in Fiji adaptively moderate emotional reactions across social scenarios, and each attitude is emotionally pluripotent. Different interpersonal attitudes also predict different behaviors in three economic games with identifiable recipients.

12:10 Conceptual and empirical challenges to the “authentic” versus “hubristic” model of pride Colin Holbrook, Jared Piazza, Daniel Fessler (contact: [email protected]) An increasingly influential perspective posits that the emotion pride decomposes into two distinct facets characterized by distinct ways of appraising the causes of achievement. “Authentic Pride” (AP) ostensibly attributes success to one’s temporary effort, whereas “Hubristic Pride” (HP) purportedly attributes success to one’s permanent, intrinsic ability. In four studies, we present evidence which directly contradicts this model. In Studies 1a and 1b, perceptions of not genuinely meriting credit for successes mediated HP ratings, and in Study 3, HP scores correlated with perceptions of oneself as undeserving of credit for success. Across studies, HP was uncorrelated with causal attributions of success to effort, personal ability, permanent traits, or the self, whereas AP scores predicted attributions of success to effort, ability, permanent traits, and the self. Although these results are incompatible with the Authentic and Hubristic model of pride as previously formulated and measured, we advocate, on evolutionary grounds, for continued inquiry into the prospective two-facet structure of pride.

102 Poinciana 3/4 Symposium (cont.): Facing challenges and evolutionary happiness in Latin America Organizer: Jorge Yamamoto 11:30 Why and how local institutions weaken, fall and rise in the context of political violence Carlos Aramburu (contact: [email protected]) Accomarca is an Andean community of 150 quechua speaking families in Ayacucho, Peru, the department that suffered the most intense impact of terrorism in the 1980’s both from “Shining Path” as well as from the armed forces. As a result of a decade of terror, public institutions such as the local government, the health post, schools and local organizations disappeared. Today, this Andean community has revived having strong local authorities, 3 health facilities, 23 health agents, 4 water and sanitation groups, 4 schools and a new irrigation system. Our presentation document the fall and rise of local organizations through interviews with present and past authorities. Our main questions are ¿How did terrorism and repression destroyed local trust and both public and grass roots organizations? ¿ What were the factors and actors responsible for their revival? Our approach is based on political ethnography and stresses resilience of local groups and leaders.

11:50 Five clusters of values: Shades from altruists to cheaters Sebastian Wendorff (contact: [email protected]) Values is a central concept in social psychology for the analysis of reciprocal altruism. Cluster analysis of values can provide empirical groups of people according to altruistic – cheater continuum. An emic, inductive research was conducted to identify values clusters. From 250 open-ended interviews, categories for a values scale were extracted. This scale was applied to 500 participants in a representative sample of Lima, Peru. Results yielded 5 clusters: altruists, positive individualists, pragmatic collectivists, pragmatics, and cheaters. Results are discussed in terms of evolutionary and cultural issues.

12:10 Facing challenges and latin american happiness from an evolutionary perspective Jorge Yamamoto (contact: [email protected]) Happiness world surveys describe Latin America as the happiest region in the world. An inductive, qualitative and quantitative study identifies three confirmatory needs factors positively related to subjective well-being in Latin America: Optimistic adaptation, a Good place to live, and Raise a family. Results are discussed in terms that Latin America is a relatively unsure place to live, that resembles the ancestral challenges. The collectivistic interaction based on family, and close friends, is a main resource to face the challenges for survival and fitness. An Optimistic adaptation is a copying-trait like cultural style that helps to adapt to circumstances but take advantage when an opportunity arises. Differences between rural Andean, rural Amazonian, peri urban and urban environments are presented. Implications for development programs are discussed.

103 Friday, July 19

EARLY AFTERNOON SESSION

Americana Salon 1 Emotion III 4:20 Disgust sensitivity, personality, and evolutionary perspectives on individual differences Joshua Tybur (contact: [email protected]) Instruments designed to measure “disgust sensitivity” – that is, the degree to which individuals report being disgusted by objects, behaviors, or concepts that commonly elicit disgust – are widely used to test evolutionary hypotheses. However, understanding of the constructs that such instruments capture remains modest. In this talk, I focus on how relationships with basic dimensions of personality can inform how evolutionary psychologists understand and interpret disgust sensitivity. I review previously reported relationships between several disgust sensitivity instruments and measures of Five Factor Model dimensions, and I present new data on how the Three Domain Disgust Scale relates to the six-dimensional HEXACO PI-R in a large (N = 476), demographically diverse Dutch sample. I discuss how these new data can inform our understanding of disgust sensitivity, and how disgust sensitivity instruments can be used to test hypotheses concerning the fitness-relevant tradeoffs underlying variation in personality, especially those relevant to infectious disease.

4:40 Behavioral evidence that pathogen disgust functions as a contagion avoidance mechanism Corey Fincher, Amanda Hahn, Claire Fisher, Benedict Jones, Lisa DeBruine (contact: [email protected]) Using a key-press paradigm, we tested the proposal that pathogen disgust functions to reduce exposure to sources of infectious disease. We also examined whether participants with recent infections would be more motivated to reduce interactions with contagion cues. Participants were shown images of buildings, people brandishing guns, and people displaying cues of infectious disease. Participants could increase or decrease the viewing time of these images by repeatedly pressing designated keys on the computer keyboard. People reporting higher levels of pathogen disgust, but not sexual or moral disgust, were more willing to expend effort to remove images of infectious disease from the screen. By contrast with these findings for pathogen disgust, reported recent infections did not predict viewing time for infectious disease images. Together, these findings support the hypothesis that pathogen disgust functions to reduce exposure to sources of infectious disease but also suggest that the relationship between pathogen disgust and contagion avoidance is not driven by experience of recent infections.

5:00 Measuring “moral contagion”: Perceptions of moral character modulate physical distancing responses Hillary Lenfesty (contact: [email protected]) Widespread cultural beliefs and practices demonstrate that contagion concerns extend beyond the biological realm into the moral domain. The concept of moral contagion may be grounded in human strategies for avoiding disease-carrying individuals, but it remains unclear as to whether or not these concepts are simply metaphors of disease contagion. The present set of studies measured automatic physical distancing responses- behavior typical of perceived illness contagion- towards real moral agents. In both studies, participants engaged in a joint dummy task requiring physical contact with an anonymous partner’s hands following negative, neutral, or positive moral background information about their partner. In Studies 1 and 2, negative moral perceptions lessened participants’ duration of physical contact with their partner, while positive perceptions significantly increased it. In Study 2, moral information also modulated the amount of surface area of contact accordingly. These results reveal that moral qualities can activate genuine contagion concerns, and that concepts of positive moral contagion may play an important role in bringing and binding individuals together.

5:20 Infectious disease, values, IQ, and the wealth of nations Randy Thornhill, Corey Fincher (contact: [email protected]) The parasite-stress hypothesis of economics proposes that variation in infectious disease across regions causes variation in economic productivity by three proximate causes. 1) Infectious diseases cause morbidity, reducing people's capability to produce. 2) Parasite stress evokes people's values, which, in turn, cause regional economic parameters. E.g., as parasite stress increases, regions become increasingly collectivistic. Collectivism causes parochial economics, political corruption, autocratic governance, and reduced innovativeness and diffusion of innovations. These effects stifle economic productivity. In contrast, individualism causes willingness to transact with a diversity of people, creating broad economies and interregional sharing of ideas and products, increased innovativeness, governmental transparency, and democracy. These effects promote economic prosperity and equality. 3) Infectious disease limits cognitive ability, which reduces innovativeness and thus economic wellbeing in a region. We present evidence from cross-national and U.S. interstate analyses supporting the parasite-stress hypothesis of economics.

104 Americana Salon 2 Symposium: Strategic and cognitive differentiation and integration as a function of life history strategy Organizer: Aurelio José Figueredo 4:20 Multiple successful tests of the strategic differentiation-integration effort (SD-IE) hypothesis Aurelio José Figueredo, Michael A. Woodley, Kari Celeste Ross, Sacha D. Brown (contact: [email protected]) The Strategic Differentiation-Integration Effort (SD-IE) hypothesis predicts regulation by life history speed (K) of the magnitudes of the correlations among its components, such that higher-K individuals exhibit life history traits that are less correlated with each other (more conatively differentiated) than lower-K individuals, because strategic specialization with respect to various domain-specific resource allocations should permit resource polymorphism under conditions of elevated social competition. Applying the Continuous Parameter Estimation Method (CPEM; Gorsuch, 2005) to data from two college student convenience samples (one all-female and one mixed-sex) as well as two nationally-representative US population samples (MIDUS and NLSY), statistically significant SD-IE effects were found in the expected negative direction among most indicators of the lower-order slow life history factors (11/14 in the combined student sample; 13/14 in the MIDUS sample; 7/7 in the NLSY sample) and among all indicators of the single higher-order slow life history Super-K factor (3/3 in all samples tested).

4:40 Strategic allocation of cognitive abilities: A look at life history’s role in cognitive differentiation and integration Rafael A. Garcia, Tomas Cabeza de Baca, Christopher J. Wenner, Kari Celeste Ross, Sacha D. Brown, Aurelio José Figueredo (contact: [email protected]) Cognitive Differentiation-Integration Effort (CD-IE) hypothesis posits that slower life history individuals will strategically allocate effort among cognitive abilities; the result is diminished correlations among these traits. Data from three samples (two from a Southwestern university and one from a vocational training program) were used to test the integration of slower life history (K) with: executive functioning (EF), socially desirable responding (SDR), emotional intelligence (EI; sample 1), and the multidimensional work ethic profile (MWEP; samples 2 & 3), which are theoretically advantageous for implementing such slower strategies. Unit-weighted factors were constructed for each of these scales, and then Continuous Parameter Estimation Modeling (CPEM; Gorsuch, 2005) was applied to estimate the effect of the absolute level of K upon their bivariate correlations with K, which demonstrated that there was a differential allocation of cognitive resources depending on environmental demands.

5:00 Strategic differentiation-integration effort in the context of sexual strategies: A cross-national perspective Heitor Fernandes, Michael A. Woodley, Claudio Hutz, Daniel Kruger (contact: [email protected]) This cross-national study explored the generality of the Strategic Differentiation-Integration Effort hypothesis as it pertains to Sexual Strategies (SS). We hypothesized that a High-Order K Factor (HOKF) regulates the strength of the correlation among indicators of SS, such that individuals with higher K exhibit more weakly integrated strategies than those with lower K. Indicators of SS included Sociosexual behavior, desire, and attitudes; Attachment style; and Postcoital avoidance. These variables along with Mate value-self rated, reputation-maintenance emotions (variables correlated with K and SS indicators) and the Mini-K comprised HOKF. The Continuous Parameter Estimation Model was employed to test the hypothesis in American, Brazilian, and multi-national samples. All variables presented hypothesis-supportive correlations across all samples; except Sociosexual attitudes, which had partial corroboration. Effects were strongest in the multi-national sample, possibly due to a combination of population stratification, higher mean age (therefore higher K) and derestricted range. Relations with sexual orientation were also explored and are discussed.

5:20 Cognitive differentiation-integration effort in developmental perspective Michael A. Woodley, Curtis Dunkel, Aurelio José Figueredo (contact: [email protected]) We tested the change predicted by the Cognitive Differentiation-Integration (CD-IE) hypothesis in the strength of the correlation between general cognitive ability (g) and its component subtest scores in three different age cohorts of children (3- 4, 11, and 18) as a function of life history speed (K). Significant CD-IE effects were absent in the 3-4 year olds (mean β=.01). In the 11 year olds all CD-IE effects trended in the expected negative direction and most (6/11) were statistically significant (mean β=-.23). In the 18 year olds, all but one CD-IE effect trended as expected but only one was significant (mean β=-.12). Mean differences were significant when all age cohorts were compared, indicating that LH drives cognitive differentiation from infancy up to age 11. Between 11 and 18, there is modest ability de-differentiation with respect to LH. The method of correlated vectors indicated that between ages 3-4 and 11, the CD-IE effects exhibit an increasing affinity for more g-loaded subtests (r=.39 to .59); in the 18 year olds, the CD-IE effect loses affinity for g, dropping to .19.

105 Americana Salon 3 Cognition I 4:20 Back to the drawing board: Computational-evolutionary revisitations of some early work in psychology Jason Wilkes (contact: [email protected]) The ongoing fusion of adaptationist and computational methods is placing psychology on a new foundation. This approach allows one to revisit early work in psychology from a new perspective, in the hope of explaining results long known but not previously understood. The historically neglected half of probability theory consists of the development of principles for translating vague and qualitative prior information into quantitative prior probability distributions. At present, the two most powerful principles known for effecting this translation are (1) maximum information-theoretic entropy, and (2) the principle of group-invariant ignorance. It is shown that these two fundamental principles of inference, when combined, shed new light on classical conditioning phenomena (Wilkes & Gallistel, forthcoming), as well as the psychophysics of magnitude representation (Wilkes, in press). We discuss why this approach may allow the generation of new inferences from known psychophysical data, as well as hints suggesting a possible unity of certain low-level neural computations.

4:40 The ecological rationality of intertemporal choice in humans Evan Carter, Eric Pedersen, Michael McCullough (contact: [email protected]) Many contemporary social concerns (e.g., consumer debt, addiction, failure to save for retirement) can be viewed as problems of intertemporal choice, which humans are thought to solve poorly because of a preference for immediate gratification that reduces their long-term gain when choosing between immediate and future consequences (i.e., impulsive choice). Evidence from other species, however, suggests that impulsive choice is caused by a mismatch between the presentation of options in the laboratory and that of options in realistic settings (e.g., foraging). Here, we present evidence that humans are more likely to maximize long-term rates of gain when options are presented in a way that more closely simulates the real world (i.e., the more immediate option remains available during pursuit of the delayed option). Results from our experiment support the hypothesis that humans’ seemingly impulsive behavior may be caused by decision rules that maximize gain in the contexts within which they evolved.

5:00 A game of hide and seek: Expectations of clumpy resources influence hiding and searching patterns in a sequential multi-person game Andreas Wilke, Steven Minich, Megane Panis, Tom Langen, Peter Todd (contact: [email protected]) Animals use hoarding as a long-term strategy to ensure a food supply in times of shortage. But how do they promote the likelihood that they will be able to find those resources again, while minimizing the chance that others will find them? To reduce food cache loss from pilferage, scatter-hoarder bird species hyper-disperse multiple seed caches, positioning them further apart from each other than expected by chance. Here, we systematically look at human hiding and search patterns emerging from multiple goals. Subjects had to hide resources that other players would then seek (either in ways that would make the seeking easy or difficult), search for resources that others hid from them, and later relocate their own earlier hiding places. Results supported our predictions that subjects hide resources in clumpy resource patterns when they are collaborating with other players, but disperse resources when in competition.

5:20 Sequential decision making and illusionary pattern detection in gamblers Paige McCanney, Aisha Wood, Amanda Sherman, Benjamin Scheibehenne, Wolfgang Gaissmaier, Clark Barrett, Andreas Wilke (contact: [email protected]) In previous research, we investigated a widely-known and systematic irrationality in human cognition known as the hot hand phenomenon: the tendency to perceive streaks or clumps in sequences of events that are, in fact, random. In several papers, we proposed and found evidence supporting the hypothesis that the hot hand phenomenon is a universal aspect of human cognition, present across cultures, and that it may derive from our foraging past as an adaptation for seeking resource clumps or clusters in the environment. In the present research, we explored whether individuals who have a greater propensity towards hot hand and/or the gambler’s fallacy also show an increased propensity to gamble in computerized decision-making tasks. We collected additional measures of cognitive capacity and standardized screens of gambling history, as well as psychometric measures of risk-taking propensity. While prior studies have reported relationships between irrational beliefs and gambling by asking subjects about their beliefs, our methodology allows for the direct measurement of systematic judgment biases by analyzing subjects’ actual behavioral choices in sequential search tasks.

106 Americana Salon 4 Attractiveness I 4:20 Visual, olfactory, and vocal cues to women’s reproductive value Susanne Röder, Bernhard Fink (contact: [email protected]) Visual, olfactory and vocal cues may serve as indirect signals to women’s fertility. However, most of the studies in support of this assertion have been derived from the investigation of menstrual cycle related behavioural and/or sensorial changes of young adult women (and men’s perception of them). The present study investigated men’s perception of visual, olfactory and vocal cues in young girls, adult women and post-menopausal women. Facial photographs, body odours and voice recordings of young girls, adult women and peri-/post-menopausal women were collected and judged on attractiveness and femininity. Faces and voices (but not body odour) of young girls and adult women were perceived to be more attractive than those of peri- /post-menopausal women. Moreover, women’s chronological age predicted men’s perception of facial and vocal attractiveness and femininity. Our data suggest that facial and vocal cues (but not body odour) may be cues to female reproductive value.

4:40 You had me at hello: Acoustic correlates of thin slice judgments of women’s vocal attractiveness Greg Bryant, Martie Haselton, Elizabeth Pillsworth (contact: [email protected]) Past work has shown that youthful and feminine acoustic features of women’s voices are associated with judges’ ratings of voice attractiveness. However, little work has explored how women might alter their voices deliberately to signal these qualities. We collected two sets of vocal samples from 76 women. They produced introductory sentences (Hi, I’m a student at UCLA) in response to four different prompts that instructed them to say the sentence neutrally (baseline), friendly, signaling sexual interest toward a man, and trying to be attractive for male judges. We then extracted the “Hi” segment (mean length 462 ms) of the “baseline” and “trying to be attractive” samples from both sets of recordings (4 clips per woman) and played the segments for judges who rated them for attractiveness. We also analyzed the segments acoustically. Recordings of the women trying to be attractive were higher pitched, slower, and more breathy than baseline recordings, and they were rated as more attractive by judges. These results show that women can manipulate their attractiveness on command in a noticeable way, and judges can detect it with less than half a second of information.

5:00 Facial coloration and the behavioral immune system Benedict Jones, Amanda Hahn, Claire Fisher, Corey Fincher, Carmen Lefevre, Ross Whitehead, Michal Kandrik, David Perrett, Anthony Little, Craig Roberts, Lisa DeBruine (contact: [email protected]) Research linking variation in facial attractiveness judgments to concerns about infectious disease suggests that face preferences are a component of the behavioral immune system. However, these studies have typically focused on preferences for shape cues in faces or used stimuli in which shape and surface information were confounded. In the current research, we first show that aspects of facial coloration (red and yellow) are correlated with a composite measure of reported health and incidence of infectious disease (Study 1). Consistent with earlier work, we also show that manipulating these color characteristics in face images affects health perceptions (Study 2). We then show that exposing subjects to pathogen-related stimuli increases attraction to healthy facial coloration (Study 3). Finally, using a longitudinal design, we show that attraction to healthy facial coloration is generally stronger on days where subjects report greater germ aversion (Study 4). Together, these findings implicate germ aversion in attraction to healthy facial coloration, supporting the proposal that facial attractiveness judgments may be an important component of the behavioral immune system.

5:20 Predicting health from facial shape: A geometric morphometric modelling study Ian Stephen, Vivian Hiew (contact: [email protected]) Several aspects of facial appearance have been suggested to reflect health status including shape (Perrett et al, 1998), colour (Stephen et al, 2009,2011) and texture (Matts et al, 2007). While it is suggested that attractive appearance reflects health, few studies have identified connections between appearance and real health (Coetzee et al, 2009). We hypothesized that we would be able to statistically predict, both actual and perceived health from face shape. 100 students were photographed, and aspects of their real health - BMI, body fat, and blood pressure were measured. Faces were rated for apparent health of the images from part 1 on a 7-point scale. Geometric morphometric modelling (Scott et al, 2010) was used to predict health variables from the shape data. Face shape significantly predicted both actual and perceived health. Hence, face shape contains cues to real health that are detectable by observers. This technique has successfully predicted aspects of real health in a sample of university students, and confirms facial shape as important in people’s perceptions of health in others.

107 Poinciana 3/4 Cooperation VII 4:20 Natural recreation of a dictator game reveals no altruism Jeffrey Winking (contact: [email protected]) Economic experiments are increasingly being used in a number of research areas and are the major source of data guiding the debate surrounding the nature of human prosociality. The degree to which experiment behavior accurately reflects external behavior, however, has long been debated. A number of recent studies have revealed just how remarkably sensitive participants are to cues of a lack of anonymity. Similarly, others have suggested that the very structure of the experimental context induces participants to choose prosocial options. In order to truly create anonymous conditions and to eliminate the effects of experimental contexts, participants must not be aware of their participation. Here, I present the results of a natural- field Dictator Game in which participants are presented with a believable endowment and provided an opportunity to divide the endowment with a stranger without knowing that they are taking part in an experiment. No participants gave any portion of the endowment to the stranger. Baseline frequencies of prosocial behaviors exhibited under experimental contexts might therefore be substantially inflated compared to those exhibited under natural contexts.

4:40 Evolution of fairness in the one-shot anonymous Ultimatum Game Hisashi Ohtsuki, David Rand, Corina Tarnita, Martin Nowak (contact: [email protected]) In the Ultimatum Game, one player proposes a division of a sum of money between herself and a second player, who responds by either accepting or rejecting the proposal. The classical approach predicts responders should accept any non-zero offer and proposers should offer the smallest possible amount. Experiments instead show a preference for fairness: many responders reject low offers and many proposers make offers more generous than needed to avoid rejection. Here we show that a stochastic approach to evolutionary game theory can explain these observations. We assume that agents can make mistakes when judging the payoffs and strategies of others. Sometimes they imitate worse strategies, and sometimes they pick an entirely different strategy. In this setting, natural selection favors fairness. Across a range of parameters, the most common strategy matches the behavior observed experimentally, demanding between 25% and 40% as responder, and offering between 30% and 50% as proposer.

5:00 The evolution of merit by partner choice Stéphane Debove, Nicholas Baumard, Jean-Baptiste André (contact: [email protected]) Recent studies suggest that fairness can be understood as a psychological adaptation to solve the evolutionary challenge of sharing the benefits of cooperation. In a social environment where one can choose with whom to cooperate, dividing fairly is the best way to attract social partners without being overly generous (Baumard et al., 2013). However, how partner choice explains quantitative properties of fairness has not yet been thoroughly studied. Here, using stochastic individual-based simulations, we model the evolution of a division of a resource in a population where individuals differ with regard to three features: their bargaining power, their productivity, and the effort they put into cooperation. We show that when partner choice is efficient, evolution leads to divisions that have the most important features of human fairness. Productive and effortful individuals are rewarded in proportion to their contribution, whereas competitive individuals (with stronger bargaining power) receive no more benefits than others. Our results provide strong support for the idea that individual selection, with partner choice, can account for the evolution of human fairness.

5:20 Effect of limited resources on the dynamics of cooperation under indirect reciprocity Sayaka Ishihara, Hisashi Ohtsuki, Toshikazu Hasegawa (contact: [email protected]) Indirect reciprocity has been suggested as a mechanism sustaining cooperation in humans (Alexander, 1987). In previous game theoretic models of cooperation via indirect reciprocity, utility is considered, but limited resources are not (Nowak & Sigmund, 1998; Panchanathan & Boyd, 2004). Cooperation increases the total utility of agents, but resource limitations are not considered. In reality, however, cooperation is often influenced by resource constraints. For example, willing participants can only cooperate if in possession of sufficient resources. Therefore, investigation of cooperation in terms of fixed resources is required. In our research, we introduced resource limitations into a model of indirect reciprocity developed by Ohtsuki & Iwasa (2004), who exhaustively investigated the ability of various transaction strategies to sustain cooperation under different global norms for determining agent reputation. We conducted a series of computer simulations to examine the effect of resource flows among agents across multiple transactions on the success of different cooperative strategies.

108 Friday, July 19

LATE AFTERNOON SESSION

Americana Salon 1 Emotion IV 5:50 “Hows” and “whats” inform the “whys”: Evolution, development, and the emergence of disgust Joshua Rottman, Peter Blake (contact: [email protected]) Evolutionary developmental psychology has typically approached the integration of phylogenetic and ontogenetic perspectives by using the ultimate “whys” of development to elucidate the proximate “hows” and “whats” (Bjorklund and Pellegrini, 2000). Here, we explain how knowledge about the developmental origins of a psychological trait can be used to evaluate theoretical claims about its evolved function. In order to illustrate this approach, we focus on the emotion of disgust. Disgust is commonly thought to be an adaptation for avoiding the ingestion of pathogens (Rozin, Haidt, and McCauley, 2008). Given this claim, we should expect its developmental emergence when humans are most vulnerable to ingesting pathogens, during the immediate post-weaning period at about 3 years of age (Dobson and Carper, 1996). Despite strong selective pressure at this point in development (high mortality), research has shown that the experience of disgust and the recognition of the “disgust face” appear much later, around 6-7 years of age (Rozin and Fallon, 1987; Widen and Russell, 2013). Given the late developmental appearance of disgust, we re-evaluate claims about its adaptive role.

6:10 Unfamiliar religious groups are perceived as more different to people who are disgusted by pathogens (but not by sex or morality) Scott Reid, Grace Anderson, Jinguang Zhang, Jessica Gasiorek, Marko Dragojevic, Susana Peinado, Becky Robinson (contact: [email protected]) The parasite-stress theory of sociality assumes that pathogen-host arms races drive geographically localized immunities in humans, and that humans possess a “behavioral immune system” that enables them to avoid outgroup members who possess novel pathogens. We hypothesized that perceptual intergroup difference facilitates group tracking and outgroup avoidance, and that the extent of perceived intergroup differences should be calibrated to the potential costs of infection. We predicted that increases in individual disgust due to pathogens would positively correlate with perceived differences between one’s religious ingroup and unfamiliar religious outgroups. Studies 1a and 1b confirmed this hypothesis, and showed no effects of sexual or moral disgust. Study 2 replicated the positive correlation between pathogen disgust and perceived difference from unfamiliar religions, but this effect was limited to religious participants who were exposed to a pathogen (but not a violence) prime.

6:30 Understanding sexual prejudices: Avoiding threats of unwanted sexual interest? Angela Pirlott, Steven Neuberg (contact: [email protected]) We propose that heterosexuals’ sexual prejudices against non-heterosexuals partially arise from a concern that certain non- heterosexual groups direct unwanted sexual interest toward them. Unwanted sexual interest can threaten sexual autonomy by creating coercive sexual situations or by creating doubt about one’s sexual orientation. Consistent with sex differences in obligatory parental investment and consequent sexual strategies, Study 1 demonstrated that heterosexual women believe that bisexual men, bisexual women, and lesbians (but not gay men) threaten unwanted sexual interest, whereas heterosexual men believe that bisexual and gay men (but not bisexual women or lesbians) threaten unwanted sexual interest. Study 2 revealed nuanced patterns of prejudice mirroring Study 1’s pattern of perceived unwanted sexual interest, and Study 3 demonstrated that these perceptions statistically mediated the group-prejudice relationship. In contrast, traditional theoretical approaches to understanding sexual prejudices—e.g., the simple ingroup-outgroup heterosexism, gender-role violation, and sexual identity threat positions—cannot account for the observed pattern of findings.

109 Americana Salon 2 Individual Differences I 5:50 The mating/parenting trade-off: Short-term mating orientation and mate value predict less nurturing emotional responses toward infants Alec T. Beall, Mark Schaller (contact: [email protected]) There is a trade-off between investment in mating effort versus parenting effort (see Gangestad & Simpson, 2000). In addition to its implications for psychological correlates of life-history variables (e.g., sex differences and parent/non-parent differences in responses to potential mates and toward children), this trade-off may manifest more broadly at the level of individual differences in emotional responses: Motivation and ability to engage in short-term mating behavior may inhibit a nurturing emotional response ("tenderness") toward infants. To test this hypothesis, a diverse sample of North American adults (N = 819) completed measures assessing short term mating orientation (STMO), self-perceived mate value, dispositional tenderness, and the intensity of emotional responses to photographs of babies. Results revealed that both STMO and mate value were significantly inversely correlated with dispositional tenderness; these significant effects remained even when controlling for sex and parenthood. Weaker inverse effects were found on the intensity of nurturing emotional responses to babies, and these effects were mediated by dispositional tenderness.

6:10 Exploring sex differences in color preference using online resources Casey McGlasson, Jared Lorince, David Crandall, Peter Todd (contact: [email protected]) Previous color preference studies have been various in their methods and results. Researchers disagree about the causes of color preferences, as well as the existence of differences in color preference between males and females. Past researchers, such as Hurlbert and Ling (2007), have suggested evolutionary explanations for sex differences in color preference. We evaluate the claim that such sex differences exist using a novel implicit method and explore the possibility of adaptive values associated with sex-specific color preferences. We propose a data-mining approach using a dataset of more than 100 million photographs from Flickr, an online photo-sharing site. Using this method, we find strong sex differences for the predominant red and blue hues. We further explore two alternative hypotheses for this sex difference. First we assess the relationship between color preferences and color vision deficits using the online crowd-sourcing marketplace, Mechanical Turk. Finally, we compare the color spectra of manually taken photographs with the natural spectra captured by lifelogging cameras to assess the degree to which hue distributions of online photos reflect aesthetic choices.

6:30 Sex differences in conformity: Confidence as a proximate psychological mechanism Catharine Cross, Gillian Brown, Thomas Morgan, Kevin Laland (contact: [email protected]) Aims: To examine confidence as a proximate psychological mechanism for sex differences in conformity. Methods: Participants (64 men, 104 women) solved puzzles (mental rotation or alphabet transformation) and reported their confidence in each answer. They then saw genuine decisions of previous participants and were asked to answer again. Using a hierarchical Bayesian path model, we used participant sex, confidence, and accuracy to predict the probability that the participant would switch their answer to match the majority. Results: Across both tasks, confidence had a large effect on social information use, i.e. participants used a ‘copy-when-uncertain’ strategy. As confidence reflected initial accuracy, this strategy increased the number of correct answers given. Women reported lower confidence than men (independent of accuracy), which in turn increased their probability of using social information. Conclusions: Both sexes use a ‘copy-when-uncertain’ strategy, but women are more likely to lack confidence in their answers. This suggests that sex differences in conformity can be explained, at least in part, by sex differences in confidence.

110 Americana Salon 3 Cognition II 5:50 Power on my side: A coalitional psychology approach to the vicarious experience of power Jennifer Sheehy-Skeffington, James Sidanius (contact: [email protected]) We bring a coalitional psychology perspective to the literature on social power. Across six experiments with a range of social groups, participants reported feeling more approach-oriented when they were merely exposed to a story in which an ingroup member gained power. This effect was enhanced among those who highly identified with the group in question, but went away when the character described was a member of another social group. Highlighting the role of alliance-related cues, we show that the sensitivity of approach orientation to the power of ingroup others is not due to liking or similarity, and is conditional on the loyalty of the ingroup character. The last two experiments present evidence that increases in approach orientation occur even when participants are exposed to the power of others implicitly, suggestive of the intuitive triggering of a set of social cognitive mechanisms evolved to guide behavioral orientations in a coalitional context.

6:10 Does valence modulate source memory? Laurence Fiddick, David Mitchell (contact: [email protected]) Bell and Buchner (2010) report that people display enhanced memory for a person's disgusting actions as opposed to pleasant actions. They interpret this finding as evidence against proposals that similar enhanced memory for cheating behavior requires a special-purpose cheater memory. Instead, they suggest that people have a more general tendency to remember threatening actions. However, disgusting actions are threatening to others via contagion, making cheating and disgusting actions social threats. Conversely, people who endanger themselves by breaking precautionary rules do not necessarily threaten others. We investigated whether people also show enhanced long-term memory (over 1-, 2-, and 4-week delays) for non-social threats (contrasted with memory for cheating) and failed to find support for memory for threatening actions more generally. Instead, long-term memory for actions seems to be most sensitive social threats, in this case cheating.

111 Americana Salon 4 Attractiveness II 5:50 Genetic analysis of male and female twins does not support ‘indirect benefits’ account of masculine male face shape Brendan Zietsch, Anthony Lee, Dorian Mitchem, Margaret Wright, Nicholas Martin, Matthew Keller (contact: [email protected]) For women, choosing a facially masculine man as a mate is thought to confer genetic benefits to offspring. This assumes that variation in facial masculinity is due to genetic variation. It also assumes that genetic factors that increase male facial masculinity do not increase facial masculinity in female relatives. Using geometric morphometrics, we quantified the configuration of facial landmarks on photographs of identical and nonidentical twins, and their siblings. Discriminant function analysis was used to determine the linear combination of shape variables that differs most between the sexes; participants’ score on this discriminant function captures their facial masculinity. Using biometrical modelling, we show that much of the variation in male and female facial masculinity is genetic. However, we also show that masculinity of male faces is unrelated to their attractiveness and that facially masculine males tend to have facially masculine, less-attractive sisters. These latter findings challenge the idea that facially masculine men provide net genetic benefits to offspring, and call into question this popular theoretical framework.

6:10 On the modulatory effects of cortisol on associations of testosterone with male attractiveness, facial masculinity and health Nicholas Grebe, Steven Gangestad (contact: [email protected]) The immunocompetence handicap hypothesis states that testosterone (T) suppresses immune function and accordingly, through sexual selection for a handicap, T-facilitated traits honestly signal male immunocompetence. The stress-linked immunocompetence handicap hypothesis (SLIHH) argues that glucocorticoids (e.g., cortisol, C) play a modulatory role. Rantala et al. (2012) found T x C interactions on immune function (production of antibodies after vaccination) and male attractiveness; T had more potent positive associations when C was low (cf. Moore et al. 2011, who argued for opposite T x C effects). In three samples of U.S. men (total N > 220), we examined T x C interactive effects on attractiveness, facial masculinity, and health. In specific analyses, both positive and negative T x C interactions emerged, but none were robust overall. We discuss these mixed findings within a life history framework, within which T and C each modulate allocation of energetic and other resources to forms of effort.

6:30 Cross-cultural comparison of female perception of male dance movements Bernhard Fink, Bettina Weege, Nick Neave, Bettina Ried, Olival C do Lago (contact: [email protected]) The majority of studies on human physical appearance within the evolutionary psychology framework have focused on static two-dimensional representations of facial and body morphology. While such experiments are useful for testing people’s preferences and reactions to even subtle changes in physical features, there is the inherent limitation with regard to the ecological validity of these types of stimuli. Recent research on female perceptions of male body movements suggests that females derive similar cues of male ‘quality’ from movement as from faces and bodies. We report data on Brazilian and German women’s perception of British men’s dance movements. Eighty British men, all non-professional dancers, were recorded, using 3D optical motion-capture technology and women judged virtual characters (avatars) for perceived attractiveness. Zero-order correlation statistics revealed a significant positive association of Brazilian and German females’ assessments of British men’s dance attractiveness. We interpret this as preliminary evidence for cross-cultural consistency of women’s perceptions of men’s dance movements.

112 Poinciana 3/4 Life History III 5:50 The effects of early childhood environmental uncertainties on adolescents’ risk taking attitude and behavior: A life history analysis Jing Wu, Lei Chang (contact: [email protected]) This study investigated the association between a series of early childhood environmental uncertainties and life history tradeoff strategies of adolescence. Based on 620 junior middle school students in rural China, early childhood environmental uncertainties, including disasters and accidents, death of family members, parental especially paternal absence, and family relocation, were associated with fast life history strategies including early onset of puberty especially for girls, high impulsivity, short future orientation, low risk-taking perception, and high risk-taking tendency and behavior. These early life uncertainties happening before rather than after school age (approximately 7 years old) were particularly strongly associated with fast life history strategies. Future orientation also mediated some of the relations between early life uncertainties before school age and risk taking behavior during adolescence. These findings provide an evolutionary explanation of adolescents’ risk taking tendency as an adaptive strategy to race with environmental uncertainties.

6:10 Infant and child death in the human environment of evolutionary adaptation Jeremy Atkinson, Anthony Volk (contact: [email protected]) The precise quantitative nature of the Environment of Evolutionary Adaptedness (EEA) is difficult to reconstruct. The EEA represents a multitude of geographic and temporal environments, of which a large number often need to be surveyed in order to draw sound conclusions. We examine a large number of both hunter-gatherer (N = 20) and historical (N = 43) infant and child mortality rates to generate a reliable quantitative estimate of their levels in the EEA. Using data drawn from a wide range of geographic locations, cultures, and times, we estimate that approximately 27% of infants failed to survive their first year of life, while approximately 47.5% of children failed to survive to puberty in the EEA. These rates represent a serious selective pressure faced by humanity that may be underappreciated by many evolutionary psychologists. Additionally, a cross-species comparison found that human rates are roughly equivalent to Old World monkeys, higher than orangutan or bonobo rates and potentially higher than those of chimpanzees and gorillas. These findings are briefly discussed in relation to life history theory and evolved adaptations designed to lower high childhood mortality.

6:30 The influence of past and present living environments: Are current risk assessments shaped by the dangers of our childhood environment? Amanda Sherman, Steven Minich, Tom Langen, Joseph Skufca, Andreas Wilke (contact: [email protected]) Life-history research indicates that humans internalize environmental cues of mortality risk at an early age, which influences subsequent risk-perception and behavior. Therefore, an individual's current risk-assessment may be viewed as an adaptive response to the challenges present within his or her early local environment. Here we examined the effects of several ecological factors (e.g., prevalence of crime, registered sex offenders) and life-history variables (e.g., sex, sibship size, early living arrangement) on an individual's perception of risk within their local living-environment. Participants provided three zip codes corresponding to their early, adolescent, and adult residences, enabling us to compare their subjective ratings of danger with the federally reported crime statistics of that location. Our results indicate that an individual’s early living arrangement, sibship size, and the early prevalence of registered sex-offenders indeed influence their risk-perception in adulthood. Our data provides support that early ecological factors signaling environmental danger have an influence on the mechanisms by which we assess risk within our current local environment.

113 Saturday, July 20

EARLY MORNING SESSION

Americana Salon 1 Cognition III 10:20 Effects of foraging related stimuli on object location memory and perceptual search in the hunter-gatherer theory Espen Sjoberg, Geoff Cole, Luke Cannon (contact: [email protected]) Hunter-gatherer theory suggests that women may possess an innate mechanism for fruit stimuli due to their gathering role in early human settlements, while for men an innate mechanism for animal stimuli have evolved due to game hunting. Experiment 1 was an object location task with stimuli manipulated to consist of fruit, animals or neutral objects. It was found that women perform higher than men with neutral stimuli, but this difference was abolished with fruit and animal stimuli. In Experiment 2 participants saw 20-item arrays of photos and were asked to identify a fruit or animal in the array as fast as possible. No sex differences were observed. Results show only partial support for the hunter-gatherer theory. We suggest that fruit and animals carry equal evolutionary weight where any mechanism is not related to foraging tasks, but instead to an importance for both sexes to obtain both types of nutrition.

10:40 Attentional basis of deontic reasoning in 3-5 year-old children: A test of social-contract and hazard- management theories Patrick Sellers II, Kayla Causey, David Bjorklund (contact: [email protected]) Social contract theory suggests that children and adults use deontic reasoning more efficiently in a social context (Cosmides & Tooby, 1992; Harris & Nunez, 1996). Deontic reasoning may be divided into at least two domain-specific areas of reasoning, social contracts and precautionary reasoning (Fiddick, 2004). Participants aged 3-5 hear four counterbalanced fictional stories regarding a fictional child, two including social obligations and two including precautionary rules. One story from each condition is obligatory, the other descriptive and non-obligatory, giving four total story conditions: Precautionary, Precautionary Descriptive, Social, and Social Descriptive. A change blindness paradigm assesses the subtle differences in children’s attention to information in scenes depicting social obligation or precautionary rule violations. A significant Rule Type X Scene interaction exists (F=6.903, p<.001), with accuracy increasing in scenes depicting a child meeting the condition rule when the rule is arbitrary (Rule Type 2). When the rule invokes safety as a reason for adherence (Rule Type 1), children have greater accuracy in change-detection for scenes depicting rule violations.

11:00 Powerful poses: Not necessary and not sufficient to produce feelings of power Melissa McDonald, Joseph Cesario (contact: [email protected]) Recent research on embodied cognition suggests a direct, unmediated link, between bodily positions and psychological states. From this perspective, holding an expansive bodily position directly causes the psychological feeling of power. Here, we suggest instead that bodily positions provide only one source of information to the brain, namely, what types of action are possible given the bodily position. Given that one of the primary functions of the brain is to prepare the body for effective action, another essential source of information is the immediate context. We describe two studies demonstrating that the association between an expansive bodily position and the expression of power depends on features of the immediate context. These features include (1) whether the positions have meaning as dominance and submissiveness without the presence of other individuals, and (2) whether roles (context) provide more useful information about action possibility than body position. Results are discussed within an evolutionary and social cognitive perspective.

114 Americana Salon 2 Culture II 10:20 Class conflict and conciliation in evolutionary perspective: The German case, 1900 to 2000 David Meskill (contact: [email protected]) After World War II, the hostility and mistrust between the working class and bourgeoisie in many western countries rapidly dissipated, paving the way for broadly middle-class societies and domestic political stability. These developments offer the opportunity to study the conditions under which populations remain divided into hostile subgroups as well as those under which such groups merge. In the first section of the paper, I will draw on psychology, game theory, and evolutionary studies in order to produce a theory of large-scale group formation. In the second section, I turn to Germany as a case study, developing several quantitative measures to evaluate Germans’ changing sense of identity and group-affiliation. In the final section, I try to correlate changes in Germans' sense of identity with economic, political, technological, and cultural factors.

10:40 Parsing within-group determinants of fertility decline in two horticulturalist populations Anne Pisor (contact: [email protected]) Previous research indicates that increased market integration (MI) predicts the third stage of demographic transition, fertility decline. The Tucupeños of Bolivia appear to be both more market integrated and farther along the trajectory of fertility decline than the Mosetenes of Bolivia. This pattern can be parsed however: controlling for age and group membership, household MI and income interact to positively predict number of children. Higher levels of generalized trust and increased participation in hunting, a traditional activity, positively predict number of children independently of household MI and income. This suggests that, in these populations, 1) MI has a complex relationship with number of children, 2) engagement in traditional activities (lower acculturation) predicts more children, and 3) low generalized trust predicts fewer children. The latter finding is consistent with the idea that exposure to a larger social world may allow social transmission of low fertility norms while also leading to a drop in levels of generalized trust. The importance of considering MI separately from social world size and acculturation will be discussed.

11:00 An exploration of exploitation: Children’s religious acquisition Viviana Weeks-Shackelford, Todd Shackelford, Yael Sela, Alyse Ehrke, John Arvanitis (contact: [email protected]) Research on children’s acquisition of religious beliefs has generated conflicting results. Some research suggests that children are predisposed to invoke religious explanations for some events, but that these explanations are often displaced as they age and are exposed to non-religious explanations. Other research suggests that children do not naturally invoke religious explanations for events, but are instead taught these explanations by parents and peers. The current research aims to identify the psychological processes by which religion is acquired. We asked participants to provide retrospective accounts, from childhood to the present, of the ways in which parents and peers affected their religious beliefs. Discussion addresses the hypothesis that children acquire religious beliefs by parental and peer exploitation of children’s evolved psychology.

115 Americana Salon 3 Symposium: Evolutionary analyses of crime and punishment Organizers: David Buss, Vibeke Ottesen 10:20 The evolutionary psychology of crime David Buss (contact: [email protected]) Crimes are typically exploitative strategies that inflict costs on victims ranging from the loss of reproductively-relevant resources (theft) to the loss of life and with it all future opportunities to influence direct and indirect reproduction (murder). Reducing crime remains a high priority in most societies. Success hinges in part on correctly identifying its causes. This talk focuses on key conceptual issues in the evolutionary analysis of crime. The most central ones center on (1) whether humans have evolved specialized adaptations for committing crimes, (2) whether criminal behavior instead is best understood as a byproduct of other adaptations, (3) the personal and social contexts that trigger the implementation criminal exploitatitve strategies, and (4) the predictable contexts that reduce the likelihood of exploitative strategies. This talk highlights empirial evidence from studies of stalking, intimate partner violence, and homicide relevant to a deeper understanding of the evolutionary psychology of crime.

10:40 Adaptations and nonadaptations to violence & nonviolence Steven Pinker (contact: [email protected]) The historical decline of violence poses two challenges to our understanding: (1) the violence; (2) the decline. I propose five psychological mechanisms that can cause violence (rage, dominance, revenge, exploitation, and ideology) and four that can reduce it (self-control, sympathy, the moral sense, and reason). Secular changes may be explained as an interaction between broad historical forces and these psychological mechanisms.

11:00 Is it really inequality that drives variability in homicide rates? Martin Daly (contact: [email protected]) Decades of research have implicated income inequality as a strong correlate of homicide rates both within and between nations. These results are readily interpreted in terms of variably intense male competition for the means of reproduction. However, efforts to deny a causal impact of inequality on homicide are unrelenting. Recently, criminologist William Pridemore has claimed that poverty (“absolute deprivation”) is inadequately controlled in cross-national studies, and when it is properly specified, effects of inequality (”relative deprivation”) evaporate. In fact, it is Pridemore who operationalizes absolute versus relative deprivation inappropriately, and his argument is without merit. Inequitable access to resources still rules as the dominant source of homicide rate variability.

116 Americana Salon 4 Individual Differences II 10:20 Masters track participation in U.S. reveals a stable sex difference in competitiveness Robert Deaner, Vittorio Adonna, Michael Mead (contact: [email protected]) Men are more likely than women to engage in direct competition, but it is unclear if this reflects social structural conditions or evolved predispositions. These theories can be addressed by testing if the sex difference in sports competitiveness has decreased over time in the U.S., a society where social roles have converged. Study 1 assessed participation and performances by masters runners (40-74 years) at road races and track meets. Fast performances (relative to age-specific, sex-specific standards) occurred twenty times more often at track meets than at road races, and men participated much more than women at track meets but not at road races. Thus, track meet participation is a valid indicator of competitiveness. Study 2 used data from national championship track meets and yearly rankings lists to test whether the sex difference in masters participation decreased from 1988 to 2012. Women comprised 25% of finishers across all years. The sex difference decreased initially, but there was no evidence of change since the late 1990s. Therefore, the sex difference in competitiveness partly reflects evolved predispositions.

10:40 Broad face co-occurs with ankle morphology good for speedy sprinting and efficiency in long-distance running Gordon Bear, Jeremy Atkinson, Leslie Migliaccio, Jovan Naidoo (contact: [email protected]) The anatomy of the ankle controls the efficiency of long-distance running, as measured by oxygen consumed per kilogram of body mass per kilometer per hour (Scholz, Bobbert, van Soest, Clark, & van Heerden, 2008). Because plausible speculation posits the evolution of adaptations for running down prey (e.g., the hairlessness and perspiration glands that minimize overheating; Liebeman, Bramble, Raichlen, & Shea, 2009), we measured ankle morphology in two samples of young men. Those with broad faces proved to have ankles in which the moment arm of the Achilles tendon was short and thus conducive to efficient long-distance running. The ratio of facial width to facial height, a marker of pubertal masculinization, explained over 40% of the variance in the moment arm, even after controlling for the man’s stature. The same kind of ankle also appears to promote sprinting (Baxter, Novack, van Werkhoven, Pennell, & Piazza, 2012; Lee & Piazza, 2009). Perhaps then it is general athleticism in locomotion that is augmented by pubertal androgens through their influence on the morphology of the foot.

11:00 Navigational skills and multisensory calibration reflect individual differences in environmental distance perception Chela Willey, Russell Jackson (contact: [email protected]) Visual, vestibular and proprioceptive perceptual integration is essential for navigation of the environment and has evolved in light of selection pressures, such falling risk. However, large individual differences persist in perception and navigation of the environment. Differences found in these dimensions may reflect a perceptual weighting mechanism that is based upon the relative reliabilities of perceptual cues in order to navigate. We investigated the role of individual differences in the visual- vestibular system and how they may reflect distance perception of evolutionary relevant environments. Data suggest those individuals who are most visually oriented tend to have greater postural variability larger estimates of vertical surfaces than those least visually oriented. Results suggest that individual differences in perception may reflect navigational capacity. Our data hold implications in the coevolution of oculo-motor mechanisms and the fear of falling.

117 Poinciana 3/4 Phylogenetics 10:20 Food sharing and reciprocal altruism in humans and other primates: A phylogenetic meta-analysis Adrian Jaeggi, Michael Gurven (contact: [email protected]) Reciprocal altruism plays an important role in the evolution of cooperation. In particular, reciprocal food sharing allows human foragers to thrive in a risky foraging niche and primates may trade food for other commodities such as grooming or support. However, skepticism about reciprocal sharing prevails, particularly questioning the necessary conditions of producer control and contingency. Here we test whether giving food is positively correlated with receiving food or other commodities using meta-analyses. In 14 quantitative studies on foragers and 12 on primates with a total of 67 independent study units we found an overall weighted effect size of r=0.18. The effect size was similar for humans and primates, especially when commodities other than food were considered. After controlling for kinship, phylogeny, publication bias and other factors the correlations decreased but remained significantly positive. Having thus established a statistical contingency between giving and receiving, we discuss how this may be achieved proximately.

10:40 Detailed reconstruction of ancestral human and hominid behaviors using phylogenetic comparative methods Pavel Duda, Jan Zrzavý (contact: [email protected]) The origin of fundamental behavioral differences between humans and our closest living relatives is one of the central issues of evolutionary anthropology. Behavioral data on living great apes are essential for inferring the ancestral behaviors, which should be reconstructed trait by trait, using multispecies comparison and formal phylogenetic methods. By performing series of optimizations of 65 selected behavioral and life history characters for all extant great ape species we reconstructed unique suites of behaviors of last common ancestors in hominid lineage and assigned the origin of species-specific behaviors to individual nodes of the phylogenetic tree. The results suggest that while many fundamental behavioral and life history attributes of great apes and humans are ancient, possibly inherited from the common ancestor of all hominids, substantial proportion of extant species behaviors represents unique apomorphies or homoplasies. All great ape species are derived, relative to their common ancestors, and none of them alone represents an ideal proxy for the latter.

11:00 Do metabolic tradeoffs explain why humans have exceptionally large brains? Testing the expensive tissue hypothesis using phylogenetic analysis Amy Boddy, Athena Aktipis, Chet Sherwood, Lawrence Grossman, Derek Wildman (contact: [email protected]) Humans are unique in their exceptionally large brain mass relative to their body mass. A variety of hypotheses have been proposed to explain the evolution of large brains in Homo but not in other primates, including the social brain hypothesis, the expensive tissue hypothesis, and the sexual selection hypothesis. In this study, we used phylogenetic techniques to test the viability of the expensive tissue hypothesis, which states that reductions in other energetically expensive organs allow for reallocation of energy to the brain. Brain tissue is metabolically expensive, accounting for 20% of total metabolism in humans. We collected absolute brain and body mass from published literature from over 20 orders of Mammalia, represented by 630 species, calculated relative brain size and reconstructed the ancestral states. We determined there was a significant change in brain size along the anthropoid primate lineage. We found both brain expansion and reduction events in primates. These data support the Expensive Tissue Hypothesis, whereas folivores (i.e. colobine monkey), with an enlarged large intestine demonstrated a brain reduction event.

118 Saturday, July 20

LATE MORNING SESSION

Americana Salon 1 Symposium: Women’s sexual behavior: Causes, constraints, and context Organizer: Kristina Durante 11:30 The effects of paternal disengagement cues on women's sexual thoughts and perceptions Danielle DelPriore, Sarah Hill (contact: [email protected]) Previous research has demonstrated a robust association between father absence and daughters’ increased promiscuity and sexual risk taking. However, few studies have examined the causal impact that paternal disengagement cues exert on women’s sexual psychology. In a series of experiments, women described a time their biological father was physically or psychologically absent for an important life event (or a control prime) and then responded to measures assessing their sexual thoughts and perceptions. Our first experiment revealed that women primed with paternal disengagement cues demonstrated greater activation of sexual thoughts on a word stem task relative to women in the control condition. Our second experiment demonstrated that women primed with paternal disengagement perceived greater sexual intent in men’s actions and faces relative to women in the control condition. Taken together, these results suggest that greater accessibility of sexual cognitions may contribute to the reliably observed association between father absence and daughters’ increased sexual promiscuity and risk taking.

11:50 Fertile and flirty: Ovulation changes women’s behavior toward men Stephanie Cantu, Jeffry Simpson, Vladas Griskevicius, Yanna Weisberg, Kristina Durante, Daniel Beal (contact: [email protected]) Past research shows that men respond to women differently depending on where women are in their ovulatory cycle. But what might lead men to treat ovulating women differently? We propose that the ovulatory cycle alters women’s flirting behavior. We tested this hypothesis in a carefully controlled experiment, in which women interacted with different types of men at different points in their cycle. Findings revealed that ovulating women reported more interest in men who had markers of genetic fitness as short-term mates, but not as long-term mates. Furthermore, behavioral ratings of the interactions indicated that women displayed more flirting behaviors when they were at high versus low fertility. Importantly, ovulating women flirted more only when they interacted with men who had genetic fitness markers, but not with other men. In summary, fertility not only alters women’s behavior; it does so in a context-dependent way that follows adaptive logic.

12:10 The fluctuating female vote: Politics, religion, and the ovulatory cycle Kristina Durante, Ashley Rae, Vladas Griskevicius (contact: [email protected]) Each month many women experience an ovulatory cycle that regulates fertility. Whereas research finds that this cycle influences women’s mating preferences, we propose that it might also change women’s political and religious views. Building on theory suggesting that political and religious orientation are linked to reproductive goals, we tested how fertility influenced women’s politics, religiosity, and voting in the 2012 U.S. presidential election. In two studies with large and diverse samples, ovulation had drastically different effects on single versus married women. Ovulation led single women to become more liberal, less religious, and more likely to vote for Barack Obama. In contrast, ovulation led married women to become more conservative, more religious, and more likely to vote for Mitt Romney. In addition, ovulatory-induced changes in political orientation mediated women’s voting behavior. Overall, the ovulatory cycle not only influences women’s politics, but appears to do so differently for single versus married women.

119 Americana Salon 2 Culture III 11:30 Cumulative culture in the laboratory: You need more models, if the task is hard Michael Muthukrishna, Ben Shulman, Vlad Vasilescu, Joseph Henrich (contact: [email protected]) Previous laboratory social transmission experiments on cumulative culture failed to show any effect of larger cohort size (Caldwell & Millen, 2009, 2010). These results contradict formal models of cumulative cultural evolution, which illustrate the importance of multiple skilled models (Henrich, 2004). We tested these findings in two social transmission experiments using more complex tasks: photo editing (study 1) and knot tying (study 2). In study 1, participants were given no training in photo editing. In study 2, participants were trained in tying a series of knots. Over ten generations, compared to one model, participants who had access to five models showed larger improvements (study 1) and less loss of expertise (study 2). These results indicate that population size and consequent increases in the number of models for social learning can increase cumulative culture and reduce maladaptive losses for complex culture.

11:50 Stick to the script: The effect of witnessing multiple actors on children’s imitation Christine Legare (contact: [email protected]) What kinds of cues increase high fidelity cultural transmission in early childhood? The effects of multiple models and verbal framing on imitation were examined in preschool children (N = 192, 3-6-year- olds). Each participant was presented with one of six possible combinations of type of modeling and verbal frame. The type of modeling involved: (i) a single actor, (ii) two actors presented successively, or (iii) two actors presented synchronously. The verbal frame preceding a demonstration emphasized either (i) the instrumental outcome of the actions or (ii) their conventionality. Imitative fidelity was highest after synchronous models and lowest after one model, and higher after the conventional than the instrumental frame. Children also provided more conventional explanations for their actions after viewing the synchronous models and following the conventional frame. The results indicate that children’s stance toward imitation depends on the number of actors and the way the actions are framed.

12:10 Cultural evolution and model-based biases: Reading behavioral cues of performance Helen Wasielewski (contact: [email protected]) Humans acquire complex bodies of knowledge through social learning. The ubiquity of social learning across animal taxa suggests that it has an adaptive benefit, yet theoretical work indicates that social learning should not be deployed indiscriminately. Rather, learners should adopt the best possible solution by evaluating the payoff of modeled solutions, either directly or by proxy through characteristics of available models. Much of the existing experimental work on cultural evolution, however, has not taken into account the uncertainty that characterizes available information, in particular uncertainty about payoff. In the current experimental microsociety study, participants built weight-bearing devices under social and asocial learning conditions. Information about how well each device performed was never provided to participants, yet participants were more likely to copy higher-performing devices than lower-performing devices when they were able to observe behavior. These results make an important contribution to the study of culture by providing data about response to conditions of uncertainty, as well as the use of strategic social learning predicted by theoretical work.

120 Americana Salon 3 Symposium (cont.): Evolutionary analyses of crime and punishment Organizers: David Buss, Vibeke Ottesen 11:30 Can principles of parental investment predict patterns of child homicide in Norway? Vibeke Ottesen (contact: [email protected]) Evolutionary informed principles of parental investment illuminates the psychology that may underpin the perpetration of child homicide. It also has enabled the prediction of risk factors for child homicide in a range of societies, from traditional hunter-gatherer societies to modern day USA, Canada, Britain, and Italy. The increasing number and range of societies where these principles enable the prediction of risk factors testifies to the universal validity of the inherent understanding of the psychology of child homicide perpetration. An ongoing study of child homicide in Norway, a country with unusually low homicide rates, provides a unique opportunity to test this validity in a previously unexamined culture.

11:50 Darwin on the witness stand: Evolutionary psychology, forensic evaluations, and expert testimony J. Andy Thompson (contact: [email protected]) There is almost no area of the law where psychology, clinical psychology, and psychiatry fail to have impact. Within our justice system every criminal defendant now has a constitutional right to a psychological evaluation. Clinicians determine competency to stand trial and mental state at the time of the offense. Sex offenders undergo evaluations and treatment. In domestic relations courts, partner violence, child abuse, child custody and visitation require clinicians’ assessments, reports and testimony. Parent-offspring conflict invariably surfaces in trust and estate litigation and in challenges to wills. A trial judge must consider whether expert evidence has been tested and subjected to professional scrutiny through peer review and publication. As evolutionary psychology, which is committed to empirical validation, becomes part of mainstream psychology, it will affect our courtrooms. This presentation will outline these changes with case illustrations.

12:10 Moderated discussion David Buss

121 Americana Salon 4 Individual Differences III 11:30 Men’s testosterone responses to competitive threats across their partners’ ovulatory cycle: A test of the challenge hypothesis in men Melissa Fales, Kelly Gildersleeve, Martie Haselton (contact: [email protected]) The challenge hypothesis, supported by studies of nonhuman primates, proposes that male testosterone increases in the presence of fertile females and rises further in the presence of male rivals. We used rigorous methods to examine this phenomenon in men. Thirty-four men were randomly assigned to view highly competitive or average male rivals at high and low fertility (LH confirmed) within their partner’s cycle. Testosterone was measured before and after this manipulation. The fertility by condition interaction fell short of statistical significance. However, the predicted simple effect was significant: controlling for pre-test testosterone levels, men in the high competition condition showed significantly higher post-test testosterone when their partner was at high relative to low fertility, p = .02. This preliminary support for the challenge hypothesis in men builds on a growing literature suggesting that men respond to female fertility cues with increased attraction, hormone levels, and mating-related motivations

11:50 Risk-taking and sexual promiscuity in night owls: Is eveningness an adaptation for short-term mating? Dario Maestripieri (contact: [email protected]) Individual differences in morningness/eveningness are relatively stable over time and, in part, genetically based. The night-owl pattern is more prevalent in males than in females, particularly after puberty and before women reach menopause, suggesting that eveningness may have evolved by sexual selection. Eveningness has been associated with extraversion, novelty-seeking, and in males, with a higher number of sexual partners. In this study, eveningness predicted higher risk-taking. This association was not testosterone-dependent but mediated by cortisol. Female night-owls had cortisol profiles and risk-taking tendencies more similar to those of male night-owls than to those of early-morning females. Female and male night owls were also similar in the proportion of individuals who were single or in short-term romantic relationships. Eveningness appears to be associated with psychological and behavioral traits that are instrumental in short-term mating strategies in both men and women.

12:10 Are risk-persistent individuals adaptive decision-makers? Sandeep Mishra, Martin Lalumiere (contact: [email protected]) Crime and other antisocial risk-taking is generally considered reckless, impulsive, and maladaptive. Risk-sensitivity theory, however, posits that risk-taking is adaptive in situations where decision-makers experience disparity between their present and desired (or goal) state. Risk-taking may therefore represent an adaptive, ecologically rational response to situations of disparity. We examined whether individuals belonging to risk-persistent populations (i.e., drug addicts, gambling addicts, and ex-convicts, among others) make decisions consistent with risk-sensitivity theory in a laboratory setting. We found that risk- persistent populations exhibited risk-taking behavior consistent with the predictions of risk-sensitivity theory. Notably, risk- persistent individuals exhibited “rational” decision-making behavior that did not differ from the behavior of more privileged, risk-averse populations. These results suggest that the high levels of risk-taking observed among people in risk-persistent populations may be a product of “rational”, risk-sensitive decision-making that is sensitive to costs and benefits in everyday social environments.

122 Poinciana 3/4 Applied Evolutionary Psychology 11:30 Is postpartum depression a disease of modern civilization? Jennifer Hahn-Holbrook, Martie Haselton, Christine Dunkel Schetter (contact: [email protected]) Postpartum depression poses an evolutionary puzzle: it is extremely common, yet significantly reduces the fitness of both mothers and offspring. Why has natural selection failed to remove this trait? In this talk, we consider the hypothesis that postpartum depression represents a “disease of modern civilization” – that is, a result of the evolutionarily novel cultural changes in motherhood that have occurred over the last century. Certain diet deficiencies, low breastfeeding rates, and other social, obstetric, and lifestyle changes are associated with inflated rates of postpartum depression in the industrialized world. The evidence for this evolutionary disequilibrium interpretation will be discussed in light of previous hypotheses that postpartum depression is a dedicated adaptation or a byproduct of hormonal changes associated with pregnancy.

11:50 Danger in the eye of the beholder: Discovery of the plateau illusion tests behavioral evolution criticisms Russell Jackson, Chéla Willey (contact: [email protected]) Criticisms of evolutionary hypotheses in human behavior include that the approach is comprised of post-hoc storytelling that reiterates anecdotal common knowledge. However, these criticisms are empirically testable. We tested the predictions made by these criticisms in human vision, a research domain featuring established evolutionary hypotheses and widespread anecdotal experience. Contrary to anecdotal predictions and predictions from dominant vision theories, data from two experiments supported the unique predictions published under Evolved Navigation Theory several years prior to this investigation. This investigation also led to the discovery of a large magnitude, pervasive distance illusion in everyday human vision: The Plateau Illusion. Despite the crucial and widespread nature of these phenomena, they were unknown prior to the current evolutionary investigation. These data suggest that post-hoc anecdotal explanations are not inherent features of evolutionary behavioral hypotheses and that such assumptions deny researchers useful predictive tools. Vigilance against post- hoc storytelling should target all research paradigms.

12:10 Enhancing knowledge about and positive attitudes toward evolutionary theory: Curricular effectiveness as measured by the Evolutionary Attitudes and Literacy Survey (EALS) Patricia H. Hawley, Stephen D. Short (contact: [email protected]) We examined changes in university students’ attitudes toward and knowledge about evolution as measured by the previously validated Evolutionary Attitudes and Literacy Survey (EALS; Hawley et al., 2011) prior to and following completion of either an undergraduate political science, biology (with significant evolutionary content), or evolutionary psychology course. A multiple group repeated measures confirmatory factor analysis was conducted to examine latent mean differences in evolution knowledge/relevance, misconceptions, and creationist reasoning. Significant and notable increases in evolution knowledge/relevance and decreases in creationist reasoning and evolutionary misconceptions were observed for the evolutionary psychology course. For the biology course, there was no significant change in evolution knowledge/relevance and misconceptions increased. Evolution education that pointedly addresses philosophy of science, misconceptions about the theory and its direct relevance for human behavior may demonstrate greater change in students’ knowledge and attitudes. Implications for the national reception of evolutionary theory will be discussed.

123 Saturday, July 20

AFTERNOON SESSION

Americana Salon 1 Cooperation VIII 3:20 Human punishment is motivated by inequity aversion not a desire for reciprocity Nichola Raihani, Katherine McAuliffe (contact: [email protected]) Humans involved in cooperative interactions willingly pay a cost to punish cheats. However, the proximate motives underpinning punitive behaviour are currently debated. Individuals who interact with cheats experience losses, but they also experience lower payoffs than the cheating partner. Thus, the negative emotions that trigger punishment may stem from a desire to reciprocate losses or from inequity aversion. Previous studies have not disentangled these possibilities. Here, we use an experimental approach to ask whether punishment is motivated by inequity aversion or by a desire for reciprocity. We show that humans punish cheats only when cheating produces disadvantageous inequity, while there is no evidence for reciprocity. This finding challenges the notion that punishment is motivated by a simple desire to reciprocally harm cheats and shows that victims compare their own payoffs with those of partners when making punishment decisions.

3:40 Social influences on inequity aversion in children Katherine McAuliffe, Peter Blake, Grace Kim, Richard Wrangham, Felix Warneken (contact: [email protected]) Humans tend to sacrifice personal gain to avoid both disadvantageous inequity (DI) and advantageous inequity (AI). In children these two forms of inequity aversion follow different developmental trajectories, with DI aversion emerging early and AI aversion emerging relatively late. Although inequity aversion is assumed to be a social phenomenon, the role of social context has not been tested in children. Here we report results from a study that compared rejections of unequal reward allocations in children (N = 325) interacting with or without a partner (i.e. social vs. nonsocial). Nonsocial factors (e.g. reference dependence) partly explain rejections of DI when a better alternative is visible. However, social factors play a critical role in eliciting a response to AI. By integrating social and nonsocial factors, this study provides a detailed picture of the expression of inequity aversion in humans and gives us insight into its origins in ontogeny and evolution.

4:00 Cooperative behavior in school children: The influence of vigilance, positive and negative feedback Maria Emilia Yamamoto, Natalia Dutra, Natalia Boccardi, Phietica Silva, Anuska Alencar (contact: [email protected]) The public goods game has been used to investigate cooperation in children and the presence of an adult may influence the amount of donations. We manipulated the influence of the experimenter on children's behavior in a public goods game. 539 children from public schools in Natal, Brazil , aged 5-11 years participated in the games. These children were subjected to eight rounds of a game in which they should decide the amount of anonymous donations to a common fund. At the end of each round, we counted the donations in the presence of the children, multiplied the donations by 3 and shared the total equally among the children. We had 4 conditions: control (7 groups); positive feedback, with praise of large donations (7 groups); negative feedback with criticism of small donations (7 groups); vigilance, when an adult witnessed the donations (6 groups). We found that children cooperated more in the conditions of vigilance and negative feedback. These results are probably related to the expectation of punishment suggested by the feedback or the vigilance.

4:20 Development and transmission of costly punishment in children Gul Deniz Salali, Myriam Juda, Joseph Henrich (contact: [email protected]) Culture-gene coevolutionary theorists have argued that cultural evolution has harnessed different aspects of our evolved psychology to create a variety of different mechanisms for sustaining social norms. One of these mechanisms, opportunities for costly punishment, has emerged in experiments as effective for sustaining cooperation in some societies. If this view is correct, punishment of norm violators should be culturally-transmittable, and applicable to both prosocial and anti-social behaviors. Much existing work shows that prosocial behavior in experiments develops substantially during early and middle childhood. Here, we test children aged 3 to 8 years in a simplified Third Party Punishment Game to investigate whether they imitate a model’s decision on costly punishment both in unfair and fair situations. We find that children, regardless of their age, imitate the costly punishment of both fair and unfair allocations, and the rates of imitation increase with age. However, only older children imitate not-punishing both in fair and unfair conditions. These findings highlight the potential role of social transmission in the stabilization of social norms.

124 4:40 Cognitive adaptations for the delivery of information: The case of spontaneous confession to a victim Daniel Sznycer, Eric Schniter, John Tooby, Leda Cosmides (contact: [email protected]) Concurrent with the evolution of language, hominins faced a vast array of decision points concerning whether, what, when, how, and whom to communicate. This selective regime would have shaped cognitive mechanisms functionally specialized for the delivery of information. Here we focus on the fundamental adaptive problem whether an individual should deliver information to a given other at a given time. The study case is spontaneous confession of an offender to his victim. By hypothesis, offenders do not confess unless the indirect benefits of confession (e.g. enabling a valued victim to remedially change a course of action) outweigh the costs (social devaluation). Moreover, when there is a high probability that the victim will find out about the offense via other routes (e.g. incriminating evidence), confession is expected to net higher benefits and therefore be more compelling. Naturalistic and experimental studies conducted among American and Indian subjects support this model of confession. Adaptationism is a profitable approach to map the regulatory variables involved in this and other communication games as well as the mechanisms governing information accrual.

5:00 Social cognition and food sharing: A study of tolerated scrounging and feeding Thomas Alley (contact: [email protected]) Food sharing is a means of transferring resources that also can convey information about the provider and their relationship to the recipient. Previous research indicates that viewers tend to perceive a pair’s relationship as more intimate if one shares food with the other, particularly if this is via hand-to-mouth feeding. The present study compared tolerated scrounging to feeding. This passive food sharing was expected to produce only a small increase in perceived attraction or intimacy compared to no food sharing. To test this, 256 adults watched five short videos, each showing a different mixed-sex pair of young adults dining together; four of these included a segment in which either feeding or tolerated scrounging occurred. Ratings of perceived involvement and attraction were much higher if a dyad was observed feeding, while tolerated scrounging had only a small effect, showing that how food is transferred is significant, not just what gets shared.

Americana Salon 2 Mating III 3:20 Sexual strategies during pregnancy Jaclyn Ross, Elizabeth Pillsworth (contact: [email protected]) Medical research has established that while the vast majority of women experience a lowered sex drive during pregnancy, a small percentage experience stable or even increased sexual desire. We propose that sexual desire during pregnancy may serve a mate-retention function, and will be affected by perceived threats to the relationship, as well as the partner’s investment and genetic quality. In a survey of 110 pregnant women, we found that perceived threats to the relationship significantly predicted sexual desire (t = 2.278, p = .025). In addition, we found a strong negative relationship between partner’s investment quality and a woman’s sexual desire for partners outside the relationship (t = -3.19, p = .002), and significant interactions of perceived threats to the relationship and partner’s investment quality (t = -3.518, p = .001) and physical attractiveness (t = 3.57, p = .001) in predicting extra-pair sexual desire.

3:40 Changes in mate preferences and selectivity across age cohorts David Frederick, Kelly Gildersleeve (contact: [email protected]) BACKGROUND: Multiple evolutionary perspectives have proposed that men’s mate value increases with age as they accrue resources, and women’s mate value decreases as fertility declines. Personal ads research suggests that older men have higher standards for long-term mates, whereas older women have relatively lower standards. METHOD: We asked nearly 25,000 men and women ages 18- to 65-year-old men to rate desirability of various characteristics (e.g., has children) in a potential long- term partner, ranging from deal-breaker to essential. RESULTS: Contrary to personal ads research, both sexes tended to become somewhat less choosy with age, with the exception that over 50% of women in the oldest age group continued to rate steady income as "essential." CONCLUSION: Results suggest that the demands one makes in the mating market may not always accurately reflect one’s underlying preferences, and patterns of change in preferences across the lifespan may be quite complex.

125 4:00 The relationship between objective risk of sperm competition and men’s copulatory interest in their partner is moderated by the amount of time their partner spends with other men Michael Pham, Todd Shackelford (contact: [email protected]) Men who spend a greater proportion of time apart from their female partner since the couple’s last copulation are at greater objective risk of sperm competition. We propose a novel cue to sperm competition risk: the time she spends with her male friends. Four hundred and twenty men in a committed, sexual relationship completed a questionnaire. The results indicate that men at greater objective risk of sperm competition report less time desired until the couple’s next copulation, greater interest in copulating with their partner, and greater anger, frustration, and upset in response to their partner’s sexual rejection, but only among men whose partner spends more time with her male friends. These results remain after controlling statistically for the participant’s age and their partner’s age.

4:20 Sperm competition risk moderates the link between men’s relationship investment and interest in their partner’s copulatory orgasm Todd Shackelford, William McKibbin, Vincent Bates, Christopher Hafen, Craig LaMunyon (contact: [email protected]) Sperm competition occurs when the sperm of multiple males concurrently occupy a female’s reproductive tract and compete for fertilization. Sperm competition may have been a recurrent adaptive problem over human evolutionary history (Shackelford & Pound, 2006). Women’s orgasm may facilitate selective uptake and retention of a particular man’s sperm (Thornhill & Gangestad, 2008). Men who are more invested in their relationship may experience greater costs in the event of sperm competition and potential cuckoldry. Therefore, these men may be especially interested in ensuring their partner’s copulatory orgasm. We hypothesized that men’s relationship investment would predict interest in their partner’s copulatory orgasm, and that sperm competition risk would moderate the association between relationship investment and interest in partner’s copulatory orgasm. Using structural equation modeling on self-report data secured from 229 men in a committed heterosexual relationship, we tested and found support for these hypotheses.

4:40 Psychological sex differences across cultures: Why biosocial theory explains so little David Schmitt (contact: [email protected]) Evolutionary insights from sexual selection theory, strategic pluralism theory, sexual strategies theory, life history theory, psychosocial acceleration theory, and mismatch theory have helped to explain cultural variations in the degree to which men and women psychologically differ. Biosocial theory, in contrast, has proven problematic in that national levels of sociopolitical gender equality are often positively related (not negatively related) with the size of psychological sex differences. As men and women are treated more equally across cultures, psychological sex differences are larger in terms of Big Five personality traits and the Dark Triad traits of Machiavellianism, Narcissism, and psychopathy; in terms of romantic attachment and love styles; in terms of sociopolitical attitudes and personal values; in terms of clinical depression rates and crying behavior; in terms of tested cognitive and mental abilities; even in terms of physical attributes such as height and blood pressure. Biosocial theory may be frequently cited as it appeals to those who insist humans are psychologically gender-neutral members of the animal world, but it explains very little.

126 Americana Salon 3 Symposium: Cognition, contagion, and consumption: Darwinian decision-making in the marketplace and beyond Organizer: Sarah Hill 3:20 The who, when, and why of human mate choice copying: Attractive women provide a proxy for male quality Christopher Rodeheffer, Sarah Hill, Holly Pettijohn, Megan Osborne, Leah Colburn, Tia Robb (contact: [email protected]) Previous research indicates that women find male targets more desirable when they appear to be desired by other women than in the absence of such cues (i.e., mate choice copying). Because many of the qualities that women desire in mates are not discernible on the basis of appearance alone (e.g., social status, resource access), it is reasoned that this practice might reflect women’s using the presence of other women as a proxy for an unknown man’s mate quality. Here, we explicitly test this hypothesis in a series of three experiments. Our first experiment provides evidence that the presence of an attractive female target increases a man’s attractiveness when she is believed to be the target’s girlfriend, but not cousin or friend. Study two found that the degree to which a female target increases a man’s desirability is positively related to her attractiveness. Study 3 revealed that these effects are suppressed when other indicators of male quality are provided. Results indicate that women may use the presence and attractiveness of other women as a proxy for male quality.

3:40 The effect of ovulation on women's variety seeking: From playing it safe to playing the field Ahsley Rae, Kristina Durante (contact: [email protected]) Previous research finds that the hormones associated with the monthly ovulatory cycle decrease women’s satisfaction with their current partner and increase their desire for new men. But, might ovulation also increase women’s desire for new products? In a series of studies we test how women’s desire for variety in consumption changes depending on when such decisions are made. Findings show that ovulating women have increased preference for variety in consumer product choice. Additional findings reveal that the hormonally regulated effect on variety seeking is mediated by an increase in desire for new men near ovulation. Consequently, minimizing the salience of mate attraction goals suppressed the ovulatory effect on variety seeking. This research identifies a novel biological factor that influences women’s desire for variety and provides some of the first evidence that mating motives can mediate consumer choice.

4:00 Fendi handbags fend off romantic rivals: Women's conspicuous consumption as a signaling system Yajin Wang, Vladas Griskevicius (contact: [email protected]) Conspicuous consumption is believed to function to enhance reproductive fitness. Although past research shows that luxury products can help mating for men, the potential reproductive function of conspicuous consumption for women is unknown. We propose that whereas conspicuous consumption helps men attract mates, it helps women deter romantic rivals. We hypothesize that women might seek and display luxury products to guard romantic relationships, whereby flaunting designer handbags and shoes can function to ward off female rivals. Supporting this idea, a series of experiments found that women’s conspicuous consumption is triggered by threats to romantic relationships. Additional findings reveal that women seek luxury products as signals to other women, whereby brandishing lavish possessions can dissuade other women from poaching the woman’s mate. This research identifies a novel function for women’s conspicuous consumption, while also suggesting that women and men might seek luxury products for different evolutionary reasons.

4:20 The clothes and the man: Authenticity matters in clothing for men T. Andrew Poehlman, Joshua Ackerman (contact: [email protected]) One way for humans to signal mate value is how they dress. However, evolutionary theory suggests men and women could face different pressures in dressing. We hypothesized that—while women have traditionally tried to use dress to boost mate value by enhancing overall appearance—men's dress would be perceived as a cue as to non-physical fitness characteristics (resources, etc.) that could be faked. As such, males seen as dressing authentically should be viewed as valuable long-term mates. Four studies manipulated authenticity of dress styles and clothing brands and found support for our hypothesis. Study 1 found mating-primed men were likely to prefer an authentic brand to trendy brands, however women showed no preference. Study 2 found women perceived men who wore authentic clothing as more attractive, whereas men viewed inauthenticity as more attractive. Study 3 found that high status men were still punished for inauthentic dress, while high status women were not. Finally, study 4 found that priming long-term focus led all participants to reward males who dressed authentically, whereas short-term primes led to increase evaluation of trendy (but not authentic) males.

127 Americana Salon 4 Kinship, Sex, and Orgasm 3:20 Covariates and outcomes of child fostering in two rural Timor-Leste communities Debra Judge, Katherine Sanders (contact: [email protected]) Child fosterage in Ossu -- a traditionally patrilineal mountain community in rural Timor Leste -- is high. Children tend to move toward town, where schools and amenities cluster. Though growth is poor generally, fostered children suffer no growth impairment relative to biological children. We compare fosterage and child growth outcomes in Natarbora, Timor-Leste – a lowland, traditionally matrilineal community with more stem and joint family households. These households are slightly larger, with less fostering than in Ossu. Fostering households are not larger than non-fostering households, but are more likely to include more grandparents. Unlike Ossu, secondary school options for children in Natarbora are limited and older children leave home primarily to attend school. Characteristics of natal families are often reported as motivators for children moving into Natarbora households. Fostered children come equally from patrilineal and matrilineal relatives. Receiving households do not differ from non-fostering households in resource indicators. We compare growth parameters of fostered and biological children in households.

3:40 Family structure, rural livelihoods and child health inequality in Tanzania David Lawson, Monique Borgerhoff Mulder, Margherita Ghiselli, Esther Ngadaya, Bernard Ngowi, Sayoki Mfinanga, Kari Hartwig, Susan James (contact: [email protected]) The role of family structure as a determinant of child health is a perennial research theme in evolutionary anthropology. However few studies consider not only how family structure influences the health of individual children, but also accounts for village and ethnic-level inequalities in child health. Here we model family structure and rural livelihoods as predictors of child heights and weights in an ethnically diverse sample of Tanzanian villages (3500+ households). Polygynous and female-headed households show poorer child health compared to male-headed households, however these associations are not independent of ethnic or village-level differences, suggesting that relationships may not be causal. Households with many older children (5yrs-15yrs) had better child health outcomes, while no. of young children (<5yrs) was not important. Pastoralists had poorer child health than farmers and business workers better outcomes, patterns partially mediated by differences in wealth and food insecurity. Independent of these factors, tribal affiliation accounts for a large proportion of the variance in child health suggesting that a number of unmeasured cultural factors may be important.

4:00 Factors predicting the probability of women initiating sex in relationships Leif Edward Ottesen Kennair, Mehmet Mehmetoglu, Trond Viggo Grøntvedt (contact: [email protected]) Previous studies suggest that men more than women take the initiative to sexual activity in relationships (Hatfield et al., 1988; Kennair et al., 2009; Okami & Shackelford, 2001; Peplau et al., 1977). In the current study women in relationships initiate sex in one third of the last intercourses. Apart from receiving love and intimacy, little is known about possible reasons or predictors for women initiative. In this questionnaire based study we investigate different traits of the two partners and their relationship in order to predict when women take initiative to intercourse. The results of the logistic regression analysis (N=172) indicate that the following four factors were significantly associated with women taking the initiative: Agreeableness of the partner (a subfactor of MVI (Kirsner et al., 2007)), feeling committed to the relationship (Rusbult, 1983), pleasure reasons for engaging in sex (Meston & Buss, 2007) and length of the relationship (<=2 and >2 years). As any of these factors increases, so does the probability that women initiate sex. We estimate probabilities for combinations of different values of these factors.

4:20 Vaginal orgasm as a cryptic female choice system: Selection for penis size and copulatory vigor Geoffrey Miller (contact: [email protected]) Across many species, male genital anatomy and copulatory behavior are shaped by cryptic female choice (sexual selection through female control over probability of fertilization and of re-mating with favored males). In humans, cryptic female choice seems partly mediated by clitoral and vaginal orgasm -- two functionally and neuroanatomically differentiated systems that increase romantic attachment (and hence conception likelihood) with favored men (but not with all men). This talk reviews the recent evidence that vaginal orgasm is especially discriminating about penis size and copulatory endurance, including our recent paper showing that women (N=323) who prefer longer penises are more likely to have vaginal orgasms during copulation, but are not more likely to have vaginal or clitoral orgasms from any other type of stimulation, either with or without a partner. Results suggest a long history of coevolution between vaginal orgasm as a female choice system, and penis size and copulatory endurance as male fitness indicators.

128 Poinciana 3/4 Life History IV 3:20 Inter-generational conflicts over reproductive decisions: A cross-cultural examination of parental presence effects on fitness Cristina Moya, Rebecca Sear (contact: [email protected]) While evidence is growing that grandparents are often beneficial in improving grandchildren’s reproductive outcomes, there may be conflicts of interest between the generations with respect to allocating household resources, including alloparenting. Parents may improve their children’s reproductive success by reducing grandchild mortality, but they may reduce it by delaying their children’s onset of reproduction. While the former has been documented cross-culturally, the latter has only been shown robustly in post-demographic transition settings. Using data from over ten societies – the majority of which are small-scale, pre-industrial, and natural fertility – we test the effects of parental presence on women and men’s reproduction. We find negative parental effects on age-adjusted reproductive success. This seems to be driven by anti-natal parental effects earlier in the target’s life including delaying their adult children’s first births. This is consistent with the older generation winning conflicts over household labor and resources that can be used towards beginning, or maintaining, reproduction.

3:40 The interplay of individual- and community-level postnuptial residence on fertility outcomes: do community norms or individual decisions matter more? Kristin Snopowski, Rebecca Sear (contact: [email protected]) We use data from the Indonesia Family Life Survey (IFLS) to explore how both community norms of postnuptial residence and postnuptial residence itself influence a couple’s fertility. Couples living non-normatively are predicted to suffer fitness costs either because of condemnation from others or an individual-level disadvantage that forces a non-normative choice. We conduct a multi-level poisson model to predict number of live births and living children. Our results show significant group- level variation in the effect of postnuptial residence norms on fertility outcomes. Couples living in normatively virilocal communities have higher fertility regardless of their actual postnuptial residence. Couples living virilocally in uxorilocally or ambilocally normative communities also have higher fertility than those with other postnuptial residence patterns. These results suggest that both individual postnuptial residence and community level postnuptial residence patterns influence individual fertility.

4:00 It’s all in the timing: Opposite effects of childhood and young adulthood psychosocial stress on reproductive timing in Australian women David Coall, James Chisholm (contact: [email protected]) Childhood psychosocial stress has been consistently associated with earlier reproduction in women. Theoretical and empirical studies have focused on early childhood (<8 years) as the sensitive period entraining alternative reproductive strategies. Conversely, energetic theories propose that energy imbalance should delay reproduction. In a sample of 663 pregnant women from Perth, Western Australia, we test the hypothesis that psychosocial stress in early childhood but not in later childhood or young adulthood accelerates reproduction. Women who reported more stressful life events during early (<8 years) or late childhood (9-15 years) consistently showed earlier age at menarche, sexual debut, first pregnancy and first childbirth. On the other hand, in women who experienced higher levels of psychosocial stress in young adulthood, more stress was associated with a delayed age at first pregnancy and childbirth. This suggests that psychosocial stress experienced by women in childhood and young adulthood has opposite effects on reproductive timing.

4:20 What a girl wants: Does childhood adversity fast track desired reproductive timing and increase interest in infants in peripubescent girls? Stephanie Clutterbuck, Daniel Nettle, Jean Adams (contact: [email protected]) Female reproductive timing is accelerated by childhood adversity. We investigated interest in infants as a possible psychological mechanism. Interest in infants is an important adaptation allowing females to gather necessary caretaking skills for successful rearing. Thus girls on faster reproductive trajectories should exhibit an increased interest in infants. We explored the relationship between interest in infants, desired reproductive timing and childhood adversity in a sample of 354 girls aged nine to 14. Participants completed two interest in infants tasks followed by an adversity questionnaire. Interest in infants was not a mechanism of reproductive timing, however it may be an indicator of future reproductive strategy. Girls experiencing greater adversity desired earlier age at first birth but were not more interested in infants. Girls experiencing less adversity were more interested in infants but wanted to delay childbirth.

129 4:40 Early childhood and current life uncertainties predict human female mating strategies Xiaoqin Zhu, Lei Chang (contact: [email protected]) We examined the association between early childhood and current life uncertainties and mating strategies among adult females. Based on online response from 450 Chinese women, early childhood and current life uncertainties, including incidents of disasters and accidents, death of family members, parental absence, family relocation, and daily life stresses such as the lack of parent-child boding and the lack of social support, were associated with short-term mating strategies such as early initiation of first sexual intercourse, short duration of intimate relationship, unrestricted sociosexual attitudes, and reduced desire for both direct and indirect fitness benefits in a potential mate. Some of these life stresses experienced concurrently rather than in early childhood were stronger predictors of short-term mating strategies. These findings support the evolutionary view that women’s short-term mating strategy that is partially calibrated by life history tradeoffs responding to early childhood environmental uncertainties also responds to the immediate environment according to the same evolutionary cost-benefit tradeoff.

5:00 Do life-history strategies and mating orientations translate into desires for children? Gary Brase (contact: [email protected]) Declining fertility rates in resource-rich modern populations are an evolutionary conundrum, but also an opportunity to explore the relevant factors which contribute to the fertility decision making process. Given that immediately available resources are apparently not the only consideration for human reproductive decisions, what other factors are important in current environments? The present studies document that life history strategy and mating orientation measures are significantly related to assessments of infants and children as part of one’s social world. Specifically, “slower” life history strategy and long-term mating orientation were associated with more total desired number of children, more positive assessments of babies, decreased negative assessments of babies, and lower perceived tradeoffs entailed in caring for children. Participants with short-term mating orientations showed an opposite pattern of assessments. These results suggest that short- term mating orientation, and perhaps also “faster” life history strategy, are focused more on low investment sexual activity rather than accelerated reproductive scheduling.

130 Saturday, July 20

NEW INVESTIGATOR COMPETITION FINALISTS

2:00 Meta-analytic review of cycle shifts in women's mate preferences: Findings from complete set of 72 published and unpublished effects Kelly Gildersleeve, Department of Psychology, UCLA, [email protected] Co-authors: Melissa Fales, Martie Haselton To date, over 40 published studies have tested the hypothesis that women’s preferences for sex partners with characteristics that reflected genetic quality ancestrally are elevated on high- relative to low-fertility days of the ovulatory cycle. Some have reported null effects. We conducted a meta-analysis of 72 effects to quantitatively evaluate the magnitude and robustness of cycle shifts in preferences for key characteristics thought to have reflected genetic quality. The primary analysis aggregating across these preferences revealed robust context-dependent cycle shifts; shifts were most pronounced in evaluations of short-term attractiveness and absent in evaluations of long-term attractiveness. Funnel plot and trim-and-fill tests showed no evidence that these cycle shifts were accounted for by publication bias. More focused analyses revealed characteristics for which cycle shifts were or were not robust. Cycle shifts in women’s mate preferences suggest that evolved psychophysiological mechanisms could contribute to day-to-day variation in women’s attractions and social behavior.

2:20 How to learn about teaching: An evolutionary framework and empirical tests from Fiji Michelle Ann Kline, Department of Anthropology, UCLA, [email protected] Co-authors: Robert Boyd, Joseph Henrich Humans are heavily reliant on cultural adaptation, and have coevolved with culture for millennia. Teaching enhances the fidelity of cultural transmission and should be common in such a culture-dependent species. However, existing data present a puzzle concerning the role of teaching in human evolution. While biologists have documented teaching in a number of non-human animal species, extant ethnographic work suggests that teaching is rare in non-Western human societies. Both sets of findings are hotly debated. I argue that disputes about the nature and prevalence of teaching across human societies can be resolved within an evolutionary framework that distinguishes among a range of teaching behaviors with varying costs and benefits to teachers and learners. This framework predicts that some teaching behaviors should be common across societies, within particular relationships, and for the learning of particular kinds of skills. Here I present this new theoretical framework and confirm a number of its predictions using data sets from fieldwork with fishing-horticultural villages on Yasawa Island, Fiji.

2:40 Spatial visualization predicts range size and reproductive success among the Namibian Twe and Tjimba Layne Vashro, Department of Anthropology, University of Utah, [email protected] Co-authors: Elizabeth Cashdan Males occupy a larger range than females in many mammal populations including humans, and show an advantage in certain spatial-cognitive laboratory tasks. Evolutionary psychologists have explained these patterns by arguing that an increase in spatial ability facilitated navigation, which allowed range expansion in pursuit of additional mating and hunting opportunities. This study evaluates this hypothesis in a population with navigational demands similar to those that faced many of our ancestors, the Twe and Tjimba of northwestern Namibia. Twe and Tjimba men have larger visiting ranges than women and are more accurate in both spatial (mental rotations) and navigational (accuracy pointing to distant locations) tasks. Men who perform better on the spatial task not only travel farther than other men, but also have more children with more women. These results support the hypothesis that male mating competition is the selection pressure underlying sex differences in spatial ability, navigation, and range size.

131 Saturday, July 20

POST DOCTORAL COMPETITION FINALISTS

3:10 A mutualistic approach to morality: The evolution of fairness by partner choice Nicolas Baumard, Philosophy, Politics and Economics Program, University of Pennsylvania, [email protected] Co-authors: Jean-Baptiste André, Dan Sperber Human morality is characterized by a specific logic, based on the notion of fairness or proportionality. People think that punishments should be proportionate to crimes, that compensations should be proportionate to torts, that rights should be proportionate to duties or that the distribution of benefits should be proportionate to each individual’s contribution. How can we account for such a logic? Here, I develop an approach to morality as an adaptation to an environment in which individuals were in competition to be chosen and recruited in mutually advantageous cooperative interactions. In this environment, the best strategy is to treat others with fairness and to share the costs and benefits of cooperation equally. In line with this approach, the study of a range of experiments involving property rights, collective actions, mutual help, and punishment shows that participants’ distributions aim at sharing the costs and benefits of interactions in a fair way. Furthermore, this approach may shed new lights on other moral intuitions such as collectivism, parochialism, authoritarianism or puritanism.

3:30 When the economy falters do people spend or save? Responses to resource scarcity depend on childhood environments Vladas Griskevicius, Business School, University of Minnesota, [email protected] Co-authors: Joshua Ackerman, Stephanie Cantú, Andrew Delton, Theresa Robertson, Jeffry Simpson, Melissa Emery Thompson, Josh Tybur When resources are scarce, is the adaptive response to save for the future or to spend on immediate gains? Drawing on life-history theory, we propose that people’s responses to resource scarcity depend on the harshness of their early-life environment, as reflected by childhood socioeconomic status (SES). A series experiments tested how people from different childhood environments responded to resource scarcity. Finding show that people who grew up in lower-SES environments exhibited responses consistent with a fast life history strategy: they were more impulsive, took more risks, and approached temptations more quickly. Conversely, people who grew up in higher- SES environments responded in the opposite manner: they were less impulsive, took fewer risks, and approached temptations more slowly. Responses similarly diverged according to people’s oxidative-stress levels—a urinary biomarker of cumulative stress exposure. Overall, whereas tendencies associated with early-life environments were dormant in benign conditions, they emerged under conditions of economic uncertainty.

3:50 Evolution of cooperation among mammalian carnivores and its relevance to hominin evolution Jennifer E Smith, Department of Biology, Mills College, [email protected] Co-authors: Eli M Swanson, Daphna Reed, Kay E Holekamp Anthropological theory suggests direct links between the origins of cooperation in hominins and a shift toward an energy-rich diet. Although the degree to which early hominins ate meat remains controversial, here we reevaluate the notion, originally suggested by Schaller and Lowther in 1969, that mammalian carnivores can shed light on human origins. Precisely when cooperation evolved in hominins or carnivores is unknown, but species from both groups cooperatively hunt large game, defend resources, guard against predators, and rear young. We present a large-scale comparative analysis of extant carnivore species, quantifying anatomical, ecological, and behavioral correlates of cooperation to determine whether metabolic rate, body and relative brain size, life history traits, and social cohesion coevolved with cooperation. We focus heavily on spotted hyenas, which live in more complex societies than other carnivores. Hyenas regularly join forces with kin and nonkin to hunt large antelope and to defend resources during intergroup conflicts and disputes with lions. Our synthesis highlights reduced sexual dimorphism, increased reproductive investment, high population density, fission-fusion dynamics, endurance hunting of big game in open habitats, and large brains as important correlates of cooperation among carnivores. We discuss the relevance of our findings to understanding the origins of cooperation in hominins.

132 Author Index

3, 69, 70 Aarøe 45 Bicchieri 31 Aaron 11, 19, 26, 44, 92, 114 Bjorklund 56 Abel 55 Black 11, 93 Abrams 12, 58, 94 Blackwell 15, 23, 127, 132 Ackerman 17, 22, 109, 124 Blake 30 Adair 22, 124 Boccardi 129 Adams 20, 118 Boddy 20, 117 Adonna 14, 101 Bolker 7, 80 Aiyer 12, 95 Bone 14, 20, 101, 118 Aktipis 7, 23, 80, 128 Borgerhoff Mulder 13, 97 Alba 15, 131 Boyd 22, 124 Alencar 46 Boyer 50 Alesia 130 Brase 22, 125 Alley 4, 72 Bressler 9, 86 Altman 38 Brothers 9, 88 Alvarado 16, 105 Brown, S 17, 109 Anderson, G 17, 110 Brown, G 61 Anderson, I 61 Brown III 15, 17, 108, 132 André 16, 107 Bryant 5, 12, 14, 36, 74, 96, 101 Andrews 22, 67 Bshary 60 Anton 29 Burriss 39 Aradhye 3, 68 Burton-Chellew 14, 103 Aramburu 6, 19, 21, 35, 40, 77, 116, 121 Buss 28 Arantes 10, 91 Butterfield 3, 69 Arceneaux 7, 82 Buunk 8, 83 Arjona 32, 60 Byrd Craven 19, 50, 115 Arvanitis 40 Byrne 38 Asao 18, 112 C do Lago 11, 93 Atkinson, Q 16, 105 Cabeza de Baca 18, 20, 113, 117 Atkinson, J 12, 96 Caldwell Hooper 60 Auer 60 Calvi 25 Auerbach 5, 75 Camilleri 26 Ayers 19, 114 Cannon 5, 66 Baillargeon 15, 20, 53, 119, 132 Cantu 59 Bajrami, A 35 Cappelle 59 Bajrami, Z 10, 89 Carmona 4, 72 Balshine 62 Carré 8, 44, 84 Barclay 16, 38, 106 Carter 8, 84 Barker 5, 75 Case 4, 16, 41, 71, 106 Barrett 15, 131 Cashdan 22, 126 Bates 33 Castro 15, 17, 108, 132 Baumard 19, 114 Causey 20, 119 Beal 19, 114 Cesario 17, 110 Beall 5, 65 Chagnon 20, 117 Bear 4, 18, 30, 73, 113, 130 Chang 4, 59, 72 Beaussart 6, 78 Chaudhary 8, 84 Benard 13, 98 Chavez 7, 81 Bendixen 12, 94 Chipman 10, 89 Benejam 52 Chishing 28 Berg 129 Chisholm 62 Berzuini 46 Christner

133 8, 85 Clacey 52 Dutch 34 Clint 22, 124 Dutra 9, 88 Cloud 54 Dyble 129 Clutterbuck 29 Earley 13, 99, 129 Coall 14, 101 Earn 7, 82 Cobey 40 Easton 4, 71 Cohen 12, 96 Eaton 23, 127 Colburn 8, 85 Edmunds 19, 114 Cole 19, 49, 115 Ehrke 26 Cole Falek 51, 60 Eisenbruch 35 Conroy 6, 78 Ejstrup 3, 14, 22, 24, 64, Cosmides 3, 68 El Mouden 68, 69, 100, 125 61 Elzatma 43 Costa 37 Ermer 60 Cowan 9, 87 Ettinger 17, 110 Crandall 13, 97 Falcon 17, 110 Cross 15, 21, 122, 131 Fales 53 Crysel 9, 87 Faurie 61 Cunningham 5, 28, 33, 74 Feinberg 25 Curry 16, 105 Fernandes 57 Dachslager 50 Fernandez, A 42 Dahlgrun 61 Fernandez, N 42 Dale 10, 14, 25, 34, 90, 102 Fessler 11, 19, 92, 116 Daly 18, 111 Fiddick 5, 75 Dane 9, 52, 88 Fieder 47 Danielsbacka 8, 16, 85, 105 Figueredo 4, 44, 73 David-Barrett 36 Filip-Crawford 33 De Araújo 9, 15, 16, 34, 88, 104, 107 Fincher 9, 88 De Jesus 5, 16, 18, 27, 28, Fink 47 De Smet 25, 74, 107, 112 20, 117 Deaner 7, 15, 16, 34, 82, 104, 107 Fisher 17, 108 Debove 4, 71 Flamson 5, 7, 9, 15, 16, 34, DeBruine 6, 77 Fleischman 74, 82, 87, 88, 104, 107 14, 101 Flinn 10, 36, 91 Del Giudice 13, 46, 97 Forster 28 Deloux 12, 62, 96 Fox 10, 20, 49, 91, 119 DelPriore 5, 28, 33, 74 Fraccaro 3, 14, 15, 68, 69, 100, 132 Delton 41 Frankenhuis 4, 73 Derex 22, 125 Frederick 9, 86 DeScioli 59 Freire 62 Diamon 30 Fukukawa 13, 98 Diaz 11, 93 Funcke 11, 93 Diggle 8, 85 Funder 32 Dillon, H 16, 106 Gaissmaier 51 Dillon, L 40 Gambacorta 17, 109 Dragojevic 12, 18, 96, 112 Gangestad 8, 66 Duchaine 58 Garcia, A 20, 118 Duda 13, 99 Garcia, J 50 Dufey 16, 105 Garcia, R 43 Duguid 17, 109 Gasiorek 4, 25, 44, 54, 58, 73 Dunbar 39, 48 Geher 16, 55, 105 Dunkel 4, 71 German 21, 123 Dunkel Schetter 14, 102 Gervais 6, 20, 23, 76, 119, 127 Durante 33, 53 Gesselman

134 30 Ghai 15, 132 Holekamp 23, 128 Ghiselli 50 Holland 62 Gibbons 10, 89 Holman 15, 21, 22, 122, 125, 131 Gildersleeve 32, 38 Hone 37 Giosan 12, 94 Hooper 39, 48 Gleason 34 Hõrak 4, 73 Godelle 55 Horita 40 Goetz, C 9, 88 Huber 26, 48 Goetz, A 38, 41 Hudson 62 Goetz, S 48 Hummel 6, 76 GoñI 32 Hurwitz 46 Goodman-Wilson 16, 105 Hutz 10, 89 Goodreau 56 Ihara 51 Goranson 10, 89 Inaba 34 Gordon, C 41 Inoue 8, 83 Gordon, D 17, 108 Ishihara 36 Gott 55 Ito 9, 87 Graham 11, 93 Ivens 19, 67 Gray 20, 21, 42, 117, 123 Jackson 18, 112 Grebe 12, 95 Jacquet 37 Greene 12, 20, 94, 118 Jaeggi 51, 60 Grillot 23, 128 James 6, 10, 15, 20, 23, Griskvicius 60 Janssen 53, 76, 91, 119, 127, 132 9, 88 Jasien 23, 128 Grøntvedt 6, 78 Jensen 20, 118 Grossman 11, 92 Ji 11, 93 Gurney 25 Johnson 12, 20, 22, 94, 118 Gurven 53 Jokela 27 Habenicht 50, 53 Jonason 53 Hadden 31 Jones, N 22, 126 Hafen 27, 37 Jones, A 10, 12, 89, 96 Hagen 5, 7, 9, 15, 16, 29, 33, 34, 74, Jones, B 7, 15, 16, 82, 104, 107 Hahn 82, 87, 88, 104, 107 10, 21, 90, 123 Hahn-Holbrook 60, 61 Jordan 4, 71 Hamlin 22, 124 Juda 58 Hammond 23, 128 Judge 55 Hanari 45 Junikka 29 Hart 9, 16, 88, 107 Kandrik 23, 128 Hartwig 12, 94 Kaplan 17, 41, 108 Hasegawa 4, 59, 72 Kaufman, J 6, 15, 16, 21, 77, Haselton 4, 72 Kaufman, S 107, 122, 123, 131 30 Kawahito 33 Hattori 55 Kawano 21, 123 Hawley 18, 27, 112 Keller 11, 92 He 52 Keltner 11, 92 Hehman 23, 128 Kennair 32 Heintz 61 Kennison 15, 21, 22, 120, 124, 131 Henrich 3, 6, 65, 76 Kenrick 10, 89 Hess 40 Ketelaar 16, 107 Hiew 57 Kevern 10, 20, 23, 49, 91, 119, 127 Hill 37 Kiehl 50 Hoffmann 10, 89 Kim, J-H 6, 78 Høgh-Olesen 14, 100 Kim, S 10, 14, 25, 90, 102 Holbrook 22, 124 Kim, G

135 28 King 42 Lutz 26 Kirkpatrick 57 Lycett 61 Kisley 4, 72 Lynch 31 Kito 48 Lynn 41 Kiyonari 53 Määttänen 42 Klebba 11, 45, 92 Mace 28 Klimaj 54 MacEacheron 36 Klimczuk 26, 44, 47 Machluf 9, 88 Klimek 8, 83 Madden 15, 131 Kline 32 Madison 7, 82 Klipping 21, 36, 122 Maestripieri 3, 69 Klofstad 43 Makhanova 62 Knapp 5, 75 Maner 28 Knutson 61 Mani 57 Kogure 8, 84 Mappes 31 Komiya 39 Marczyk 12, 66 Konner 5, 75 Marini 34 Kosiak 9, 86 Marlowe 27, 37 Kramer 31 Marsh 3, 68, 69 Krasnow 18, 27, 112 Martin 25 Krems 28 Matts 7, 16, 80, 105 Kruger 43 Maxwell 9, 87 Krupp 28, 51 McAndrew 46 Kuhle 22, 124 McAuliffe 10, 91 Kuo 11, 92 McBurney 7, 14, 81, 100 Kurzban 16, 106 McCanney 17, 110 Laland 51 McCoy 21, 122 Lalumiere 56 McCrohon 4, 73 Lamba 13, 14, 16, 36, 38, McCullough 22, 126 LaMunyon 46, 97, 100, 106 16, 18, 106, 113 Langen 19, 114 McDonald 52 Larrabure 17, 110 McGlasson 6, 77 Larson 13, 97 McIlwain 3, 69 Laustsen 22, 25, 26, 126 McKibbin 28 Lawrence 20, 117 Mead 23, 128 Lawson 23, 128 Mehmetoglu 35 Lawton 19, 115 Meskill 8, 83 Lea 4, 57, 73 Mesoudi 4, 70 Lee, V 61 Messer 18, 27, 112 Lee, A 40 Meston 16, 107 Lefevre 23, 128 Mfinanga 21, 120 Legare 44 Micklos 43 Leitão 31 Mifune 5, 75 Leknes 20, 117 Migliaccio 15, 104 Lenfesty 6, 78 Migliano 61 Leonard 83 Miguel 48 Li 37, 43 Miller, S 9, 13, 32, 87, 97 Lieberman 23, 128 Miller, G 16, 34, 107 Little 16, 18, 106, 113 Minich 27 Lloyd 21, 44, 122 Mishra 3, 70 Lopez 18, 111 Mitchell 17, 110 Lorince 18, 27, 112 Mitchem 9, 87 Lummaa 10, 53, 91 Mittal 37 Lund 31 Mize

136 37 Mogoase 30 Peng 45 Molleman 61 Penner 29 Moncur 8, 83 Penton Voak 62 Monk 8, 84 Pepper 61 Morgan, L 6, 7, 77, 81 Perilloux 17, 110 Morgan, T 7, 16, 82, 107 Perrett 12, 29, 94 Morrison 11, 92 Perry 43 Motlagh 61 Peszka 23, 129 Moya 3, 6, 69, 70, 78 Petersen 9, 88 Muller 41 Peterson 8, 83 Mulvaney 23, 127 Pettijohn 8, 50, 83 Muñoz Reyes 22, 26, 126 Pham 37 Muresan 39, 48 Philip 4, 73 Murray 14, 102 Piazza 21, 120 Muthukrishna 4, 10, 71, 90 Pietraszewski 47 Myers 34 Piirisalu 36 Nagoshi 16, 22, 107, 125 Pillsworth 20, 117 Naidoo 31 Pineda 56 Navarrete 14, 19, 24, 64, 102, 116 Pinker 18, 112 Neave 7, 82 Pipitone 9, 36, 76 Neel 17, 34, 35, 36, 109 Pirlott 7, 79 Németh 5, 28, 33, 74 Pisanski 9, 88 Nenko 19, 115 Pisor 8, 84, 129 Nettle 8, 54 Pita 6, 17, 76, 109 Neuberg 58 Plowright 28 Neuser 23, 127 Poehlman 39, 48 Newmark 10, 90 Pollack 46 Newton 7, 82 Pollet 23, 128 Ngadaya 11, 93 Popat 23, 128 Ngowi 9, 86 Pound 9, 87 Nitsch 9, 86 Price 17, 108 Nowak 49 Prokosch 45 O’Brien 29 Puts 5, 28, 33, 74 O’Connor 8, 45, 84 Puurtinen 61 O’Gorman 46, 47 Radtke 49 Oaten 20, 23, 119, 127 Rae 30 Oda 12, 22, 95, 124 Raihani 31, 40 Ohtsubo 17, 108 Rand 17, 108 Ohtsuki 7, 80 Rauch 41 Okanoya 4, 73 Raymond 8, 85 Olderback 6, 76 Redden 52 Olsacher 15, 132 Reed 40 Orr 62 Rees 41 Osawa 8, 84 Reeve 23, 127 Osborne 5, 17, 74, 109 Reid 19, 21, 116, 121 Ottesen 58 Reissing 16, 106 Panis 7, 79 Reynolds, T 11, 92 Pashos 27 Reynolds, N 55 Patch 18, 112 Ried 32 Paulin 23, 127 Robb 13, 14, 16, 38, Pedersen 58 Roberts, Sam 46, 97, 100, 106 7, 9, 16, 82, 87, 107 Roberts, S Craig 17, 109 Peinado 14, 15, 100, 132 Robertson 26 Penaloza 17, 109 Robinson

137 43 Rocha 7, 82 Shoup Knox 10, 23, 49, 91, 127 Rodeheffer 21, 120 Shulman 5, 16, 27, 28, 74, 107 Röder 18, 111 Sidanius 26 Romero 22, 124 Silva 6, 51, 60, 77 Roney 6, 77 Simmons 12, 95 Rosas 54 Simons 38, 41 Rosetti 62 Simpson, A 16, 105 Ross, K 10, 15, 20, 53, 91, 119, 132 Simpson, J 22, 125 Ross, J 29 Singh 17, 109 Rottman 19, 114 Sjoberg 12, 96 Roulette 18, 113 Skufca 60 Rubin 56 Smaldino 37 Rusu 15, 132 Smith, J 59 Rutherford, J 53 Smith, C 4, 70 Rutherford, M D 13, 97 Smith, A 44 Sääksvuori 129 Snopowski 22, 124 Salali 13, 98 Solano 11, 92 Salmon 44 Sparks 8, 83 Sanchez Pages 15, 132 Sperber 23, 128 Sanders 7, 82 Sprengelmeyer 6, 76 Sang 52 Stafford 52 Saphire Bernstein 61 Stansbury 52 Saslow 50, 62 Starratt 52 Saturn 48 Steele 7, 80 Schacht 16, 39, 107 Stephen 28 Schaefer 12, 94 Stieglitz 13, 99 Schaffnit 7, 80 Stone, E 17, 110 Schaller 35 Stone, H 16, 106 Scheibehenne 13, 99 Strassmann 29, 62 Scheyd 12, 96 Sullivan 57 Schillinger 10, 91 Sung 43 Schirmer 49 Sutton 22, 126 Schmitt 8, 85 Swanepoel 22, 125 Schniter 15, 132 Swanson 8, 84 Schroeder 37 Szentagotai 11, 92 Schwartz 22, 125 Sznycer 9, 86 Scott, I 7, 79 Takács 37 Scott, N 41 Takahashi, H 11, 93 Scott Phillips 10, 89 Takahashi, N 13, 23, 99, 129 Sear 55 Takezawa 9, 87 Segal 56 Tamura 19, 49, 115 Sela 31 Tanaka 10, 90 Sell 62 Tang 19, 47, 114 Sellers II 41 Tanida 19, 22, 48, Shackelford 47 Tanskanen 49, 51, 115, 126 11, 92 Tao 51 Shattuck 17, 108 Tarnita 10, 90 Shaw 62 Tartar 18, 111 Sheehy Skeffington 39, 48 Tauber 13, 99 Sheppard 9, 87 Taylor 8, 85 Sherman, R 8, 85 Thomas, Kevin 16, 18, 106, 113 Sherman, A 14, 102 Thomas, Kyle 20, 118 Sherwood 62 Thomason 21, 123 Short 21, 121 Thompson, J A

138 46 Thompson, R 29, 51 Welling 9, 15, 88, 132 Thompson, M 14, 103 Wendorff 5, 75 Thomsen 16, 105 Wenner 15, 104 Thornhill 58 Wentland 45 Thulin 4, 70 Wertz 5, 28, 33, 74 Tigue 3, 68 West 6, 16, 17, 76, 106, 110 Todd 6, 76 White 43 Tomasello 16, 107 Whitehead 3, 14, 22, 24, 64, Tooby 39, 48 Widman 68, 69, 100, 125 4, 72 Wilbur 7, 81 Townsend 3, 68 Wild 36 Traficonte 20, 118 Wildman 8, 54, 83 Turiegano 16, 18, 106, 113 Wilke 15, 104, 132 Tybur 16, 106 Wilkes 42 Uller 63 Wilkin 41 Ulloa 20, 21, 117, 123 Willey 30 Usami 7, 79 Winegard 48 Valentine 17, 108 Winking 54 van de Wiel 8, 85 Wolf 45 van den Berg 16, 106 Wood 45 van Leeuwen 16, 105 Woodley 47 Vanspeybroeck 22, 124 Wrangham 38 Vargas 18, 27, 112 Wright 15, 131 Vashro 11, 92 Wu, Jia-Jia 21, 120 Vasilescu 18, 113 Wu, Jing 47 Verplaetse 26 Wyckoff 58 Vlahovic 6, 43, 78 Wyman 5, 18, 75, 113 Volk 4, 70 Wynn 62 Vollrath 52 Xiaoping 38, 39 Vonk 11, 92 Xu 30 Wadian 31, 40 Yagi 3, 69 Waismel Manor 31 Yamada 54 Waldorp 13, 14, 98, 103 Yamamoto, J 12, 94 Wallner 22, 43, 124 Yamamoto, M 23, 127 Wang 32 Yokota 27, 37, 63 Ward 53 Young, E 22, 124 Warneken 36 Young, T 21, 120 Wasielewski 31 Yuki 10, 90 Watson 5, 17, 74, 109 Zhang 28 Wearden 130 Zhu 33, 53 Webster 18, 27, 112 Zietsch 18, 35, 112 Weege 10, 90 Zilioli 19, 48, 49, 51, 115 Weekes-Shackelford 7, 80 Zimmerman 39 Wei Tan 20, 118 Zrzavý 20, 119 Weisberg 51 Weisfeld 45 Weissing

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HBES 2013 Competition Committees

New Investigator Post-Doctoral Poster Committee Committee Committee David Buss Martie Haselton Josh Tybur Daniel Fessler Martin Daly Daniel Nettle Bobbi Low Russell Jackson Dave Feinberg

Program Sub-Committee Nicole Hess Ed Hagen Andreas Wilke Eric Pedersen

HBES Executive Council President Elect: Mark Flinn President: Randy Thornhill Past-President: Pete Richerson Treasurer: Ray Hames Secretary/Archivist: Robert Kurzban Publications Committee Chair: Steve Gaulin Student Representative: Christina Larson Council Member at Large: Larry Sugiyama (2013), Sara Hrdy (2013), Todd Shackelford (2015), Catherine Salmon (2015), Clark Barrett (2017), Lisa DeBruine (2017)

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