Founders of Evolutionary Psychology

Home , David Buss, John Tooby, Leda Cosmides, Margo Wilson, Martin Daly (professor), The Adapted Mind

Founders of Evolutionary through natural, social, or sexual selection. They Psychology are context-dependent and process information according to specific rules as selected for. This Leif Edward Ottesen Kennair may by many be called the Santa Barbara school Department of Psychology, Norwegian of evolutionary psychology, but that specific University of Science and Technology, approach has been somewhat broadened by a Trondheim, Norway greater interest in sex differences and individual differences during the last decades. Founders are those who contributed to the formation of the Synonyms psychological evolutionary research program as it may be recognized today, especially as opposed David Buss; John Tooby; Leda Cosmides; Margo to other evolutionary research programs within Wilson; Martin Daly human behavioral science such as human behavioral ecology or gene-culture coevolution. Foun- ders presented in the following include John Definition Tooby and Leda Cosmides, Margo Wilson and Martin Daly, and David Buss. These were histor- Evolutionary psychology is a psychological sci- ically the five scholars who worked on the very ence where hypotheses are informed by evolu- first “Foundations of Evolutionary Psychology” at tionary theory (especially middle-level theories, Palo Alto. such as Trivers’ parental investment theory or life history theory, see Buss 1995), as well as a consideration of known features of the species’ rele- Introduction vant evolutionary past, i.e., relevant selection forces. In addition, there is a specific model of Evolutionary psychology was founded in the mind, where one considers the mind made up of a 1980s, developed into a comprehensive and mosaic of mental mechanisms. This form of mod- burgeoning field during the 1990s, and slowly ularity follows Pinker’s(1997)definition where became an integrated part of psychology in gen- modules are only partially informationally com- eral the last 20 years. Considering the foundations partmentalized, not Jerry Fodor’s more informa- of evolutionary psychology therefore warrants a tionally encapsulated definition, as the modules look at papers written during the 1980s and the are partly interacting and partly informationally early 1990s, as well as work that has influenced encapsulated. These mechanisms are designed the field the last 30 years.

# Springer International Publishing AG 2016 T.K. Shackelford, V.A. Weekes-Shackelford (eds.), Encyclopedia of Evolutionary Psychological Science, DOI 10.1007/978-3-319-16999-6_1855-1 2 Founders of Evolutionary Psychology

There are three major research labs/groups that this was in the development of any scientific psy- may be recognized as foundational and will be chology. Certainly Darwin’s work on human emo- considered in greater detail in this chapter, tions is one of the first works on human although they all met at Harvard: John Tooby psychological features from an evolutionary per- and Leda Cosmides, founding directors of the spective, and he is also one of the first develop- Center of Evolutionary Psychology at the Univer- mental psychologists with his observational study sity of California at Santa Barbara; Margo Wilson of his own child published in Mind. Pioneers such and Martin Daly, McMaster University, Canada; as William James and Sigmund Freud also were and David Buss, at Harvard, University of Mich- famously interested in phylogenetic musings and igan, and the University of Texas at Austin in speculation. Prominent mainstream theorists such charge of the evolutionary psychology and indi- as John Bowlby and Mary Ainsworth were explic- vidual differences graduate program. itly evolutionary, despite many current attachment The current chapter will provide a brief intro- scientists downplaying the evolutionary founda- duction to some of the most influential contributions of their classical theoretical work. Within tors to the formulation and foundation of anxiety theory, mainstream clinical work has mainstream evolutionary psychology (EP). This always been based on an appreciation of the research program was developed through more or evolved functional underpinnings (Kennair less formal meetings over several years, but was 2007; Marks and Nesse 1994). However, none most clearly formulated by John Tooby and Leda of these previous evolutionary approaches to Cosmides as what is sometimes referred to as the behavior or psychology were part of an organized Santa Barbara school. Parallel to Tooby and theoretical framework or research program. The Cosmides’ empirical work, Margo Wilson and most influential approach to human evolved Martin Daly published large studies based on behavior prior to the advent of evolutionary psy- basic EP principles. The major communicator of chology was human sociobiology, strongly EP within academia is probably David Buss, who influenced by E.O. Wilson’s popular work on in addition to large empirical studies also added a sociobiology, heralding the use of recent theoret- focus on sex differences to the mainstream EP ical developments in evolutionary biology to research program, as well as personality and indi- investigate behavior in animals, including vidual differences. While many more humans. researchers – both independent and collaborators It is important to note at this point the differ- of the aforementioned – have also contributed to ence in considering manifest behavior versus con- mainstream modern EP, this chapter will be sidering the underlying evolved mental restricted to the basic contributions of these five mechanisms. Dennett suggested that EP is merely founders. the marriage of sociobiology with cognitive science. This might not fully appreciate the complex- Evolutionary Psychology Is Not Sociobiology ity of focusing on the adaptation as a cognitive Historically, evolutionary psychology is obvi- structure (Kennair 2002). Once one accepts men- ously not the first evolutionary approach to behav- tal mechanisms as the relevant object of study, ior, psychology, or human nature. In Origin something behaviorists such as Wilson was hesi- Darwin is often quoted as pointing out that he tant to do, this affects both methods and how one believes that “In the distant future I see open fields implements theory in generating hypotheses. for far more important researches. Psychology First, one stops primarily counting babies; that will be based on a new foundation, that of the is, one stops to primarily consider current selec- necessary acquirement of each mental power and tion or adaptiveness. Don Symons was dismissive capacity by gradation.” of evolutionary oriented scholars who sought a This is an interesting quote, but from a histor- psychologically agnostic science, where humans ical perspective, it is important to note how early are fitness maximizers. Cosmides and Tooby Founders of Evolutionary Psychology 3

(1987) provide the link between manifest behav- Trivers (1972, 1974) might be implemented in ior and evolutionary science: the evolved psycho- research. George Williams also provided funda- logical adaptation. mental insight, through the focus on formal It takes time to construct human mental mech- criteria of the adaptation. It is important to note anisms through selection. Human universals, and that the field also in general clearly identifies with thereby the cognitive underpinnings of our human Williams’ refutation of group selection and his nature, have to have been in place before humans focus on the adaptation. From an evolutionary migrated out of Africa. It is therefore not neces- psychology perspective, group selectionist sarily our current environment we are adapted to, models are moot. Thus evolutionary psycholo- but rather the relevant selection forces that were gists in general take a Darwinian, gene level selec- stable enough across deep time to design the men- tionist approach, focusing on inclusive fitness and tal mechanisms that make up universal human middle-level theories (i.e., Trivers 1972) or spe- nature. Environments change faster than selection cific versions of these (i.e., sexual strategy theory, can form adaptations, especially when species Buss and Schmitt 1993) that may generate testable migrate as far as humans have. Such mismatch hypotheses and predictions (Buss 1995; Ketelaar makes it less relevant to consider current adap- and Ellis 2000). tiveness, but predictable output from hypothe- In addition to focusing on identifying mental sized mental adaptations may be studied, and adaptations and using middle-level theories, an design features may be discerned based on such evolutionary psychology approach builds on output. what is known about the species’ relevant evolu- While sociobiology considered current adap- tionary past: the relevant selection forces or the tiveness and built upon a behaviorist psychologi- environment of evolutionary adaptedness (EEA). cal model that studied behavior in current Knowledge about selection forces may suggest environments, evolutionary psychology predicts how specific traits could be shaped today. The that mental mechanisms have been formed over combination of these two aspects provides the evolutionary time due to middle-level evolution- evolutionary basis of evolutionary psychology ary theory and available knowledge about the hypothesis and prediction generation. relevant selection forces (EEA). Evolutionary At this point it may also be important to note psychology thus focuses on adaptations and is the following: Evolutionary psychology is not a inherently founded on a mainstream social- comparative approach, like sociobiology often cognitive psychology model of mind. This shift was. Other species have had species-specific made evolutionary psychology more relevant for selection that has formed the adaptations that mainstream psychological science. In summary, define those species; the same is true for human where sociobiology was founded on the psycho- evolution. Considering what model species to logical theory of behaviorism, which studied choose when attempting to consider either warfare observed behavior and considered whether this or sexual behavior is hard enough; chimpanzees was currently adaptive, evolutionary psychology and bonobos are both related to humans to an was founded on mainstream cognitive theory, equal degree, but differ dramatically in those two which studies the results of mental processing specific areas. Furthermore, many of the most and considers the underlying evolved mental interesting human psychological phenomena are adaptations. species-specific and demand a consideration of specifically hominin evolution. That said, it is Basic Evolutionary Underpinnings the same underlying middle-level theories that Dawkins has had a great influence on EP through describe the selection mechanisms in all species. his synthesis of how selectionist reasoning and the new (in the 1970s) theories of behavioral and social evolution by Hamilton (1964a, b) and 4 Founders of Evolutionary Psychology

A Short Introduction to Evolutionary generate original, testable hypotheses and predic- Psychology tions (Buss 1995; Tooby and Cosmides 1990b). Evolutionary psychology is really indistinguish- These predictions are often concerned with spec- able from mainstream psychology if one considers ifying the functionally specified mental mecha- research methods, statistics, or even to a large nisms, and specific predictions will suggest how degree the journals evolutionary psychologists these will process relevant information. This func- publish in. And despite what some critics argued, tional cognitive approach to hypothesis genera- there probably are no differences in politics either tion is at the heart of what makes evolutionary (Tybur et al. 2007). More than traditional social psychology stand out among psychological psychologists, and despite changes in the last research programs. While most psychologists decade, evolutionary psychologists share a natural probably agree with evolutionary theory being science epistemology and an acceptance of biolog- the only explanation of how life has diversified ical underpinnings to social cognition. That is not and adapted to local ecological demands, psychol- surprising given the fact that the most basic tenet of ogists in general seldom consider how evolution- evolutionary psychology is that many relevant ary middle-level theories can help specify the human psychological abilities, traits, or phenom- information-processing mechanisms they study. ena are the results of directional natural, social, or Also, evolutionary theory is generally considered sexual selection. explanatory, not hypotheses generating. Further, One of Cosmides and Tooby’s foundational while in the recent years most psychologists, even contributions is the formulation of how the mind within social psychology, will accept a biological is best conceived within evolutionary psychology. underpinning of mental activity, continued resis- While many other psychological theories either tance to considering human behavior as a result of have no precise formulation of how the mind natural and sexual selection still exists. may be understood, evolutionary psychologists suggest that the mind is best understood as a A Meeting During an Earthquake mosaic of mental mechanisms. This is what is Ground shifting science rarely happens while the referred to as the modular mind. These modules ground actually shakes. It did for evolutionary are not fully informationally encapsulated; they psychology. In the years 1989–1990 (during are partially interconnected and communicate which the Loma Prieta earthquake occurred), with each other, but particular parts are not David Buss collected five major names within connected to all other parts, and they all process evolutionary psychology at the Center for information differently. These modules are, as Advanced Study in the Behavioral Sciences in stated above, considered to be mental adaptations, Palo Alto for a special center project entitled results of selection. They are therefore behavior- “Foundations of Evolutionary Psychology.” generating mental organs evolved to solve spe- Although no great manifest was published, there cific tasks relevant to reproduction and survival. is little doubt that this was an important meeting They are therefore also context dependent to some given the theoretical and empirical output over the degree, with a certain expectation of specific next few years from all involved. The five were, of forms of input. These mechanisms contributed to course, Margo Wilson, Leda Cosmides, John increasing fitness due to processing information Tooby, Martin Daly, and David Buss. These are according to certain rules and generating fitness- therefore the founders whose work and contribu- enhancing behavior in evolutionary relevant ecol- tions will be considered in further detail below. ogies in our species’ past. The sum of these mental adaptations and their output make up human uni- Wilson and Daly: Young Male Syndrome versal nature. and Homicide Methodologically, as mentioned above, the Margo Wilson and Martin Daly are two of the aim is to apply knowledge about the past environ- most important pioneers of empirical research ment and evolutionary middle-level theories to into human behavior from a psychological and Founders of Evolutionary Psychology 5 evolutionary perspective. Science only grows and foundations of human warfare. The paper also matures through data collection and hypothesis considers general risky behavior among young testing. While theoretical contributions are neces- men, including gambling. sary to formulate a research program and develop Risky lifestyle choices, including risk-taking the hypotheses to be tested, without empirical behavior, lead to increased mortality. Kruger and research, there will be little development. Nesse’s studies on male to female mortality ratios Beyond their own scientific contributions, it is have continued this line of work. Being born male probably a safe claim that they influenced the field is the greatest epidemiological risk factor for early immensely with their editorship of the Human mortality in Western countries. Research on risk Behavior and Evolution Society flagship journal. versus worry highlights how both women in gen- This journal changed its name from Ethology and eral might worry more, but men – especially Sociobiology to Evolution and Human Behavior, young men – may be in danger due to being marking both theoretical development and its hypophobic, a concept used by Marks and Nesse increased scientific impact. to describe less than normal levels of anxious activation. The concept of the young male syn- Young Male Syndrome drome therefore sets the stage for a different Sex differences are still a source of controversy appreciation of relevant health psychology and within the social sciences and even to some degree safety and risk phenomena based on an under- within psychology. Many differences are quite standing of the function of reduced anxiety and small, and generally evolutionary psychology is greater risk-taking behavior in a specific subset of not as interested in such differences: Relevant the population. differences must have been due to stable evolutionary selection forces over evolutionary time Homicide and differences predicted by evolutionary Who kills who? And when and why do people kill middle-level theories. each other? Daly and Wilson’s(1988) classical Who will take the most risk? Based on sexual book Homicide was groundbreaking as it was selection theory and analyses of age and sex, explicitly based on an evolutionary approach to Wilson and Daly (1985) point out that those who behavior. Most importantly, and despite a back- have had the greatest reproductive competition ground in comparative psychology, it focused on and are at greatest danger of not reproducing are specific human behavior, and it left mere theoret- young men. They consider how many violent ical speculation behind: It backed up several of the crimes may be the result of status competition, theoretical a priori predictions with evidence from however petty the situations that can lead to vio- official registers. This was novel. As such, it lence among men might seem (e.g., bar fights). mapped an epidemiology of violence and abuse These male-male violence and status competitions from an evolutionary psychology perspective, are driven ultimately by increased reproductive actually stating this explicitly and using the con- success among young men who can acquire sta- cept of evolutionary psychology in the foreword. tus, as risk-taking behavior including crime and From violent crimes to killing of kinfolk, Daly violence has historically been one possible avenue and Wilson chronicled different aspects of the to greater status for disenfranchised young men. history of homicide, human life history, evolved They report how specifically young males but not sex differences, and the killing of family young females show a surge of violent crime after members. puberty. Without the young male syndrome, many One of the most discussed and challenged crimes might not be committed. War might not results of this evolutionary approach to murder even be possible without this effect. One needs a and abuse was the Cinderella effect, the increased certain hypophobia concerning one’s own mortal- likelihood of stepparents killing their partner’s ity, as pointed out by Tooby and Cosmides in their child, compared with biological parents killing analysis of the necessary psychological their own children. This finding has been 6 Founders of Evolutionary Psychology challenged both on the basis of findings from science, but highlighted the necessity of func- different countries and on the basis of bias in the tional analysis, which they rightly claimed given registration of murder and abuse of children. In their own fruitful methodology is not an explana- both cases, correcting the sample statistics sug- tory luxury; it is a tool which when properly gests that there might be differential rates of mur- applied provides novel insights into how cogni- der across nations as well as a bias for registration tive mechanisms function. of stepparents as perpetrators, but in general the Cinderella effect is supported and robust, and no Culture, Learning, and Evolved Human other explanation has outcompeted the original Universals evolutionary perspective. As a side note, even if In one of the most provocative and misunderstood one resorts to attachment theory for a competing essays, Tooby and Cosmides (1992) identify and explanation, it is surprising that critics are not criticize the Standard Social Science Model aware that in their eagerness to refute one evolu- (SSST). They suggest that explanations of behav- tionary perspective, they are actually invoking ior that rely merely on invoking the general con- another. Finally, it is important to make clear cepts of culture or learning as explanations in how the Cinderella effect works: Many believe themselves – without actually explaining the that Daly and Wilson are suggesting that humans, mechanism of transference in detail – are not like lions taking over another male’s pride, kill scientific. This criticism caused reactions, includ- children that are not theirs to increase their own ing a misplaced conclusion that evolutionary psy- fitness. This is explicitly not what Daly and Wil- chology is adverse to learning in general. The son claim; they refute this position in Homicide. biophobic social scientist was also, according to Their position is that for stepparents the bond that detractors of Tooby and Cosmides position, a prevents parents in general from hurting their strawperson. Many researchers claimed that children is weaker, and therefore, some stop there was more attention given to the biological mechanisms have reduced function. They are underpinnings of culture and learning than Tooby therefore not arguing that biological parents can- and Cosmides acknowledged. On the other hand, not kill their offspring or that stepparents in gen- the lip service to such biological factors with no eral will hurt their stepchildren. At the population place for any specific theory, no methodology that level, the Cinderella effect is still a statistically accounted for the relevance of such factors, and a documented phenomenon. general reflexive dismissal of all attempts to add functional approaches to scientific explanation Cosmides and Tooby: Human Universals was exactly what Tooby and Cosmides were and Interpersonal Competition targeting. Most evolutionary psychologists have John Tooby and Leda Cosmides were recently met these alleged straw men among both editors awarded the lifetime achievement award by the and reviewers, as well as colleagues. Actually, to HBES. They may be considered the most influen- some degree, some evolutionary psychologists tial theoreticians within EP and probably the foun- share SSST features in their thinking about devel- ders of the basic theory through their theoretical opment, with regard to behavioral genetic papers in the 1980s and early 1990s. While some findings. of the theoretical claims such as the There was no dismissal of learning nor culture, non-adaptiveness of personality differences as relevant and important phenomena in this might not be accepted by the entire field, their essay. Only a very clear caveat that learning is work on human universals sets the stage for a not an explanation without further specification of social-cognitive evolutionary psychology situated what exactly it is that one means. It is very safely within normal psychological science meth- unlikely that Skinner would have disagreed with odology. At the same time, their attacks on the their critique of the simple incantation of general Standard Social Science Model (SSSM) created a learning by general mechanisms without further certain distance to social psychology and social evidence and description of the mechanism, Founders of Evolutionary Psychology 7 including the possible evolutionary history of the relevant for detecting social contract rule breaking learning mechanism. This essay largely func- (Cosmides 1989). tioned as a call to arms for evolutionary psychol- It is not particularly important what social con- ogists, laying the foundation for a more stringent tract rule one tests; it can be made up or a familiar science of both learning and culture from an evo- social rule in participants’ culture. If the rule to be lutionary perspective. As such, one might note tested is a social contract rule and there are poten- that it was considered more convincing in the tial cheaters to be detected, people solve the long run by psychologists than by Wason selection task much more frequently. anthropologists. Note that from a logical perspective, the problem and solution are the same. Consider this example: Four cards representing Solving the Wason Selection Task four people in a seedy bar. The rule is that only The Wason selection task is a logical problem in those who are older than 18 may drink beer. The which people are shown four cards. They have a cards display the age (either above or below 18) numeral printed on one side and a letter on the on one side and what the person is drinking (either other side. They are placed on the table in front of soda or beer) on the other. The four cards show the participant. Two of these cards are dealt with [Soda] [Beer] [Above 18] [Below 18]. Who do the numeral facing up; the other two show the you want to check, to test the rule? While most letters, for example, [7][H][3][D]. The participant people want to check and confirm [D] and is then given a rule for the cards and asked which [7] above, that solution is no longer interesting. card(s) to turn to test the rule. In this case the rule Now most people want to find cheaters. Most is behind every [D], there is a [7]. The question people want to see whether the person below then is: Which cards would you turn? Typically, 18 is drinking beer (falsification not confirmation) people are governed by their confirmation bias. and how old the beer drinker is (yet again and They therefore flip over [7] and [D], in both cases contrary to what one does in the non-social to confirm the rule rather than attempting to falsify cheating context, in order to check whether the it. This phenomenon occurs irrespective of intel- person is too young). ligence and education. Furthermore, when people In other words, we become natural Popperian have learnt the solution of by heart, they will in falsifiers and ditch our normal human confirma- some cases still provide erroneous explanations, tion bias problems if someone might be breaking a yet again reverting to their confirmation social contract. This applies to the majority of bias – which illustrates how strong this tendency people, and it is not dependent upon familiarity is. The correct answer, which is not typically the or cultural context. Finally and most importantly, human response, is to flip over [3] to find a [D], it was not predicted by any other theory. Perhaps and the most difficult, to flip over [D] to not find a most surprisingly, there is probably dedicated [7]. neural circuitry involved in cheater detection It may seem strange, given how much more (Stone et al. 2002) – which in turn provided sup- attention sexual research gets, that an abstract port for the modular approach. cognitive bias test was probably the single empir- Why should we be good at discovering ical research finding that paved most of the way cheaters? We are hyper-social intelligent animals, for EP as a specific scientific research program. both dependent upon and in active competition While Tooby and Cosmides have continued their with other humans. We are able to make social research into coalitional, innate, and evolved psy- rules and break these same rules. Being naïve chology (including topics from war to incest about rule breakers is not a viable evolutionary avoidance), it all started with a groundbreaking strategy. The finding that a module for solving a finding: that human limitations in solving logical specific, adaptively relevant problem could make problems, documented in a multitude of studies, us better at solving generally unsolvable logical vanished once they were made ecologically problems was groundbreaking. The immense 8 Founders of Evolutionary Psychology creativity of these founders, and their ability to Buss: Individual Differences and Mate succinctly formulate the basic theoretical logic Preferences underlying many psychological problems, has Mate choice is a fundamental aspect of evolution, resulted not only in fundamental theoretical and mates vary. There are individual differences papers: research into other social, coalitional cog- among potential mates, and we choose among nitive processes, such as welfare-benefit ratios these potential sexual partners either to mate and race perception followed from the same inter- romantically for life or for the sexual thrill of the est in the underlying evolved adaptations and moment. If someone were to steal our romantic provided our science with findings and explana- partner, it would hurt us, both emotionally and tory principles that were both original and through possible fitness costs. All of these areas counterintuitive. that might seem very familiar to anyone with an interest in evolutionary psychology have been Strategic Modeling pioneered by David Buss. And beyond important Together with Irvin DeVore, John Tooby wrote a theories such as sexual strategy theory, with David classic on why human evolutionary psychology Schmitt, and error management theory with must take into account specific human evolution. Martie Haselton maybe Buss is the researcher While many earlier approaches to human evolu- that has provided the field with the broadest and tionary behavioral science were to a large degree deepest empirical basis. This has also aided the comparative, Tooby and DeVore (1987) point out communication of evolutionary psychology to the that in order to study the species-specific adapta- rest of academic psychology. For the field, his tions of humans, such an approach will be textbook and The Handbook of Evolutionary Psy- severely limited. Evolutionary psychology is chology have become landmarks, improving the therefore to a much lesser degree comparative in teaching and uniting the field. its general approach than sociobiology was or to the degree that more biological approaches to Cross-Cultural Mate Preferences human psychology often are. While homologous Cross-cultural research has not been typical in structures exist, when considering human nature, social sciences in general or psychology specifi- it is primarily relevant and even imperative to cally. While critics of merely considering West- consider specific hominin evolution and selection, ern, Educated, Industrialized, Rich, and especially those traits that are unique to humans. Democratic (WEIRD) populations have made This gem is not as often cited as it ought to be but important corrections to the generalizability of provides insights into how early evolutionary psy- psychological research, it is worth noting that chology theorizing differed from other evolution- from early on evolutionary psychology has been ary approaches to both animal and human oriented toward cross-cultural studies and more so behavior. While many academics believe that than many other areas of psychological research. humans are freed from the animal shackles of One of the most groundbreaking of these evolu- evolution, Tooby and DeVore suggest that the tionary cross-cultural studies was David Buss’ complexities of proximate mechanisms hide the mammoth collaborative study of mate choice in fact that the ultimate function has not changed. 37 cultures. Strategic modeling of complex proximate mecha- Building on his early work on mate choice nisms is therefore a tool to reduce such complex- (Buss 1985), and inspired by Don Symons’ ity, which reveals how they are “adaptively (1979) work on human sexuality and human uni- patterned.” Note that while this chapter is primar- versals, Buss started collecting one of the largest ily a contribution to paleontological modeling of international data sets at the time. While some hominin species, the principle strategic modeling have criticized the cultural variance and national they suggest is most relevant as a metatheory of sample sizes, this is a landmark study, with few evolutionary and behavioral analyses of function studies in psychology, and especially cross- and specific human evolution. Founders of Evolutionary Psychology 9 cultural studies, coming close in influence and adaptive individual differences, including citations. frequency-dependent selection and their concept Buss (1989) reported several cross-culturally of reactive heritability (where, e.g., some traits are robust similarities between the sexes. For exam- more efficient in specific bodies or in concert with ple, both men and women are interested in intel- other traits and thus may become more expressed ligence and agreeableness traits, especially in under the right and adaptive circumstances). long-term relationships. On the other hand, stable A full understanding of human nature demands male-older findings, where both sexes seem to that we also understand the evolution of stable agree that he should be older than her, greater differences in fitness-relevant behaviors, as male interest in female physical attractiveness, defined by traits. Also, trait psychologists have and greater female interest in male financial pros- suggested that evolutionary psychology has to pects suggested evolutionarily predictable sex dif- address the question of how the five major per- ferences in partner preferences. These original sonality traits of openness, conscientiousness, findings have been reproduced repeatedly and extroversion, agreeableness, and neuroticism have proven to be stable across cultures as well have evolved (Nettle 2011). David Buss as within cultures across time. Age preferences pioneered the area of evolutionary personality have also received attention in the last few years. psychology, which has been slow to gain momen- While many critics of evolutionary psychology tum in empirical data collection, but in recent have attempted to challenge these findings on years’ has increased with interest in life history human universal mate preferences, they appear approaches. Future empirical testing is still much to be among social psychology’s most replicated needed for evolutionary personality psychology conclusions. data collection to catch up with theory generation. At the moment, we have different approaches Evolutionary Personality Psychology within EP that consider either how individual There are two major approaches to the science of differences in life histories may provide testable psychology reflected in many areas of research. In predictions about behavior, but also theories of some disciplines and theories, one considers how the five major personality traits are a result human universal nature, and the theories and find- of specific evolutionary processes, including ings are considered relevant for all humans. Such selective neutrality, frequency-dependent selec- areas include learning psychology and to a large tion, and mutation-selection balance. We need degree social psychology in general. Personality more work testing different hypotheses. At the psychology, on the other hand, considers individ- same time, from an evolutionary personality psy- ual differences. This is one of the interesting areas chology perspective, it would be odd if these of open disagreement among the founders of value-laden descriptions of others that make up EP. The basic formulation of EP by Tooby and the basis of traits had not been relevant for selec- Cosmides (1990a) focuses explicitly on human tion. Noise or adaptive? We still do not know. This universals and does not even consider sex differ- area still needs more evidence. ences in their study of evolved mental mechanisms. As mentioned above, EP is in its original Sexual Strategy Theory formulation by Tooby and Cosmides, largely a Formulated with David Schmitt, sexual strategy theory of the minds of both men and women, theory (SST) is one of the most influential equally. Tooby and Cosmides (1990a) were quite approaches to the understanding of human sexual explicit about personality and other individual behavior (Buss and Schmitt 1993). SSTstarts with differences not being key areas of study from an the general principles of Trivers’ (1972) parental EP or adaptationist perspective. There is therefore investment theory, but specifies the theory for a certain shift in focus in different directions even human women and men and our species-typical within mainstream EP. On the other hand, they adaptive sexual problems. An important contribu- suggested mechanisms that could explain tion of the theory is the attention given to mating 10 Founders of Evolutionary Psychology context as well as sex: Men and women have following five adaptive problems need to be different preferences and behavior in short-term solved by women in the adaptive problem of and long-term mating contexts. This lays the acquiring the best possible long-term relationship foundation for several predictions about how (Buss and Schmitt 1993): discerning men who are men and women in short-term and long-term mat- (1) able and (2) willing to invest resources in her ing situations will act or display preferences. and her children on a long-term basis, (3) identify- Women and men have engaged in both long- ing men who will be good fathers, (4) identifying term and short-term sexual relations throughout men who are willing and able to commit, and evolutionary history and been selected for these (5) identifying men who will be both able kinds of behavior if the benefits outweigh the (formidable) and willing (aggressive) to defend average cost. But each context presents different them against other men. adaptive problems for the two sexes. Due to dif- The evolutionary perspective suggested that ferences in minimal parental investment and pos- men and women have been selected so that they sibilities to benefit from multiple matings, men on average will solve the adaptive problems effec- will have greater interest in short-term sex than tively when engaging in short-term sex or long- will women. This exemplifies one adaptive prob- term relationships. While the word strategy might lem difference, but there will be predictable sim- be confusing, the strategy is the evolved, effective ilarities and differences between men and women solution to the adaptive problems, the mental in all four combinations of sex and context. Buss adaptations solving context specific adaptive and Schmitt (1993) list the following four adap- problems, with no conscious goal being assumed. tive problems for men for either a long-term rela- Beyond being a very influential theoretical paper, tionship or short-term sexual encounters: it also provided data that tested direct predictions about, for example, male interest in both long- Long-term relationships: (1) discerning reproduc- term and short-term relationships and interest in tive value, (2) ensuring paternal certainty, sexual variety. (3) identifying good mothers, and (4) identify- SST met with criticism from mainstream social ing willingness to commit psychology. One claim was that our sexual psy- Short-term sexual encounters: (1) acquiring a chology is inherently monomorphic, but cultural large number of partners, (2) discerning who structures will cause differentiation. Therefore, is sexually accessible, (3) discerning fertility, detractors of SST believed one would not find and (4) minimizing any investment and similar results as in the American sample in commitment other more gender egalitarian nations. Such criticism must be testable in order to be scientific; one Note that reproductive value is very important cannot make such claims and not accept findings for long-term relationships, while current fertility from the world’s most gender egalitarian nations is relevant for short-term relationships. Similarly, as not relevant. Since 1993, hypotheses from SST minimizing investment is not as relevant for a have been tested internationally; in some cases, monogamous long-term relationship. The ability there are differences – with both smaller and and willingness to commit in long-term relation- larger sex differences being reported from more ships will not differ between the sexes and should gender egalitarian nations than the USA. In gen- rank high among partner preferences for both eral, though, these results have supported SST as sexes. the best theory for generating hypotheses about Women’s reproductive success has not been modern human sexual behavior and sex and con- constrained by access to sex, but rather access to text differences in preferences. For example, resources and maybe genes of the men that are direct tests suggest that one finds almost exactly interested in investing in them and their offspring, the same results for the original SST findings in a both here and now and on a long-term basis. The more gender egalitarian Norwegian sample. Founders of Evolutionary Psychology 11

Jealousy is not detectable with continuous measures, It is simple: Imagine that there is no parental maybe due to ceiling effects. At the same time, investment, no long-term relationships, and full continuous measures are considered more mean- knowledge of who both parents are. In this sce- ingful by some critics, and some suggest the sex nario there is no jealousy. Now, change a few difference is merely a methodological artifact. things: Add father investment with no or low Recent work found that when randomly distribut- paternal certainty. Is it then possible that male ing either continuous or forced choice question- sexual jealousy would not evolve? Men are naires in the same population, there was no among 5 % of mammals in which fathers invest difference between the two methodologies in assumed offspring. Concealed conception (Bendixen et al. 2015). This study also found results in less than complete paternity certainty, that, rather than there being smaller sex differ- despite different cultural inventions that attempt ences in jealousy in more gender egalitarian to control female sexuality. What would happen to nations, the effect sizes are larger, probably driven the more protective and skeptical or jealous men by greater expected male investment as proposed compared to the men who are naïve and uncaring by Buss et al. (1992). Another criticism is that sex about their partner’s sexual escapades? The same differences in jealousy might only hold for young, is the case for women: What would happen to heterosexual participants. However, finding that women who were uninterested in their partner’s postmenopausal female partners elicit less jeal- interest in investing in their joint children? Rather ousy is congruent with evolutionary theory. than attempt to prove how sex differences in jealousy evolved, one might turn that around: How Considering Future Developments could these specific types of interest in fatherhood Evolutionary psychology has developed during or future resource investment not evolve? And the almost 35 years since the first formulations what feedback mechanism could help us learn of the evolutionary psychology basic theory, not the effects? Men would never get to know the just in general acceptance among academics and negative effect. If women did see the effect, it inclusion in mainstream psychology textbooks would certainly be too late. but also as a theory. In the beginning, the focus Prior to Buss’ original work on jealousy, psy- was largely on human universals, but there has chologists were not aware of sex differences in been a clear shift toward considering individual jealousy: men being more distressed by sexual differences in both normal personality (Buss and infidelity than emotional infidelity than women Penke 2015) as well as psychopathology (Del are (Buss et al. 1992). It is worth noting that it is Giudice 2014; Kennair 2011) and the effects of the interaction that is relevant by testing whether cultural differences, highlighted by the work of men, relative to women, find sexual infidelity David Schmitt. In the last few years, greater more distressing than emotional infidelity. While emphasis has been placed on life history theory the logic of the evolutionary theory seems con- (Del Giudice et al. 2015), primarily as an expla- vincing, there have been several challenges to the nation of individual differences, but also psycho- theory. First, that one sort of infidelity (either pathology. Furthermore, there is a continued emotional or sexual) would elicit the conclusion interest in evolutionary developmental science. that the other form had occurred, so that there was All of these areas need empirical and theoretical not really a sex difference. This was called the developments to be tempered with knowledge double-shot theory. It is simple to test: One from the field of behavioral genetics in order to changes the question from “what is most fully come to fruition. While many researchers are distressing, sexual or emotional infidelity?” to now considering how unstable childhood envi- “if both sexual and emotional infidelity have ronments predict instability in personality traits occurred, which type is most distressing?” In or behavior of young adults, it is worth noting this double-shot scenario, sex differences persist. that behavioral genetics research suggests that Another challenge is that the stable sex difference parent-offspring similarities in general are due 12 Founders of Evolutionary Psychology more to genetics rather than environmental ▶ George Williams influences. ▶ Homicide The many students of the founders have also ▶ Jealousy started making large contributions in their own ▶ Leda Cosmides and John Tooby right, both empirically and theoretically, and ▶ Life History Theory many of these may be considered part of the ▶ Martin Daly and Margo Wilson foundations of EP. Two select examples: Martie ▶ Mate Preferences Haselton and David Buss’s(2000) error manage- ▶ Modularity ment theory, is generating both supportive and ▶ Reliability, Efficiency, and Economy critical research within EP. Also, research on ▶ Richard Dawkins race perception, originally developed by Kurzban ▶ Robert Trivers et al. (2001), is providing an evolutionary base for ▶ Sexual Strategies Theory conceiving of race as merely one of many arbi- ▶ Sociobiology trary and therefore inherently malleable ▶ Standard Social Science Model out-group cues. ▶ Strategic Modeling ▶ The Adaptationist Program ▶ The Adapted Mind Conclusions ▶ The Controversies in Evolutionary Psychology ▶ The Extended Phenotype These five founders of EP as a specific research ▶ The Handbook of Evolutionary Psychology program have established an evolutionary-based ▶ The Selfish Gene approach to psychological research, which over ▶ Wason Selection Task the last three decades has become part of main- ▶ Young Male Syndrome stream psychological science after initially being considered both politically and scientifically sus- pect. At the same time, there have obviously been References many other influential figures in the field who have inspired the development of both evolution- Bendixen, M., Kennair, L. E. O., & Buss, D. M. (2015). ary psychology research and theory, both by chal- Jealousy: evidence of strong sex differences using both lenging and developing the original formulations. forced choice and continuous measure paradigms. Per- – As such, the area of study has been influenced by sonality and Individual Differences, 86(0), 212 216. doi:http://dx.doi.org/10.1016/j.paid.2015.05.035. critics, students, and colleagues working around Buss, D. M. (1985). Human mate selection: opposites are the globe in collaboration and competition. sometimes said to attract, but in fact we are likely to marry someone who is similar to us in almost every variable. American Scientist, 73,47–51. Buss, D. M. (1989). Sex differences in human mate pref- Cross-References erences: evolutionary hypotheses tested in 37 cultures. Behavioral and Brain Sciences, 12(1), 1–49. ▶ Adaptation and Natural Selection doi:10.1017/S0140525X00023992. ▶ Anxiety Buss, D. M. (1995). Evolutionary psychology: a new par- ▶ adigm for psychological science. Psychological Anxiety Cinderella Effect Inquiry, 6(1), 1–30. ▶ Cheater Detection Buss, D. M., Larsen, R. J., Westen, D., & Semmelroth, ▶ Cinderella Effect, The Controversies in Evolu- J. (1992). Sex differences in jealousy: evolution, phys- iology, and psychology. Psychological Science, 3, tionary Psychology – ▶ 251 255. doi:10.1111/j.1467-9280.1992.tb00038.x. David Buss Buss, D. M., & Penke, L. (2015). Evolutionary personality ▶ Environment of Evolutionary Adaptedness psychology. In M. Mikulincer, P. R. Shaver, ▶ Evolutionary Clinical Psychology M. L. Cooper, & R. J. Larsen (Eds.), APA handbook ▶ Evolutionary Personality Psychology of personality and social psychology, volume 4: personality processes and individual differences ▶ Field of Evolutionary Psychology Founders of Evolutionary Psychology 13

(pp. 3–29). Washington, DC: American Psychological Kurzban, R., Tooby, J., & Cosmides, L. (2001). Can race Association. be erased? Coalitional computation and social catego- Buss, D. M., & Schmitt, D. P. (1993). Sexual strategy rization. Proceedings of the National Academy of Sci- theory – an evolutionary perspective on human mating. ences, 98(26), 15387–15392. doi:10.1073/ Psychological Review, 100(2), 204–232. doi:10.1037/ pnas.251541498. 0033-295X.100.2.204. Marks, I. M., & Nesse, R. M. (1994). Fear and fitness: an Cosmides, L. (1989). The logic of social exchange: has evolutionary analysis of anxiety disorders. Ethology natural selection shaped how humans reason? Studies and Sociobiology, 15(5–6), 247–261. doi:http://dx. with the Wason selection task. Cognition, 31(3), doi.org/10.1016/0162-3095(94)90002-7. 187–276. doi:http://dx.doi.org/10.1016/0010- Nettle, D. (2011). Evolutionary perspectives on the five- 0277(89)90023-1. factor model of personality. In D. M. Buss & Cosmides, L., & Tooby, J. (1987). From evolution to P. H. Hawley (Eds.), The evolution of personality and behavior: evolutionary psychology as the missing individual differences (pp. 5–28). New York: Oxford link. In J. Dupré (Ed.), The latest on the best : essays University Press. on evolution and optimality (pp. 276–306). Cambridge, Pinker, S. (1997). How the mind works. Harmondsworth: MA: The MIT Press. The Penguin Press. Daly, M., & Wilson, M. (1988). Homicide. Hawthorne: Stone, V., Cosmides, L., Tooby, J., Kroll, N., & Knight, Aldine de Gruyter. R. (2002). Selective impairment of reasoning about Del Giudice, M. (2014). An evolutionary life history social exchange in a patient with bilateral limbic system framework for psychopathology. Psychological damage. Proceedings of the National Academy of Sci- Inquiry, 25(3–4), 261–300. doi:10.1080/ ences, 99(17), 11531–11536. 1047840X.2014.884918. Symons, D. (1979). The evolution of human sexuality. New Del Giudice, M., Gangestad, S. W., & Kaplan, H. S. York: Oxford University Press. (2015). Life history theory and evolutionary psychol- Tooby, J., & Cosmides, L. (1990a). On the universality of ogy. In D. M. Buss (Ed.), The handbook of evolutionary human nature and the uniqueness of the individual: the psychology (2nd ed., pp. 88–114). New York: John role of genetics and adaptation. Journal of Personality, Wiley & Sons, Inc.. 58(1), 17–67. doi:10.1111/1467-6494.ep8970991. Hamilton, W. D. (1964a). The genetical evolution of social Tooby, J., & Cosmides, L. (1990b). The past explains the behaviour. I. Journal of theoretical biology, 7(1), 1–16. present. Ethology and Sociobiology, 11, 375–424. doi:http://dx.doi.org/10.1016/0022-5193(64)90038-4. doi:10.1016/0162-3095(90)90017-Z. Hamilton, W. D. (1964b). The genetical evolution of social Tooby, J., & Cosmides, L. (1992). The psychological foun- behaviour. II. Journal of Theoretical Biology, 7(1), dations of culture. In J. H. Barkow, L. Cosmides, & 17–52. doi:10.1016/0022-5193(64)90039-6. J. Tooby (Eds.), The adapted mind: evolutionary psy- Haselton, M. G., & Buss, D. M. (2000). Error management chology and the generation of culture. New York: theory: a new perspective on biases in cross-sex mind Oxford University Press. reading. Journal of Personality and Social Psychology, Tooby, J., & DeVore, I. (1987). The reconstruction of 78(1), 81–91. doi:10.1037/0022-3514.78.1.81. hominid behavioral evolution through strategic model- Kennair, L. E. O. (2002). Evolutionary psychology: an ing. In W. G. Kinzey (Ed.), The evolution of human emerging integrative perspective within the science behavior: primate models. Albany: SUNY Press. and practice of psychology. The Human Nature Review, Trivers, R. L. (1972). Parental investment and sexual selec- 2,17–61. tion. In B. Cambell (Ed.), Sexual selection and the Kennair, L. E. O. (2007). Fear and fitness revisited. Journal descent of man: 1871–1971 (pp. 139–179). Chicago: of Evolutionary Psychology, 5(1), 105–117. Aldine Press. doi:10.1556/JEP.2007.1020. Trivers, R. L. (1974). Parent-offspring conflict. American Kennair, L. E. O. (2011). The problem of defining psycho- Zoologist, 14(1), 249–264. doi:10.1093/icb/14.1.249. pathology and challenges to evolutionary psychology Tybur, J., Miller, G., & Gangestad, S. (2007). Testing the theory. In D. M. Buss & P. H. Hawley (Eds.), The controversy: an empirical examination of evolution of personality and individual differences adaptationists’ attitudes toward politics and science. (pp. 451–479). New York: Oxford University Press. Human Nature, 18(4), 313–328. doi:10.1007/s12110- Ketelaar, T., & Ellis, B. J. (2000). Are evolutionary expla- 007-9024-y. nations unfalsifiable? Evolutionary psychology and the Wilson, M., & Daly, M. (1985). Competitiveness, risk lakatosian philosophy of science. Psychological taking, and violence: the young male syndrome. Ethol- Inquiry, 11(1), 1–21. doi:10.1207/ ogy and Sociobiology, 6(1), 59–73. doi:10.1016/0162- S15327965PLI1101_01. 3095(85)90041-X.