Evolutionary Behavioral Sciences © 2018 American Psychological Association 2019, Vol. 13, No. 2, 127–157 2330-2925/19/$12.00 http://dx.doi.org/10.1037/ebs0000127 Why Is Age So Important in Human Mating? Evolved Age Preferences and Their Influences on Multiple Mating Behaviors

Daniel Conroy-Beam David M. Buss University of California, Santa Barbara University of Texas, Austin

Evolutionary theorizing suggests that chronological age, because it is so strongly linked with key reproductive qualities like fertility, should be an exceptionally consequential variable in mate selection. We review voluminous evidence for mate preferences for age and the substantial and varied behavioral sequelae of those preferences. These include (a) in actual marriage decisions, men choose younger wives, and women choose older husbands, on average in all of the dozens of cultures studied; (b) in personal advertisements, men and women seek partners consistent with their expressed age preferences; (c) chronological age determines number of “hits” received in online dating services; (d) the age of potential bride influences the amount of money spent on premarriage customs; (e) men’s mate retention effort, including commitment manipu- lation, resource provisioning, and intrasexual threats, is significantly predicted by the wife’s age; and (f) chronological age is an important sex-linked cause of divorce. The far-reaching ramifications of age also extend to (g) tactics of intrasexual competition, (h) predictors of mate value discrepancies, (i) victims of sex crimes, and (j) prostitution patterns. Finally, chronological age predicts (k) probability of remarriage, and (l) the age gap between grooms and brides upon remarriage. We synthesize evidence from diverse methods, across different cultures, and over time spans of centuries. Massive converging evidence provides a powerful, yet complex, understanding of the evolu- tionary importance of age in multiple mating outcomes over the human life span.

Public Significance Statement We review the voluminous evidence that people express ideal preferences for the age of their potential mate and act on these preferences in mate selection. This review speaks to an ongoing debate in the human mating literature concerning the importance of ideal preferences for real mating behavior. Further, it serves to highlight the many domains of life into which mating spreads its influence.

Keywords: age, mate preferences, mate selection, mating behavior, evolutionary psychology

Age is a peculiar, yet singularly important, people can be arrayed on this variable. It carries attribute of humans. Everyone has an age, so all special social significance in many contexts— the benevolent or condescending treatment of youth; the social hierarchies constructed on “re-

This document is copyrighted by the American Psychological Association or one of its allied publishers. specting elders;” the social segregation by age This article is intended solely for the personal use of the individual user and isThis not to be disseminated broadly. article was published Online First August 9, 2018. in most or all cultures; the social invisibility of Daniel Conroy-Beam, Department of Psychological and the young or old depending on culture and con- Brain Sciences, University of California, Santa Barbara; text; and its frequent occurrence in everyday David M. Buss, Department of Psychology, University of discourse, ranging from exhorting people to Texas, Austin. We thank Kelly Asao, Leif Kennair, Frank Mann, Anna “act their age” to derogatory comments about Sedlacek, and Joy Wyckoff for helpful comments on an people being either immature or “over the hill.” earlier version of this article. No one, it seems, is indifferent to age. Correspondence concerning this article should be ad- From an evolutionary perspective, age takes dressed to Daniel Conroy-Beam, Department of Psycholog- ical and Brain Sciences, University of California, Santa on special conceptual significance because so Barbara, CA, 93106. E-mail: [email protected] many elements that contribute to mate value

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covary with age. Among them are pubescence, documented worldwide across cultures and over fertility, senescence of reproductive organs, time, are meaningless psychological quirks; (b) physical size, emotional maturity, social status, that people who adopt tactics of mate attraction, and abilities to acquire reproductively relevant tactics of derogation of competitors, and tactics resources—life history variables of profound of mate retention that correspond to the per- importance. These age-graded elements are core ceived mate preferences of the opposite sex are to association value, such as kin value and co- deluded because those tactics lack efficacy in alitional value. Perhaps most important, they attracting mates or besting mating rivals; and (c) are core to mate value and make age central to that humans are the sole known sexually repro- human mating (Symons, 1979; Williams, 1975). ducing species, alone among the millions of Empirical evidence across research labs, sexually reproducing species on Earth, that lack methods, cultures, and time establish age as a functional preferences for potential mating part- key variable in mate preferences and mate se- ners. lections. That people readily and reliably track Here we provide an in-depth examination of and store their age makes age an empirically the role of mate preferences in driving human tractable variable. Age has all of the features of behavior by focusing on ideal mate preferences a model variable for studying mate preferences for age. Several foundational articles have es- and mate choice more broadly. Yet age has tablished that age preferences act to guide hu- received relatively little attention from mating man mate choice (e.g., Buss, 1989; Kenrick & researchers compared to variables like physical Keefe, 1992). In the more than a quarter century attractiveness, for which there are hundreds of since these articles, numerous empirical find- empirical studies. ings have been published, so it is timely to do a Cross-cultural research demonstrates that hu- stock-taking and more extensive conceptual in- mans appear to have universal mate prefer- tegration. We expand on these classic articles in ences, including those for the age of potential two critical ways. First, we review the volumi- mates (e.g., Bech-Sorensen & Pollet, 2016; nous but previously unexamined evidence, ac- Buss, 1989; Kenrick & Keefe, 1992). These cumulated prior to and since the publication of preferences were originally hypothesized to these original articles, from across cultures and function in guiding people to adaptive mate across centuries, that bears on the hypothesis choices—a fundamental domain of life for sex- that humans select mates based on ideal prefer- ually reproducing organisms. However, they ences for age. also should have implications for a wide array Second, we expand on prior discussions of of downstream behavioral outcomes, such as age preferences by reviewing bodies of litera- tactics of attraction, selection of mates as a ture that connect age preferences to a wide array function of mate value, determinants of mate of real-world outcomes. These include self- retention, likelihood of experiencing sexual ha- reported ideal preferences, personal advertise- rassment, probability of divorce, and a host of ments, and marriage data but also the effects of other important life outcomes. age preferences on gift giving, prostitution, re- As a secondary issue, the study of age mate lationship dissolution, mate guarding, criminal preferences and their consequences have a crit- behavior, remarriage patterns, and deception ical bearing on a recent debate that has emerged (see Figure 1). This synthetic review under- in the scientific literature. Some have chal- scores the broad importance of mating and mate This document is copyrighted by the American Psychological Association or one of its allied publishers. lenged the view that mate preferences are con- preferences to human behavior. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. sequential in driving mating decisions. They To frame this treatment, we first discuss the have advanced the view that mate choice is hypothesized functions of preferences broadly, more or less random with respect to preferences and then specifically within the mating domain. (e.g., Eastwick, Luchies, Finkel, & Hunt, 2014; We then move into theoretical background con- for counter arguments and evidence, see Li & cerning the importance of age before reviewing Meltzer, 2015; Li et al., 2013). If this view were empirical evidence establishing that males and correct, it would undermine the scientific im- females have distinct preferences for ages in portance of mate preferences and would lead particular mates. Finally, we examine this key logically to three surprising conclusions: (a) question: Do age mate preferences drive actual that consensually expressed mate preferences, mating behavior in its many domains? AGE PREFERENCES IN MATES 129

Figure 1. The broad impacts of age mate preferences.

Why Have Preferences? environmental input. People can learn to enjoy bitter or spicy flavors depending on what is Preferences are effective tools for solving available in their local environment—mate decision making problems. Across domains, or- preference mechanisms also have important en- ganisms face problems wherein they must select vironmental inputs, albeit different ones from among alternatives. Consider food choice. All those of food choices. organisms must extract nutrients and calories Preference mechanisms need several features from their environments. But not all items that to serve as effective decision-making adapta- could be eaten contribute to this end, and some tions. Preferences first must map onto the ben- actively work against it. Evolved food selection efit structure present in the real-world alterna- preferences are effective adaptations that proba- tives. Habitat preferences provide a good bilistically guide organisms to ingest nutritious and energy-provisioning foods and to avoid in- example. Potential habitats vary on a variety of This document is copyrighted by the American Psychological Association or one of its allied publishers. gesting substances teaming with toxins or harm- dimensions relevant to fitness. Habitats must be This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. ful microorganisms (Rozin, 1976). All known of a suitable temperature for the organism in species show marked food preferences that map question. Habitats should be relatively devoid onto the nutrients available in their environ- of predators and rich in prey. They should offer ments. For instance, humans have strong pref- prospect (resources) as well as refuge (places to erences for fats and sugars (important energy see without being seen Orians & Heerwagen, sources) as well as nutrient-dense savory and 1992). An effective decision-making psychol- salty foods; bitter and sour flavors are aversive ogy would generate preferences that attract or- because they are associated with dangerous and ganisms to habitats that contain fitness- toxic foods (Krebs, 2009; Rozin, 1976). Of promoting elements (temperate, safe, with course, these preferences are not insensitive to prospect and refuge), repel them from fitness- 130 CONROY-BEAM AND BUSS

costly habitats (extreme, predator-packed cli- births, divorces, and deaths happen to be among mates with few resources and little shelter), and the highest fitness-impact events in an individ- allow them to disregard fitness irrelevant infor- ual’s life. We suggest these facts, taken to- mation (e.g., local cloud shape). Additionally, gether, make age a uniquely powerful window the strength of preferences for a dimension into the complex dynamics and nuances of mate should be correlated with the fitness impact of preferences, mate selection psychology, and its the dimension: Those dimensions that affect sequelae. fitness the most should be those that most affect habitat selection. Age Is an Important Cue to Mate Value There are strong conceptual reasons to expect mating to be a domain governed by mate pref- The importance of age stems from a simple, erences. First, through the lens of selection, fundamental fact: Time and energy are finite choosing a mate is one of the most important resources. Organisms must allocate some of decisions a sexually reproducing organism can their limited time and energy to the evolutionary make. Reproduction cannot occur without this bottom line: reproduction. However, before an vital decision. Potential mates vary on dozens of organism can reproduce, it must first complete dimensions, such as health, size, shape, person- several other tasks. A successful organism must ality, social status, kin ties, and coalitional alli- stay alive against bodily wear and tear and ances. They also vary on cost-inflicting attri- pathogenic infection. A surviving organism butes such as mutation load, parasite load, and then must find a suitable mate with whom to aggressive temperament. Poor mate choice reproduce. These tasks require constructing could jeopardize an individual’s entire repro- psychological and physiological systems that ductive career; good mate choice could greatly perceive, act, learn, digest, and move. Building enhance it. Choosing a benefit-bestowing mate and operating these systems requires organisms and avoiding a cost-inflicting mate, in short, has to forage for energy and nutrients from the enormous fitness consequences, so selection environment. Finally, successfully reproducing should strongly favor mate preference adapta- in highly altricial species such as our own re- tions. A large research area confirms this expec- quires providing some time and energy to allow tation for nonhuman organisms (e.g., Thornhill one’s offspring to survive and reproduce. The & Alcock, 1983) and for humans (Buss, 2015). better an organism accomplishes these nonre- The extent to which preferences guide actual productive processes, the more effectively that mating behavior, the circumstances in which it organism can ultimately reproduce. Organisms does so, and which individuals are best and least therefore face a fundamental tradeoff: An or- able to translate their desires into successful ganism can invest time and energy in immediate mate selections has been less well studied. reproduction or they can delay reproduction and invest energy in other processes, with the po- Why Age Is Vitally Important in tential for more or higher quality reproduction Human Mating in the future. An inevitable consequence of these “life his- Mate preferences for age provide a good win- tory” tradeoffs is a particular maturation sched- dow into understanding the potentially far- ule. Slowly developing species like our own reaching consequences of mate preferences for have to spend a substantial period of time in- This document is copyrighted by the American Psychological Association or one of its allied publishers. two key reasons. The first is theoretical. Age is vesting energy in development and maintenance This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. monumentally important to mate selection be- rather than reproduction and our lifespans are cause it is central to mate value—the net fitness consequently characterized by periods of ex- benefits a mate affords. The second is empirical. tended juvenility. During these juvenile periods, Age is an eminently tractable variable and reli- our bodies—and brains, for humans—grow ably recorded. People tend to keep close track rapidly. The demands of this rapid development of age in their personal lives. Importantly, the preclude investing in reproduction, and juve- larger society also seems to believe age is im- niles consequently remain infertile and sexually portant, because age is widely recorded in pub- uninterested. For humans, this is a critical time lic documents such as births certificates, mar- of learning. People dedicate enormous time and riage licenses, and death certificates. Marriages, energy to learning a language, learning social AGE PREFERENCES IN MATES 131

divisions and hierarchies, and, crucially, learn- This natural senescence creates trends of ex- ing the knowledge and skills necessary to nav- treme importance to mate selection. Both sexes igate their social and physical environments. experience a gradual decline in health late in These young humans have little time, energy, or life—a decline critical to mate value. Males and ability to dedicate toward foraging for them- females also have somewhat different senes- selves and are consequently extremely depen- cence curves on components that contribute to dent on investment from others. mate value. Males experience a decline in their This extended developmental period is ended resource productivity as their increased skill and by a relatively abrupt entrance into reproductive knowledge gradually fails to compensate for investment. For humans, this is marked by pu- decreasing health and physical prowess. Female berty, at which a host of reproductive charac- fertility also begins a decline after its peak be- teristics emerge—menstrual cycling, breast de- fore totally ceasing at menopause. The reasons velopment, and increased fat deposition on hips for the decline in female fertility remain an and buttocks in females; height increase, testos- evolutionary mystery. Abrupt female reproduc- terone production increase, upper body tive senescence is made more mysterious by strength, and deepening of vocal pitch in males. two facts: (a) that male fertility decreases Somatic investment and development continue slowly across the life span; and (b) that senes- after puberty and the end of the juvenile period, cence curves for all other bodily functions, such but both slow dramatically relative to their pre- as heart, lungs, and kidneys, show only a grad- vious rates. Both males and females develop an ual decline over the life span (Hill & Hurtado, increased desire for mating and with that comes 1991). competition for access to mates. Importantly for Maturation, senescence, and mate value. mating, juvenile humans emerge as fertile The results of these broader trends of aging and around this period and, in traditional hunter- senescence furnish specific implications for gatherer cultures, begin for the first time to be mate value. For women, age strongly predicts net calorie producers rather than net caloric fecundity and reproductive value. Figure 2 plots drains (Kaplan, Hill, Lancaster, & Hurtado, birthrate—a crude proxy of fecundity—and re- 2000). productive value as a function of women’s age. Beyond the age-graded schedule of reproduc- Fecundity refers to the probability of concep- tive maturation and entry into reproductive tion per sex act. More fecund women are more competition, age is rendered an important vari- able to produce offspring, and are thus higher able by senescence. Most organisms experience value as potential mates from an evolutionary a decline in the functioning of their bodily sys- perspective. More specifically, although impor- tems and humans are no exception. The most tant to both, fecundity should be a larger com- widely accepted theory for the evolution of this ponent of female short-term mate value rather senescence is the Medawar-Williams theory of than long-term mate value (Buss & Schmitt, senescence (Medawar, 1957; Williams, 1957). 1993). When males seek short-term mates with Even without declining bodily systems, most minimal investment, the capacity to conceive individuals would not survive to old age due to immediately is maximally important. predators, infection, starvation, accidents, or The precise age trends in female fecundity conspecific aggression. In effect, this means that are difficult to determine because fecundity is natural selection does not apply as forcefully in difficult to measure directly. Actual birth rates This document is copyrighted by the American Psychological Association or one of its allied publishers. old age as it does in youth. A gene that increases by age, or fertility, provide an indirect measure This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. the chance of death at old age—for instance, by of fecundity and for women in the U.S. peak in causing the gradual breakdown of an important the midtwenties (Martin, Hamilton, Osterman, organ system—would affect a relatively small Curtin, & Mathews, 2012), with some variation proportion of the population and therefore across time. However, fertility rates are con- would not be selected against as harshly as a founded with behavior: Fecundity can be high gene that increased the chance of death at an when fertility is low simply if people have less earlier age. As a consequence, natural selection sex or use more effective contraception methods can favor the evolution of genes that cause (see Ellison, 2003). Ovarian hormone concen- senescence as long as they counteract this cost trations provide an indirect measure of ovarian with increased reproduction early in life. functioning, which is linked to fecundity (Lip- 132 CONROY-BEAM AND BUSS

Figure 2. Women’s estimated reproductive value (Martinez, Daniels, & Chandra, 2012), women’s birthrate (Martin, Hamilton, Osterman, Curtin, & Mathews, 2012), and men’s income (U.S. Census Bureau, 2014) as a function of age. All data based on U.S. populations.

son & Ellison, 1996) and peaks in the early means that many young people, on average, thirties (Ellison, 1994). Nonetheless, hormone cannot be expected to live to reproductive age. levels are only probabilistic indicators of fecun- Reproductive value will typically peak in the dity and are most often measured cross- late teens and early twenties, after the onset of sectionally rather than longitudinally. puberty and when mortality declines (Buss, The general trend of fecundity across the life 1989; e.g., Office of Population Censuses and span is extremely clear even if the precise age Surveys [OPCS], 1996; Pawlowski & Dunbar, when fecundity peaks is less clear. Fecundity is 1999a). Reproductive value declines continu- low in prepubescence and rises to an early life ously thereafter until menopause. Theoretically, peak—approximately in the midtwenties, with the capacity to produce many children over a some cultural and individual variation (Ellison, long span is critical to males interested in long- 2003). From this peak, fecundity remains high term, committed mating. Female long-term through the late twenties or early thirties, and mate value is highest in the late teens and early then drops continuously to cessation at meno- twenties and declines gradually thereafter. This document is copyrighted by the American Psychological Association or one of its allied publishers. pause. This age-graded curve makes female Male mate value is also age-linked due to the This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. short-term mate value strongly age-linked: Fe- age-linked profile of economic resource produc- males in their mid-to-late-twenties, near their tivity (see Figure 2). Because of the substantial fecundity peak, are highest in short-term mate resource demands of pregnancy and lactation, value (Buss & Schmitt, 1993). women historically have faced the adaptive Reproductive value, on the other hand, refers problem of identifying and attracting mates who to future reproductive capacity: the average are willing and able to provide resources. number of offspring a person can be expected to Across hunter–gatherer societies, the number of produce in the future given their age. Counter- calories males produce from hunting and gath- intuitively, reproductive value is somewhat low ering rises until a peak in the midthirties (Ka- very early in life: High early life mortality plan et al., 2000). Productivity remains high AGE PREFERENCES IN MATES 133

through the forties before gradually declining benefits and few costs. The age-linked nature of until males are unable to forage. This trend mate value predicts that sexual and romantic at- remains even in modern societies, with male traction will be age-linked as well. Because fe- income rising throughout the life span to a male fecundity and reproductive value both peak slightly later peak in the late forties and early and then decline relatively early in life, males fifties (U.S. Census Bureau, 2014). Income does should be maximally attracted to younger females. drop off after this late-life peak. Further, older Conceptually, these trends are predicted to differ men have shorter expected future lifespans, and for short-term and long-term attraction. For long- therefore are less likely to provide for and sup- term mates, the age trends of reproductive value port offspring over the long-term, potentially predict that males will be maximally attracted to making very old men less valuable as long-term females nearer their peak reproductive value, mates. However, these trends are complicated in closer to their early twenties. Females below this modern societies by the fact that money can be age are predicted to be less attractive. Attraction is saved and inherited, unlike foraged foods in predicted to drop off gradually with age after the ancestral conditions. Given the importance of peak in reproductive value. Fecundity, in contrast, resources and earning potential in female long- is predicted to be the principal driver of short-term term mate preferences, the age-linked trends in mate value, so males are predicted to be maxi- resource productivity render male long-term mally sexually attracted to females in their midt- mate value age-linked. Male long-term mate wenties—that is, to women near their peak in value, to the degree that it is linked with eco- fecundity (Ellison, 1994). nomic resource productivity, is low early in life, Male attractiveness is predicted to follow a dif- and shows an age distribution corresponding to ferent age gradation, linked to resources and cues cues to decline in resource productivity. to resource acquisition as well as sperm quality. Male fecundity declines across the life span, Male long-term attractiveness should follow age but does so slowly relative to the female de- trends in resource productivity, showing a gradual cline. Nonetheless, male reproductive physiol- rise toward the peak in resource productivity and ogy introduces age as a factor to male short- a gradual drop-off thereafter. For short-term mat- term mate value. Sperm quality declines with ing, however, older males should be found less age. The sperm of older males has more dele- attractive than younger males due to the increased terious mutations that are associated with an risk of deleterious mutations. increased risk of disorders in children of older Although the age-trends of resources and re- men (e.g., Bordson & Leonardo, 1991; Kong et productive physiology are clear, several factors al., 2012). Women mating with older men there- add complexity and nuance to human mate pref- fore risk bearing unhealthy offspring that carry erence psychology. The first is that male long- higher mutation loads. This risk is costly in term attractiveness will be more culturally long-term mating contexts, it is costlier to linked than female attractiveness. Resource pro- women in short-term mating contexts, in which ductivity is affected by factors like income they might get pregnant by men with subpar equality, resource fungibility, and resource in- sperm, but from whom they will not receive heritance that vary widely across cultures, both long-term investment. We therefore offer a traditional and modern. Resource productivity novel prediction about age and mate value: in the form of hunting ability in hunter–gatherer Male short-term mate value should decline with cultures will differ from earning potential in This document is copyrighted by the American Psychological Association or one of its allied publishers. age, according to the relative risk of deleterious agrarian cultures, herding cultures, and those This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. mutations, even as long-term mate value rises with cash economies. Reproductive value and with age as a function of greater on-average fecundity, on the other hand, are considerably resource-provisioning ability. more constrained. Stated differently, there is Mate preferences for age. That mate value greater variability among males in their re- is reliably age-linked for both sexes, and undoubt- source trajectories with age than there is among edly has been throughout human history, furnishes females in their fecundity trajectories with age predictions about evolved mate preference psy- (Buss, 2016). Precisely when male attractive- chology. In order to be functional, mate prefer- ness peaks will thus depend on the specifics of ences must guide individuals toward mating with any culture’s environment as well as individu- high mate value partners—those that offer large ating qualities of different males of the same 134 CONROY-BEAM AND BUSS

age (e.g., in status and other correlates of re- selection. All males may prefer younger brides, all source potential). In contrast, female attractive- else equal, but if females prefer older husbands in ness peaks should be more invariant. return, older males and younger females should A separate constraint concerns the perception attract closer matches to their preferences than of age. The earliest formal number systems begin younger males or older females. Males, on aver- to appear approximately around 3,000 BCE. Hu- age and with greater variance, will show an in- man age preference psychology surely predates creasing ability to satisfy their preferences as they this invention and is unlikely to have changed age, up to a point, whereas females will decreas- substantially in the geologically brief period fol- ingly be able satisfy their preferences. Other as- lowing. As a result, mate preference psychology is pects of mate value will have similar effects. unlikely to be designed to take information on Higher mate value people have more power on the actual age as input relative to information on mating market and can therefore more success- perceived age. Chronological age should matter in fully attract partners they desire. For example, mate choice only indirectly, through its ability to resource possession is an important part of male affect perceived age. As a corollary, we should long-term mate value; wealthier males will be expect perceptions of age to trump information on more able to leverage their relative preference for chronological age in mate selection. youth into actually attaining youthful partners. Perceptions of age can come from the observa- These conceptually plausible constraints influ- tion of cues like facial maturity, skin quality and ence not just actual mate selection but also the smoothness, stature—social or physical—or even very mate preferences people hold. By virtue of social information. This means that females who their power on the mating market, higher mate are able to appear youthful, as many do in modern value people can afford to raise their standards and environments sheltered historically prevalent en- thus can have more stringent ideal preferences for vironmental insults, may appear younger than potential mates. Women who are kinder, more their chronological age and hence remain sexually intelligent, more physically attractive, or more or romantically attractive even as their fecundity youthful are higher in mate value and conse- and reproductive value decline. In the same way, quently can demand higher mate value men who young males can increase their attractiveness by embody their age preferences—a hypothesis that increasing their apparent maturity—physical or has been confirmed empirically (e.g., Buss & behavioral—even if their resource productivity is Shackelford, 2008). Both preferences and actual lacking, and older males also sheltered from ele- partners will be subject to market constraints, each ments that typically give the appearance of older better representing the ideal among higher mate age, may appear younger than their chronological value people. age. And of course the rise of cosmetic surgery in Finally, a key caveat centers on men’s short- modern environments allows individuals to alter term mate selection—men, but not women, dra- cues that historically would have been highly age- matically lower their minimum preferences for linked. short-term mates (Buss & Schmitt, 1993; Kenrick, Constraints on mate preferences and mate Sadalla, Groth, & Trost, 1990). Men invest very choice. Preferences are constrained in predict- little in their short-term mates: potentially as little able ways. What people desire represents ideals; as the time it takes to secure a partner and con- however, people cannot always get what they summate sex. These low costs typically make want (Buss & Schmitt, 1993; Li, Bailey, Kenrick, mating with even a low-quality short-term mate This document is copyrighted by the American Psychological Association or one of its allied publishers. & Linsenmeier, 2002). Many factors will prevent worthwhile in the currency of fitness, although This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. ideal preferences from being translated into actual there are sometimes other costs such as reputa- mate choice behavior. Actual choice behavior is a tional damage and retribution from the woman’s downstream outcome that theoretically should be mates or kin (Buss, 2015). Consequently, and influenced by ideal preferences, personal mate consistent with parental investment theory (Triv- value, influences and manipulations by other in- ers, 1972), men tend to be less selective in short- terested parties, and the realistic constraints of term mating contexts. Relative to long-term mating markets. Mutual mate choice imposes one mates, men show low minimum standards for a principle constraint. Because each person must be variety of qualities in short-term mates (Kenrick, chosen by a desired other, one’s own age will Sadalla, Groth, & Trost, 1990). Thus, while highly permit or limit translating preferences into mate fecund women should be preferred by men as AGE PREFERENCES IN MATES 135

short-term mates, men should nonetheless be will- census reports, personal ads postings, and Inter- ing to short-term mate opportunistically, when the net dating responses. This large reservoir of costs and risks are low, with women who do not available data makes hypotheses about the rela- match their ideal preferences. tion of age to mating among the most empiri- cally tractable hypotheses in all mating re- Age Is Highly Empirically Tractable search.

Humans select among potential mates based Summary on a wide array of dimensions, each of which could in principal serve as a case study in hu- The fundamental life history tradeoffs organ- man mate selection. Age is among the most isms face in allocating their time and energy to important of these dimensions in large part be- fitness-promoting goals causes organisms to fol- cause humans are acutely aware of their own low species-typical maturation schedules. For hu- ages and the ages of those around them. In fact, mans, this life historical fact causes some of the age appears to be a fundamental dimension most important features of mate value to be age along which we automatically categorize other linked in sex-differentiated ways. Female repro- humans (Brewer & Lui, 1989; Kurzban, Tooby, ductive value and fecundity both rise to early & Cosmides, 2001). In modern societies, birth- peaks and then drop off gradually across the life days mark increases in age. Moreover, age is a span, with fecundity peaking slightly later than standard item in documents both private—such reproductive value. For males, resource produc- as social networking sites, personal ads, and tivity rises steadily before hitting a stable peak in online dating—and public, such as marriage and midlife; this peak drops off relatively late in life. divorce records. The result is that everyone is While male fecundity remains relatively stable aware of their own age and able to determine or throughout life, sperm quality declines with old discover the ages of others, aside from the oc- age. As mate preferences are hypothesized to casional deception. Even in traditional societies function to guide selection of high-value mates, that lack large formal number systems, people the age-linked nature of mate value provides sev- are aware of rough relative ages. This knowl- eral predictions about the nature of mate prefer- edge manifests in behaviors ranging from mar- ences for age. In particular, women’s long-term riage decisions where people become eligible attractiveness should peak early in life and decline for marriage only at certain ages (e.g., among thereafter. Men’s long-term attractiveness will the !Kung San, girls can marry as young as 10 show a later age peak, a more gradual decline with but men are typically not eligible until their age, and greater variance. These sex difference thirties; Shostak, 1981) to status hierarchy ne- should be smaller for short-term attractiveness, gotiations (e.g., older men command more sta- with both sexes peaking earlier in life and declin- tus than younger men among the Tiwi; Hart, ing with age. However, female short-term attrac- Pilling, & Goodale, 1960). tiveness should decline more rapidly than does The widespread tracking, documenting, and male short-term attractiveness. In the following discussion of age makes age relatively unique section, we examine evidence bearing on these and particularly important among mate prefer- predictions and evidence bearing on whether these ence variables. Many other variables, such as preferences are translated into behavior, con- kindness, are also strongly preferred in mates. strained by factors like own-age and mate value. This document is copyrighted by the American Psychological Association or one of its allied publishers. Yet countries around the world presently and This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. historically record spouses’ age at marriage for Age in Mate Preferences and Mate Selection all legal marriages. These records provide large- scale, naturalistic assays of mate preference- Age is a relatively neglected variable in mate motivated behavior. We are aware of no such preference research despite the direct conceptual records that also document how kind married links between age and central components of mate spouses were to one another. Thus, in addition value and substantial evidence, from numerous to self-reports and laboratory studies available sources, that age preferences translate into real- for the study of preferences, studying age gives world behavior. Only a handful of psychological psychologists access to massive samples of be- studies explore age as a mate preference variable havioral data in the form of demographic data, directly (e.g., Buss, 1989; Buunk, Dijkstra, Ken- 136 CONROY-BEAM AND BUSS

rick, & Warntjes, 2001; Kenrick & Keefe, 1992) se, independent of their partner’s actual age. relative to the large literature on variables such as Buunk et al. (2001) challenge this alternative physical attractiveness (e.g., see Sugiyama, 2005, explanation in a survey of a Dutch community 2015, for reviews). Much evidence bearing on age sample. They found, like Buss (1989), that men predictions comes from data sources less tradi- consistently prefer long-term mates who are at tionally used by psychologists, including demo- most several years younger than themselves. graphic records, economic behavior, and historical That is, except for men in their twenties. These data. To our knowledge, no previous article has younger men were willing to accept partners attempted to broadly synthesize these diverse lit- who were up to 5 years older than themselves, eratures. with a maximal age in the mid-to-late twenties. This age preference corresponds exactly to the Male Age Preferences and Age-Related age window in which female fecundity is at Mating Behavior peak and when reproductive value is still rela- tively high. This reversal in preferences is cru- Two distinct questions can be asked about the cial evidence that male preference psychology relations between age and mating in males: (a) is attuned to the effects of age on mate value— Do men have ideal preferences for younger and not just relative partner age—because it partners? (b) Do men actually act on these ideal shows that men do not merely prefer younger preferences? We first review the evidence con- mates, but rather specifically prefer younger cerning men’s ideal preferences for partner age. mates because they are probabilistically highest We next turn to reviewing a broad array of data in reproductive value and fecundity. Even stron- sources bearing on whether men’s ideal prefer- ger evidence in favor of this conclusion comes ences affect their behavior in the mating domain from teenage boys, who are most attracted to and beyond. women who are slightly older than themselves Self-reported ideal age mate preferences. and thus near their reproductive value peaks Several mate preferences studies establish the (Kenrick, Keefe, Gabrielidis, & Cornelius, importance of youth in male mate preferences. 1996). This attraction is not reciprocated by One of the largest of these studies remains Buss teenage girls and the age preference reverses as (1989)—an examination of ideal long-term soon as men are themselves older than the age at mate preferences in more than 10,000 partici- which female reproductive value peaks. pants across 37 cultures spread across five con- Men’s age preferences are stable across cul- tinents and six islands. This study examined the tures but also across time within cultures. One ideal age difference between self and a potential study compared mate preferences within main- spouse. It found that men in all 37 cultures land China across two large samples separated preferred partners who were younger them- by a quarter of a century (Chang, Wang, Shack- selves, with the average age preference being a elford, & Buss, 2011). Men in the 1983 sample wife 2.66 years younger than oneself—an effect expressed a preference for partners younger size of d ϭ 1.94 relative to women’s preference. than themselves by 2.15 years; men in the 2008 This preference ranged from a minimum of 1.22 sample desired partners 3.41 years younger. In years younger in Canada to a maximum of 7.35 both samples, men desired much younger part- years younger in Zambia. In a more recent ners compared with women: The effect size of replication, Grøntvedt and Kennair (2013) show this sex difference was d ϭ 2.61 in 1983 and This document is copyrighted by the American Psychological Association or one of its allied publishers. in a sample from Norway, one of the most d ϭ 3.67 in 2008. Consistency over time also This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. sexually egalitarian countries in the world, that emerged in two samples of mate preferences men still prefer long-term and short-term mates from India, taken in 1984 and 2009 (Kamble, younger than themselves. And a study of 44,253 Shackelford, Pham, & Buss, 2014). Indian men online daters confirms that men prefer women in 1984 desired partners 4.50 years younger younger than they are by about 3 years (Bingol than themselves whereas Indian men in 2009 & Basar, in press). desired partners 3.92 years younger. The effect One alternative explanation for this finding is sizes for sex differences in Indian age prefer- that men prefer younger partners, not because of ences were d ϭ 4.28 and d ϭ 4.34 for the two age’s link to fecundity and reproductive value, time periods, respectively. Similar cross-time but because men desire a partner younger per stability of age preferences emerged in Brazil AGE PREFERENCES IN MATES 137

(Souza, Conroy-Beam, & Buss, 2016). In 1984, by dividing the number of ads requesting a Brazilian men preferred mates 3.22 years given age group by the number of opposite sex younger and Brazilian women 4.01 years older; advertisements offering that age group. Reflect- 30 years later, in 2014, the preferences were ing men’s preferences, women’s demand/ 2.38 and 3.59, respectively, with d values of supply ratio tracked reproductive value per- 2.30 and 1.07. fectly: women in their early twenties had the Personal mating ads by those seeking actual highest market value to men, which declined mates. Findings from these studies present evi- thereafter until approximately 40 years of age. dence that men’s ideal mates are youthful—at Age preference evidence from traditional approximately the age where reproductive value cultures. Personal advertisements provide im- peaks—but they are based entirely on self-report. portant converging evidence for a male preference Higher stakes data sources, in which actual mating for relative youth, but are limited in that adver- outcomes are sought, offer an important comple- tisements are restricted exclusively to modern so- ment to self-report data. Personal advertisements cieties. It is possible that preference trends ob- provide one such data source. served in advertisements alone may be artifacts of One study examined all personal advertise- our modern, industrial societies rather an ancient, ments published in a Brazilian newspaper over evolved preference for youth. For this reason, a 2-year period (de Sousa Campos, Otta, & de ethnographic evidence of preferences in tradi- Oliveira Siqueira, 2002). Men of all age groups tional societies is invaluable. However, these stud- expressed preferences for partners who were at ies are rare and infrequently assay preferences least several years younger than themselves— directly—instead, studies of traditional societies except, again, men in their twenties, who pre- often focus on actual marriage behavior and thus ferred mates who were at most slightly older will be covered in detail in the following section. than themselves. These Brazilian results closely Nonetheless, when Hadza hunter–gatherers of replicate those of Kenrick and Keefe (1992), Tanzania were asked to list the traits they thought who analyzed 218 personal ads from an Arizona were important in a potential mate and men, but newspaper. They found that men desired poten- not women, expressed a preference for youth tial mates who were younger than themselves (Marlowe, 2004). Furthermore, men expressed a and that this preference only strengthened with strong preference for fertility in a potential mate. men’s own age: by age 50, men were interested When asked how they could determine the fertility in partners who were 5 years their junior at the of a potential mate, the Hadza adults replied that oldest. These men preferred mates 15 years one could tell by looking at a person—presumably younger than themselves at the youngest. Once because the Hadza were using cues to age, among again, however, only for young men in their other cues, to determine the fertility and thereby twenties and early thirties was the maximum desirability of potential mates. preferred age slightly older than their own age. Short-term versus long-term age mate Nearly identical results emerged in personal ads preferences. Men’s age preferences are pre- from Germany, the Netherlands, and India dicted to differ slightly for potential short-term (Kenrick & Keefe, 1992). mates. Reproductive value is of more impor- Greenlees and McGrew (1994) found that tance to long-term mating than it is to short- men were more likely than women to state a term mating whereas immediate fecundity is desire for younger partners in a sample of 1,000 more important to short-term mating. Because This document is copyrighted by the American Psychological Association or one of its allied publishers. personal ads published in a British magazine but reproductive value peaks slightly before fecun- This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. did not report the precise age difference pre- dity, men should tend to prefer younger partners ferred. A sample of 7,415 personal advertise- for long-term mates than they do for short-term ments in a Spanish newspaper found the same: mates. Buunk et al. (2001) provides mixed sup- Men expressed preference for partners 5.7 years port for this prediction in a sample of 70 Dutch younger than themselves on average and this men. Men’s minimum preferred age for a casual desire was stronger as men aged (Gil-Burmann, affair partner corresponds strongly to the peak Pelaez, & Sanchez, 2002). of women’s fecundity, with ages ranging from Finally, Pawlowski and Dunbar (1999a) took approximately 18 to 30 as men themselves age. analysis of personal statements a step further by Contrary to predictions, the minimum age for computing “market values” of each age group marriage partners is consistently higher than the 138 CONROY-BEAM AND BUSS

minimum age for casual affair partners. How- Marriage data. An important advantage of ever, the maximum age for a potential marriage studying the relations between age and mating partner is consistently lower than that of a ca- behavior is that age is readily recorded in public sual affair partner until men themselves are in documents across cultures and across time. A key their 50s. Unfortunately, Buunk et al. (2001) do source of data bearing on whether preferences for not report data on ideal age for marriage or age manifest into actual mating behavior is there- casual affair partners—the most direct test of fore demographic data, particularly marriage doc- this prediction. uments. Across cultures, marriages are announced A much larger study of 12,656 Finns found or recorded in public documents and the age of that across men’s age, the ideal age for a sexual husbands and wives are commonly included in partner ranged from 20 up to a maximum of these reports. Moreover, the recordings of ages of approximately 35 years of age for older men brides and grooms are likely highly accurate, be- (Antfolk et al., 2015). This corresponds pre- cause they can and often are independently con- cisely to the window in which female fecundity firmed by other publicly recorded documents such is maximal but extends later than peak female as certificates of birth. If men do actually act on reproductive value. While consistent with the their desire for younger partners, these reports predicted strategy-differentiated mate prefer- should show that husbands in fact tend to be older ences, Antfolk et al. (2015) do not report data than their wives. on desired age in long-term partners. Grøntvedt Otta et al. (1999) showed that men are indeed and Kennair (2013) found that men indeed de- older than their wives in Brazil, where by legal sired short-term mates younger than them- mandate marriages had to be publicly announced selves, but did not compare ideal short- and in newspapers. They analyzed a sample of 3,000 long-term mates. Thus, the extant research pro- newspaper announcements and found that men on vides mixed support for this prediction and re- average married partners younger than them- selves—as young as 15 years younger for men quires future studies that directly compare over 50. The only exception occurred for men men’s ideal age for short-term and long-term under 20 years of age, who married slightly older partners. wives, corresponding closely to the preference In sum, there is substantial evidence that men reversal observed in young men. This age differ- prefer to mate with young women, and that ence also appears in American marriage data these preferences correspond to trends in female (Guttentag & Secord, 1983). American men marry fecundity and reproductive value. These prefer- women who are, on average, 3 years younger at ences emerge in self-report surveys across cul- their first marriage, 5 years younger at second tures as well as personal advertisements from marriage; and 8 years younger at third marriage. A Arizona to India. Marlowe (2004) shows that separate study in Albany found an age gap of 3 these trends are not merely western or modern years between husbands and their first wives artifacts but extend even to traditional societies. (Buckle, Gallup, & Rodd, 1996). Finally, there is mixed evidence that prefer- Kenrick and Keefe (1992) assembled contem- ences for age are differentiated as a function of porary marriage statistics from a single month in mating strategy, with short-term mate prefer- Seattle, WA and 2 months in Phoenix, AZ as well ences more closely tracking fecundity curves as a sample of marriages from Phoenix, AZ in than reproductive value curves. 1923. In all three samples, men married women This document is copyrighted by the American Psychological Association or one of its allied publishers. Do men act on their preferences for younger younger than themselves and this age gap in- This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. women? A crucial goal of this article is to de- creased with men’s age, just as the desired gap termine whether preferences guide actual behav- increases with age. In the contemporary samples, ior. The apparent importance of age as well as the the only age groups that married women older ease with which it can be tracked and recorded than themselves were again the teenaged men, mean there exist multiple data sources that can be corresponding to the findings for expressed pref- exploited to test the hypothesis that men’s prefer- erences of this age group. Even prior to marriage, ences are translated into actual mating behavior. men in sexually egalitarian Norway select partners These data sources include population demo- younger themselves on average and this age gap graphic data, public marriage records, crime re- grows with men’s own age (Grøntvedt and Ken- ports, and indices of courtship behavior. nair, 2013). AGE PREFERENCES IN MATES 139

What about evidence from older samples? bracket. In Baize and Schroeder’s (1995) ran- Schoen, Urton, Woodrow, and Baj (1985) ex- dom sample of 240 personal ads, response rate amined American marriage data from cohorts from men was negatively correlated with age, born between 1888 and 1980. Across cohorts, meaning that older women received fewer men’s average age at first marriage was 2.65 “hits” than younger women. Pawlowski and years older than women’s and was still 1.9 years Koziel (2002) analyzed ads from 617 Polish older in the cohorts with the smallest age gap. women; they found sex and age offered inter- Across cohorts, the magnitude of this age dif- acted to predict hit rate, with age being a strong ference was d ϭ 2.36. Extending back further in negative predictor of women’s hit rate but not time, Low (1991) analyzed marriage data from men’s. seven Swedish parishes between the years of Although personal ads now typically take the 1824 and 1840. Low does not report age differ- form of online dating profiles, the impact of age ences between spouses directly, but does find preferences remains the same. Hitsch, Hortaçsu, that men tended to marry first at a later age and Ariely (2010) analyzed the browsing be- (27.5 years of age) than women (25.0 years of havior of 22,000 users of an online dating site age). Men are older than their wives across a and attempted to predict a user’s likelihood of wide array of cultures as well. Husbands were sending an e-mail to a potential mate based on older than their wives in one sample of marriage the potential mate’s age. They found that men data from across 28 countries, ranging from preferred women either their age or 5–9 years Bangladesh, to Peru, to Yemen (Casterline, younger than themselves. Men additionally had Williams, & McDonald, 1986). The median dif- a strong bias against women older than them- ference ranged from 2.5 years in the Philippines selves. However, the authors did not find that to 9.8 years in Mauritania. older men had stronger preferences for youth. Finally, Buss (1989) collected marriage sta- Age preferences also appear to manifest in tistics from 27 countries around the world. Men mate selections at speed dating events (Kurzban married women 2.99 years younger than them & Weeden, 2005). The number of “yeses” on average, ranging from a minimum average of women receive in these events is negatively 2.17 years younger than themselves in Ireland correlated with their age. The greater desirabil- to a maximum average of 4.92 years younger in Greece. This actual age difference corresponded ity of younger women at these events is made tightly to men’s average preference for a partner more impressive by the fact that speed dating 2.66 years younger than themselves. Indeed, events suffer a crucial statistical limitation: Peo- actual age difference across countries correlated ple preferentially attend speed dating events r ϭ .68 with preferred age difference—a key attended by potential mates that fulfill their age finding that reveals a link between mate prefer- preferences (Kurzban & Weeden, 2007). Be- ences and actual mating decisions. cause men choose to attend speed dating events Dating services: Personal advertisements, attended by younger women, there is limited online dating, and speed dating. Personal variance in age within speed dating events for advertisements provide not only an index of preferences to manifest. Nonetheless, even in men’s preferences but can also be used as evi- this restricted age sample, men preferentially dence of their behavior. Many personal adver- select younger partners. tisement services not only post ads but also Economic behavior. In few domains do This document is copyrighted by the American Psychological Association or one of its allied publishers. track the responses advertisements receive. If stated mate preferences manifest into actual be- This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. men actually act on their preferences for havior more clearly than in economic conduct. younger partners, women who advertise a Exchange of resources in pursuit of desires is a younger age should receive more responses universal feature of both traditional and modern from men. de Sousa Campos et al. (2002) ana- economies; economic behavior therefore makes lyzed response rates in their sample of Brazilian an easily tracked and highly quantitative index personal ads. They found that women in the of the translation of psychological preferences 20–29 age bracket received the most responses into manifest behavior. Do men’s pattern of from men seeking mates: Nearly twice as many economic resource spending reflect their ex- as women in the 30–39 bracket and five times pressed preferences for mates in line with the as many responses as women in the 50ϩ age predictions outlined? 140 CONROY-BEAM AND BUSS

A particularly informative economic assay of baby terminology alone does not sufficiently men’s mating behavior is the money spent on reveal the age gap typical of sugar relationships, premarriage customs. Many societies have tradi- reportedly 44% of SeekingArrangement’s sugar tions that require or make strongly normative that babies were female college students in 2012 men spend large sums of money or resources in (Waldron, 2013). SeekingArrangement actively order to gain the permission to marry their desired recruits college student sugar babies through bride. In modern, Western societies this ancient free premium memberships (Seeking Arrange- custom manifests in engagement ring purchasing. ment, 2015). Men are expected to buy their brides-to-be expen- A qualitatively different form of economic sive rings—worth at least 2 months’ salary, ac- evidence comes from prostitution. Whereas pre- cording to some traditions and diamond compa- marriage rituals and sugar babying simply track nies—in order to even propose to their mates. One economic exchanges within ongoing relation- sample of 1,000 newlywed couples found that ring ships, prostitution provides a direct economic price was strongly negatively correlated with the assay of mating behavior in that money is ex- age of the future bride; men purchased more ex- changed for sexual access. Arunachalam and pensive engagement rings for younger fiancées Shah (2008) report earnings data from a sample than for older fiancées (Cronk & Dunham, 2007). of over 4,000 sex workers in Mexico and Ec- This trend is not unique to Western cultures: uador. Although not discussed by the authors, The Kipsigis, a traditional society in Kenya, their data show that the earnings of female sex have a premarriage expenditure custom known workers precisely track the age trend of fecun- as “bridewealth.” Before marriage, Kipsigi men dity: Earnings are low until they peak in the pay the families of their brides an unrecipro- early-to-midtwenties and gradually decline cated bridewealth consisting of livestock and thereafter. That this trend is linked to fertility is cash. By converting these bridewealths into further highlighted by the fact that this age- their cash value, Borgerhoff Mulder and Turke linked earning trend does not occur for female (1988) found that brides who were older at the nonsex workers, whose income peaks in the late time of their marriage commanded lower bride- 40s (Arunachalam & Shah, 2008). Similar links wealth payments than did younger brides. between age and other cues to women’s fertility An unprecedented data set bearing on this issue have been found in a study of Polish prostitutes came from a study of marriages in South Korea (Prokop, Dylewski, Wonza, & Tryjanowski, in (Sohn, 2017). A subset of these marriages occurs press). A study of U.S. female “escorts,” a com- through an unusual phenomenon—some men pur- mon euphemism for sexual services, found that chase brides from developing countries. Although younger escorts charged higher fees than older the sample of South Korean men who married escorts (Griffith, Capiola, Balotti, Hart, & Korean women (N ϭ 1,088,457) showed the usual Turner, 2016). The costs of sex are apparently age gap of several years, Korean men who pur- higher for young escorts. chase foreign brides (N ϭ 45,528) married dra- A separate sample of 248 Gambian sex work- matically younger fertile women, regardless of ers provides convergent evidence (Pickering, men’s ages, reaching two decades younger for the Todd, Dunn, Pepin, & Wilkins, 1992). Gambian older cohorts of men. In a market where men can sex workers under the age of 25 charge the most act on their preferences for young brides, they per contract, slightly above women between 25 apparently act on those preferences. and 34 and over 60% more than women above This document is copyrighted by the American Psychological Association or one of its allied publishers. Another data source comes from “sugar dad- 34. Interestingly, the number of contracts per This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. dying,” a trend wherein typically wealthy men day does not differ between the three age pay large amounts of money for the company of groups. This shows that younger women are not women often with explicit sexual arrangements. overvaluing themselves, because men are will- Popular services like SeekingArrangement.com ing to pay their higher premiums. The equiva- cater to this community by pairing “sugar ba- lence of contact number across age also reveals bies” with sugar daddies in their area. Accord- key features of male short-term mating psychol- ing to SeekingArrangement, the average sugar ogy: Men are willing to short-term mate with daddy user is 39-years-old and spends an aver- women regardless of their age, but value access age of $4,357 per month on one or more sugar to younger women enough to incur additional babies (Wade, 2013). If the sugar daddy/sugar costs. AGE PREFERENCES IN MATES 141

Finally, a recent study of 8,560 sex workers Crime data—sexual harassment and assault. from 15 different cities in Indonesia revealed an Crime statistics provide a final source of evi- age distribution of earnings that closely mim- dence. One informative domain of criminal be- icked the human fertility curve (Sohn, 2016). havior is predictors of sexual harassment in the Prices charged were highest for the age range of workplace. Given the high costs to the victims 16–24, but then dropped, hitting a low at age 40 of workplace sexual harassment, broadly de- (the oldest age in the sample considered). The fined as unwanted sexual advances, as well as highest charging sex workers were able to the potential retaliatory costs, harassment can charge fully twice as much as those at the older serve as an extreme assay of men’s mate pref- end of the distribution. In sharp contrast, the erences and their translation into behavior. Sex- wages earned by nonsex workers increased with ual harassment is disproportionately directed at age, peaking at precisely the age at which sex younger women and drops off dramatically after worker wages were lowest. 45 years of age (Studd & Gattiker, 1991). Par- Relationship maintenance, marital dissolu- ticularly informative data come from Terpstra tion, and mate retention effort. Diamonds and Cook (1985), who found that women aged and bridewealth may be forever, but the rela- 20–29 filed 46% of reported sexual harassment tionships they initiate often are not. Studying complaints despite making up only 30% of the these dissolutions, and the maintenance behav- total female workforce. Conversely, women iors that function to prevent them, can provide above 40 filed 12% of sexual harassment cases additional evidence bearing on the degree to while making up 38% of the workforce. which men’s preferences for youth are trans- An even more extreme criminal index comes lated into real-world behavior. Although we from sexual assault statistics. Regardless of should not expect dissolution and maintenance whether or not men have adaptations specifi- to be a direct function of partner mate value (see cally designed to produce sexual assault (the Conroy-Beam, Goetz, & Buss, 2015), even in- evidence is not even close to sufficient to war- direct effects should be sufficient to make men rant the conclusion that they do; see Buss, try harder to retain relationships with younger 2015), the age distribution of victims of forced partners. Betzig (1989) collected causes of mar- sex provides an informative, if unfortunate, data ital dissolution reported by ethnographers or source. Ample evidence establishes that rape informants in ethnographic reports from 186 victims are disproportionately young (e.g., see traditional societies around the world. Partner Malamuth, Huppin, & Paul, 2005 for a review). age was a moderately common cause of di- Indeed, the age distribution of victims mirrors vorce: “Old age” was listed as a cause of di- almost exactly fecundity curves for females vorce in eight separate cultures, slightly less (Thornhill & Thornhill, 1983). However, this than “bad temper” (10 cultures) and more than age distribution could occur if younger women “jealousy” (six cultures). Importantly, however, were more vulnerable to crime in general, rather across all ethnographic reports, old age of a than men specifically targeting desirable spouse was a cause of divorce only for men. younger women for sexual assault. The infrequency of old age as a cause of A better assay of whether young women are divorce may be in part because of the severity of targeted for sexual assault is the incidence of divorce; the effects of age might be clearer on opportunistic sexual assault during robberies. behaviors that are more common and less ex- These crimes naturally control for any age- This document is copyrighted by the American Psychological Association or one of its allied publishers. treme. Indeed, men married to younger partners linkages of victimization in general because the This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. were more likely to engage in more frequent comparison group remains crime victims: If mating retention behaviors like “emotional ma- younger women were merely more likely to be nipulation, commitment manipulation, posses- victimized in general, the probability of sexual sive ornamentation, intrasexual threats, and vi- assault during robberies would be constant olence against rivals” (Buss & Shackelford, across age. However, if offenders acted on ex- 1997, p. 353) in attempt to maintain their rela- pressed preferences for young women, young tionships with their partners. Men married to women should be especially at risk of sexual older partners devote less intense effort to mate assault in addition to broader victimization. The retention, even controlling for length of rela- likelihood of an offender opportunistically as- tionship. saulting a robbery victim does indeed track fe- 142 CONROY-BEAM AND BUSS

male fecundity: the risk of sexual assault during ports the prediction that women desire some- a robbery peaks in the early-to-midtwenties and what older mates. Across all 37 cultures sam- drops to near zero for victims past their 40s pled in Buss (1989)’s cross-cultural survey, (Felson & Cundiff, 2012). Thus, even in these women’s ideal long-term mate was on average extreme and abhorrent sexual assault crimes, 3.42 years older. In this study, the age prefer- men reveal a preference for youthful women. ence ranged from a low of 1.82 years older in Summary. In sum, in addition to powerful Canada to 5.1 years older in Iran. Dutch women evidence that men desire mates who are youth- similarly state a maximum age preference be- ful—younger than themselves and nearer their tween 5 and 10 years older than themselves peak in fecundity and reproductive value—a (Buunk et al., 2001). That Kenrick et al. (1996) wide array of very different data sources sug- found teenage boys prefer older mates was gest that desires translate into actual mating strong evidence that male preferences are linked behavior: (a) Men across cultures and across to fecundity and reproductive value. However, time marry women younger than themselves. the same study shows that these boys’ prefer- (b) They preferentially seek younger women as ences are not reciprocated: Women in their indicated by responding more frequently to teenage years prefer somewhat older mates and their personal mate-seeking advertisements. (c) this preference continues relatively unchanged Men spend more money on engagement rings throughout the life span (Kenrick et al., 1996). for younger women. (d) In cultures with bride- Norwegian women also express a preference for price, such as Kenya, men pay larger sums to somewhat older long-term and short-term mates acquire younger wives. (e) Men seeking prosti- (Grøntvedt and Kennair, 2013). tutes are willing to pay more money to have sex Women’s long-term age preferences show with younger than older sex workers. (f) Men just as much within-culture stability as men’s. devote more effort to mate retention when mar- In their samples of Chinese mate preferences, ried to younger compared with older wives. Sex collected 25 years apart, Chang et al. (2011) crimes provide two additional data sources. (g) found that women expressed a preference for Younger women are disproportionately victims partners 3.45 years older than themselves in of sexual harassment in the workplace. And (h) 1983 and a preference for partners 4.15 years robbers are more likely to opportunistically sex- older in 2008. Indian women showed similar ually assault younger women who happen to be age preferences (Kamble et al., 2014). In 1984, present during the robbery (see Table 1). To- Indian women expressed a preference for part- gether these eight very different data sources ners 4.19 years older than themselves; Indian provide compelling evidence that men’s age women in 2009 preferred partners 3.33 years preferences for mates actually drive men’s be- older than themselves. Brazilian women pre- havior. ferred to mate with men 4.01 years older in 1984 and 3.59 years older three decades later in Female Age Preferences and Age-Related 2014 (Souza et al., 2016). Combined, these Mating Behavior cross-time studies spanning a quarter of a cen- tury and more support a high level of consis- We have reviewed evidence that men have tency in women’s preferences for somewhat preferences for youthful women and that they older long-term mates. act on these preferences. Human mate choice, Women’s short-term preferences conform to This document is copyrighted by the American Psychological Association or one of its allied publishers. however, is usually mutual—each person must prediction as well. Because sperm quality, in the This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. select and be selected by a mate. Thus, it is form of a larger number of mutations linked important to test the hypothesis that women also with offspring abnormalities, declines with age, have theoretically expected age preferences. It the genetic benefits of short-term mating de- is also important to examine whether women’s cline as a function of increasing male age. age mate preferences translate into actual mat- Women were therefore predicted to prefer ing decisions. The evidence for these trends is slightly younger partners for short-term mating less abundant in women than in men, but it is than they do for long-term mating. Antfolk et al. sufficient to draw firm conclusions. (2015) found that women of all ages were sex- Do women prefer to mate with older men? ually interested in partners slightly older than Data on stated mate preferences strongly sup- themselves, approximately 7 years older at age AGE PREFERENCES IN MATES 143

Table 1 Summary of Evidence That Men Act on Age Preferences

Evidence domain Method Finding Citations Mate Questionnaire Men across cultures report a desire Buss, 1989; Buunk, Dijkstra, Kenrick, & preferences for younger long-term partners. Warntjes, 2001; Kenrick, Keefe, Gabrielidis, & Cornelius, 1996; Grøntvedt & Kennair, 2013 Men prefer younger long-term Chang, Wang, Shackelford, & Buss, partners across generations 2011; Kamble, Shackelford, Pham, & within cultures. Buss, 2014 Teenage men prefer long-term Buunk et al., 2001; Kenrick, Keefe, partners slightly older than Gabrielidis, & Cornelius, 1996 themselves. Men prefer younger short-term Mixed: Buunk et al., 2001; Antfolk et mates than long-term mates. al., 2015 Dating Men advertise a desire for younger de Sousa Campos, Otta, & de Oliveira services long-term partners. Siqueira, 2002; Kenrick & Keefe, 1992; Greenlees & McGrew, 1994; Gil-Burmann, Peláez, & Sanchez, 2002; Pawlowski & Dunbar, 1999a; Phua, Sosa, & Aloisi, 2017). Teenage males advertise a desire de Sousa Campos, Otta, & di Oliveira for slightly older partners. Siqueira, 2002; Kenrick & Keefe, 1992 Traditional Men, but not women express a Marlowe, 2004 cultures preference for youth in potential mates. Mating Marriage data Men’s long-term and marriage Otta, da Silva Queiroz, de Sousa behavior partners are younger than Campos, Weronika Dowbor da Silva, themselves. & Silveira, 1999; Guttentag & Secord, 1983; Buckle, Gallup, & Rodd, 1996; Kenrick & Keefe, 1992; Grøntvedt & Kennair, 2013 Men have married younger Schoen, Urton, Woodrow, & Baj, 1985; partners across time. Low, 1991 Men marry younger partners Casterline, Williams, & McDonald, across cultures. 1986; Buss, 1989 Dating Younger women receive more de Sousa Campos, Otta, & di Oliveira services responses from men. Siqueira, 2002; Baize & Schroeder, 1995; Pawlowski & Koziel, 2002 Men preferentially contact younger Hitsch, Hortaçsu, & Ariely, 2010 women on online dating sites Men preferentially attend speed Kurzban & Weeden, 2005; Kurzban & dating events with younger Weeden, 2007 women. Men additionally select younger partners within these events. Economic Men spend more resources on pre- Cronk & Dunham, 2007; Borgerhoff This document is copyrighted by the American Psychological Association or one of its allied publishers. behavior engagement traditions (e.g. Mulder & Turke, 1988 This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. engagement rings, bridewealths) for younger wives. Men pay more for sex with Arunachalam & Shah, 2008; Pickering, younger prostitutes. Todd, Dunn, Pepin, & Wilkins, 1992; Griffith, Capiola, Balotti, Hart, & Turner, 2016 Men pay for relationships with Wade, 2013; Waldron, 2013 predominantly younger “sugar babies.” (table continues) 144 CONROY-BEAM AND BUSS

Table 1 (continued) Evidence domain Method Finding Citations Relationship Men, but not women, list “old Betzig, 1989 maintenance age” as a cause of divorce across traditional cultures. Men engage in more mate Buss & Shackelford, 1997 retention behaviors for younger partners. Crime data Men are more likely to sexually Studd & Gattiker, 1991; Terpstra & harass younger women. Cook, 1985 Younger women are more often Malamuth, Huppin, & Paul, 2005; sexually assaulted, even Felson & Cundiff, 2012 controlling for victimization in general.

20, but that the desired age gap declined as (Pawlowski, 2000). This is the reverse of men’s women approached 40. Buunk et al. (2001) preferences in the same sample: Men prefer provides even clearer evidence in favor of this younger partners at all ages, with the gap pre- prediction: With the exception of the maximum ferred growing wider as men age. Finally, Paw- desires of females in their twenties, in both lowski and Dunbar (1999a)’s market value in- minimum and maximum age desired, women dex, derived by dividing the proportion of preferred their casual affair and sexual fantasy advertisements asking for mates of a given age partners be younger than their marriage part- by the number of advertisements offering that ners, as predicted. age, showed that men in their late thirties were Studies of personal advertisements for mates of the highest market value. In sum, across provides strong convergent evidence that cultures, methods, time periods, and age, women prefer to mate with somewhat older women express a clear preference for long-term men. Women who commission Brazilian per- partners older than themselves and near their sonal ads request partners at a minimum their peaks in resource productivity. age or slightly older and at most more than 10 Do women act on their preferences for some- years older than themselves (de Sousa Campos what older men? Several sources of evidence et al., 2002). Kenrick and Keefe (1992) found can be used to examine this question. that women were willing to accept a partner Marriage data. In addition to showing that slightly younger than themselves at the young- men tend to marry partners younger than them- est, but across all age groups preferred a partner selves, Otta et al. (1999) found that women 10 years older than themselves at the oldest. tended to marry husbands slightly older than Precisely the same trend was found in German themselves. This trend started with a 5-year age and Dutch personal advertisements. This trend gap for women below 20, but gradually dwin- was even more extreme in Indian advertise- dled to an age gap of zero when women were ments, where the youngest acceptable age dif- above 50. By necessity, that American hus- ference was zero across the life span. In contrast bands are 3 years older than their wives also This document is copyrighted by the American Psychological Association or one of its allied publishers. to men, who more often seek younger partners, indicates that wives are succeeding in acquiring This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. Greenlees and McGrew (1994) found that the older men they desire (Guttentag & Secord, women were more likely to ask for older part- 1983). This same rationale applies to 20th cen- ners. Spanish women of all age groups express tury American marriages (Schoen et al., 1985) in their personal advertisements a preference for and 19th century Swedish marriages (Low, older men with an average preferred age differ- 1991): Women are on average approximately 2 ence of 4 years (Gil-Burmann et al., 2002). In to 3 years younger than their husbands at their Polish personal advertisements, women of all first marriage. Grøntvedt and Kennair (2013) ages express a preference for partners older than found that women’s long-term partners, who themselves—though the magnitude of the age may or may not be married, were indeed older difference shrinks as women themselves age than the women themselves for all age groups. AGE PREFERENCES IN MATES 145

Figure 3. Average age at marriage in Norway from 1851–2002 from Norwegian census data (Statistics Norway, 2015). Men are consistently older than their partners across all time periods. Note that data from before 1991 is binned into groups of five years and that the age axis begins at 20 years of age.

This accords with Norwegian census data (see with husbands older than wives. The 2.99 year Figure 3). From 1851 to 2002, Norwegian mar- average age difference between spouses found riage data shows a consistent age gap between in Buss (1989) corresponds well to women’s spouses whereby women marry men 2.74 years preference that their partners be 3.42 years older their senior on average (Statistics Norway, than themselves. In fact, the average difference 2015). This gap between spouses persists across preferred by men and women was the wife 3.04 time despite changes in marriage age overall as years younger than her husband, suggesting ac- well as quite radical social and political changes tual marriage age may represent a compromise within Norway over this period. These include between men and women’s desires. two world wars, an energy-driven economic Spousal age differences conform to predic- boom, and women’s suffrage as part of a period tions across time within cultures as well. In of increasing political progressiveness and gen- 1982, women in China were 2.8 years younger der egalitarianism. than their husbands; Chinese husbands were This document is copyrighted by the American Psychological Association or one of its allied publishers. Kenrick and Keefe’s (1992) marriage statis- still 2.15 years older than wives in 2008 (Chang This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. tics showed, for both the 1923 sample and the et al., 2011). Indian women in 1982 were 4.70 two more contemporary samples, that women years younger on average than their husbands; on average married men older than themselves. in 2011, this age difference was 3.80 years As with their stated preferences, at no age did (Kamble et al., 2014). women on average marry partners younger than Sex differences in marriage age are present themselves. Women in New York marry men across cultures, but variability in marriage age 2.7 years older than themselves on average across cultures reveals important features of age (Buckle et al., 1996). Across the 28 countries preference psychology. Recall that the trend in sampled in Casterline et al. (1986), the median men’s mate value across age is expected to vary age difference between spouses was 5.44 years, across cultures more than the same trend for 146 CONROY-BEAM AND BUSS

women. This is because the desirability of Sousa Campos et al. (2002) do not report the men’s age is linked to age trends in resources age of responders, but do report that over 75% productivity, which can vary widely across cul- of female advertisers fell between the ages of 30 tures; the desirability of women’s age is linked to 49—younger than the 50ϩ year old men who to more cross-culturally stable age trends in received the most responses and older than the fecundity and reproductive value. Consistent relatively ignored men in their thirties. Two with this prediction, variability in husband mar- separate studies provide convergent findings. riage age across cultures dwarfs variability in Age was positively correlated with the response wife marriage age: Across countries, the aver- rate to men’s personal advertisement in one age variance in husband’s age at marriage is sample of personal advertisements (Baize & 47.54 whereas the average variance in wife’s Schroeder, 1995). In a sample of Polish per- age is just 16.13 (Casterline et al., 1986). More- sonal ads, age was the second strongest predic- over, age differences within cultures are over- tor of the response rate experienced by men whelmingly determined by variability in hus- (Pawlowski & Koziel’s, 2002). Education was band’s age. This shows that men consistently the only stronger predictor—another indicator prefer to marry younger women, nearer their of resource earning potential. peak in reproductive value, across cultures. Women using online dating services also act However, women’s age preference psychology in accordance with consensual preferences appears to be more sensitive to cultural context. (Hitsch et al., 2010). Women’s initial contact Unfortunately, Casterline, Williams, and Mc- behaviors show a preference for men who are Donald (1986) did not compare men’s marriage their age or slightly older. Women also show age with the age at which men’s income peaks. some aversion to younger men. Finally, in speed This leaves open a potential alternative expla- dating, women are curiously less likely to “yes” nation for these findings: Cultures with larger to older potential mates (Kurzban & Weeden, age gaps may be cultures in which people sim- 2005). However, this apparent reversal is com- ply marry later. We know that the age gap plicated by the fact that women preferentially preferred by men increases as men themselves attend speed dating events attended by older age (e.g., Kenrick & Keefe, 1992). Cultures in men (Kurzban & Weeden, 2007). In speed dat- which people marry later on average may sim- ing, women thus appear to seek out pools of ply show a larger age gap between spouses older potential mates, but select younger part- because older men are acting on their more ners within those pools of older men. extreme mate preferences, and not necessarily Summary. In sum, data concerning wom- because male income peaks later in these cul- en’s mate preferences and their translation into tures. A critical test that could distinguish these behavior are less available for, and overlap alternative hypotheses thus remains for future heavily with, data available for men. Nonethe- research: If variability in men’s marriage age is less, the available data strongly support the driven by cross-cultural variability in men’s in- same conclusion: women have preferences for come trajectory, cross-cultural variation in hus- age in potential mates and they act on them. band age should be predictable by cultural vari- Table 2 reviews these data sources. Women ation in age at peak income. across cultures self-report a desire for long-term Dating services. Women as well as men partners older than themselves and in no cul- behaviorally reveal their mate preferences ture, modern or traditional, do women express a This document is copyrighted by the American Psychological Association or one of its allied publishers. through their responses to personal advertise- desire for youthful long-term partners. Age This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. ments. While the response rate experienced by preferences are common even in nontraditional women declines dramatically with age in Bra- mating markets, like mail-order marriages. zilian personal advertisements, the response rate These preferences emerge in women’s personal experienced by men begins low in the 20–29 advertisements across cultures where women bracket and increases dramatically, ultimately both request older partners and preferentially peaking for men older than 50 (de Sousa Cam- respond to ads of older men. Finally, women’s pos et al., 2002). In fact, the personal ads of men preferences for age manifest in marriage records over 50 receive over four times as many re- across generations, wherein women consistently sponses as ads from women of the same age and marry partners older than themselves. These as ads from men below 30. Unfortunately, de multiple streams of evidence converge on one AGE PREFERENCES IN MATES 147

Table 2 Summary of Evidence That Women Act on Age Preferences

Evidence domain Method Finding Citation Mate Questionnaire Women report a desire for somewhat Buss, 1989; Buunk et al., 2001; Kenrick, preferences older long-term partners. Keefe, Gabrielidis, & Cornelius, 1996; Grøntvedt & Kennair, 2013 Women prefer somewhat older long- Chang et al., 2011; Kamble et al., 2014 term partners across generations within cultures. Women prefer younger short-term Mixed: Buunk et al., 2001; Antfolk et mates than long-term mates. al., 2015 Personal Women advertise a desire for de Sousa Campos, Otta, & di Oliveira advertisements somewhat older long-term Siqueira, 2002; Kenrick & Keefe, partners. 1992; Greenlees & McGrew, 1994; Gil-Burmann, Palaez, & Sanchez, 2002; Pawlowski & Dunbar, 1999a Mating Marriage data Women’s long-term and marriage Otta et al., 1999; Guttentag & Secord, behavior partners are somewhat older than 1983; Grøntvedt & Kennair, 2013; themselves. Buckle, Gallup, & Rodd, 1996 Women have married somewhat Schoen et al., 1985; Low, 1991; older partners across time. Statistics Norway, 2015; Kenrick & Keefe, 1992 Women marry older partners across Casterline et al., 1986; Buss, 1989 cultures. Dating services Older male advertisers receive more de Sousa Campos, Otta, & di Oliveira responses from women. Siqueira, 2002; Baize & Schroeder, 1995; Pawlowski & Koziel, 2002 Women using online dating sites Hitsch et al., 2010 prefer same-age or slightly older men Women preferentially attend speed Kurzban & Weeden, 2007 dating events with older potential mates

strong conclusion: Mate preferences for age their preferences in actual mate selection. For drive human mating behavior. instance, if adolescent males are less desirable to the targets of their desires—highly fertile Competition for Mates: Who Is Able to women a few years older than they are—these Implement Age Preferences in Actual men will encounter tremendous difficulty at- Mating Outcomes? tracting those partners. Thus, if mate prefer- ences for age do manifest in actual mating be- The findings discussed so far have concerned havior, in addition to the on-average tendency one process of sexual selection: intersexual se- lection, or preferential mate choice. Successful for people to pursue and wed partners who This document is copyrighted by the American Psychological Association or one of its allied publishers. mating also requires another hurtle—competing match their preferences, we should be able to This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. with those who share similar desires. A key observe principled individual differences. Men component of this causal process involves em- and women high in mate value should be more bodying, or seeming to embody, the desires of successful in translating their age preferences potential mates more completely than competi- into age selections. tors. Mate competition imposes a key constraint Remarriage. Remarriage data provides an on a direct or one-to-one translation of desires excellent source of evidence for testing the hy- into actual mating outcomes. Some individuals pothesis that competitiveness on the mating lack the qualities necessary to be competitive on market, particularly in terms of mate value, acts the mating market; those low in mate value as a critical moderator of the ability to translate encounter formidable difficulties in fulfilling mate preference into mate selection outcomes. 148 CONROY-BEAM AND BUSS

Partners who divorce are necessarily older at the widowed and divorced men remarry at a higher time of their divorce than they were at their rate than women, ranging from an approximate marriage. Consider a woman, age 26 who mar- low of 12% relative probability for divorced men ries a man age 28—the current average age of in New Zealand to a high of 889% in Egypt. first marriage in the U.S.—who are perfectly Where data are available, these sex differ- matched on mate value at the time of marriage, ences are amplified with age despite an overall but who divorce a decade later. Considering just decline in remarriage rate with age. For in- the average age curves for fecundity and re- stance, for 25- to 29 year-old widows and wid- sources, the now 36-year-old woman will have owers in Egypt, men remarry more than women dropped in mate value while the now 38-year- by a factor of 2.72; for widows and widowers old man will have increased in mate value. This between ages 50–54, men remarry at a higher makes divorced men higher in mate value, on rate by a factor of 49.5. Even in the group with average, when they reenter the marriage market, the smallest change across age, divorced and divorced women lower in mate value. If Swedes, men’s remarrying rate changes from men and women act on their preferences for being greater by a factor of 1.03 between ages age, this dynamic should make ex-husbands 25–29 to being greater by a factor of 1.67 be- fare better on the mating market than their ex- tween ages 50–54. The CDC’s Monthly Vital wives: Men should have an easier time remar- Statistics Report (1995) corroborates this sex rying than do women and should more success- difference in U.S. remarriage rates from 1980 fully attract partners who better match their age and 1990, the last years for which statistics are preferences. available. As Figure 4 shows, men and women Kuzel and Krishnan (1973) analyzed census start with relatively similar remarriage rate early data on Canadian remarriages from 1961–1966. in life, but men’s remarriage relative to wom- They found that whether divorced or widowed, en’s climbs with age as men increasingly re- men of all ages were more likely to remarry by marry more than do women. age 80 than were women. For widowed remar- Remarriage probabilities clearly indicate that riers, the gap in remarriage probability widened divorced or widowed men are more likely to particularly around age 40, as fecundity and remarry than their female counterparts—a trend reproductive value begin to decline for women that becomes increasingly pronounced with in- faster than men: Widowed men in their thirties creasing age. This trend is precisely predicted have a .98 probability of remarrying relative to because men’s now-increased age increases women’s probability of .71. This relative prob- their mate value whereas women’s increased ability, whereby men are 38% more likely to age decreases their mate value. However, other remarry than women, spikes to a relative prob- factors could drive this sex difference in remar- ability of 97% as men and women enter their riage as well: For instance, women may have a 40s. Men were not only more likely to remarry more difficult time remarrying if they are more than women, but also remarried faster. Men often the primary caregivers after divorce. The remarried 7.66 years faster across age groups presence of stepchildren is a strong predictor of for divorced people and 8.21 years faster for marital and family conflict (Daly & Wilson, widowed people. 1996) and likely makes the initiation of new American data from across the 20th century marriages more challenging. Additionally, the shows similar trends (Schoen et al., 1985). Across same trends could occur if men were merely This document is copyrighted by the American Psychological Association or one of its allied publishers. all cohorts in this study, divorced men were on relaxing their standards for remarriage. Within- This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. average 7% more likely to ever remarry than sex remarriage comparisons are therefore a cru- divorced women. Particularly striking, widowed cial supplementary data source: Men should be men were 167% more likely to remarry than win- more likely to remarry than women and remar- dowed women, although this effect is undoubtedly rying men should acquire partners who fulfill partly due to the sex ratio imbalance among much their preferences more than do their younger older samples. This trend occurs across cultures as competitors. Women, on the other hand, should well (Chamie & Nsuly, 1981). Although remar- have more difficulty fulfilling their mate pref- riage behavior varies across cultures in response to erences: those women who do remarry should many factors—laws, religion, tradition—in each tend to acquire partners further from their pref- of 47 cultures, from every inhabited continent, erences than do younger women. AGE PREFERENCES IN MATES 149

Figure 4. Sex difference in remarriage rate (men’s rate/women’s rate) as a function of age. Based on U.S. demographic data for 1989 and 1990. Men become increasingly more likely to remarry than women with increasing age.

Consistent with these predictions, for Amer- with increasing age. Men are more likely to re- ican men the average age gap within first mar- marry than women after divorce or widowing and riage is just 3 years; this gap increases to 5 years this difference persists across countries and across within second marriages and 8 years within time. Men are also more likely than their exwives third marriages (Guttentag & Secord, 1983). A to acquire partners who better match their mate separate study found that men averaged remar- preferences both absolutely and relative to their riage partners 6 years younger than themselves first partners. These sex differences occur because whereas their first wives were just 1.5 years remarrying men are able to leverage their in- younger on average (Buckle et al., 1996). If creased age, presumably tracking their on-average older men are marrying increasingly younger increased resource holding potential, into higher women as they divorce and remarry, this im- mate value and better mate choices. Women’s plies that older women are not securing the men increased age lowers their overall mate value as a they desire. Interestingly, the same study found function of decreased fecundity and reproductive that women did not change their age gap upon value, forcing them to compromise. Coupled with remarriage and were therefore acquiring part- findings indicating that men and women each pre- ners of slightly higher mate value than their first fer and pursue partners younger and older than partners, though not to the same extent as were themselves, respectively, remarriage data provides their exhusbands (Buckle et al., 1996). Fieder evidence that age preferences are robustly mani- and Huber (2007) analyzed marriage data from fested in mating behavior—a translation of pref- over 10,000 Swedish men and women and erences into actual matings that is moderated by found that men’s first partners were 1.74 years mate value. their junior relative to an age gap of 6.10 years for Mate value. Personal age affects the extent This document is copyrighted by the American Psychological Association or one of its allied publishers. second partners. Women’s age gap, in contrast, to which men and women are able to satisfy This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. decreased, with women selecting mates 3.18 years their preferences for age because age is an im- their senior for first partners but settling for an age portant component of mate value. But age, of gap of just 0.90 years for second partners. This course, is not the only component of mate value. trend is not novel: 19th century Swedish men If high mate value people are better able to married women 0.45 years older than themselves translate their preferences for age into actual for a first marriage but then acquired partners 10.6 mate selections, determinants of mate value in years younger than themselves for second mar- general should predict partner age alongside riages (Low, 1991). personal age. Status and resources are relatively Men, on average, fare better on the remarriage important components of male mate value market than do women—a trend that increases (Buss, 1989; Kenrick et al., 1990; Symons, 150 CONROY-BEAM AND BUSS

1979), so men possessing these qualities should embody the age preferences of the opposite sex be more able than men lacking these qualities to have more bargaining power on the mating mar- implement their mate preferences in actual mat- ket and therefore are able to get away with ing outcomes. Among 19th century Swedish setting higher standards. Theory therefore pre- men, age of wife was a near direct function of dicts that these individuals—younger women the man’s resources, with the youngest wives on and older men—would have more stringent average (24.5 years) going to upper-class men mate preferences in general. Munro, Flood, who had the most land or largest businesses and McKellar, and Reudink (2014) analyzed prefer- progressively older wives going to men of lower ences sought as a function of age in a sample of classes: 25.0 years, 25.7 years, 26.9 years, and 1,275 female personal advertisements from cit- 25.5 years, respectively, for descending re- ies across Canada. They found that younger source classes (Low, 1991). women placed more emphasis on the resources These mate value effects can be so strong that of potential mates in their ads. In a separate traditional societies like the Tiwi of Australia study, women of the highest market value, those can at first appear to flout the broader trends of closest to peak fecundity and reproductive age preferences. Among the Tiwi, young men value, demand the largest number of traits in marry the oldest women, in contrast to their their personal advertisements (Pawlowski & predicted preference for youthful brides. How- Dunbar, 1999a). High market value men also ever, this occurs only because the older, highest demanded more traits in their advertisements status men marry the youngest women before with the exception of a single outlier. younger men get the chance. For Tiwi men Deception about age in the mating market. under 30, marrying older women is a political If age is an important factor in actual mate strategy: By marrying these women, young men selection, we should expect to observe some get the political clout and connections they need degree of deception about age in mate compe- for the opportunity to marry younger women tition. Those able to obscure true age would later in life (Hart, Pilling, & Goodale, 1960; have been able to deceive their way into better Kenrick, Nieuweboer, & Buunk, 2010). mateships, either by concealing an undesirable Another interesting source of evidence comes age or by faking a more desirable age. Make-up from studies of kings and other men of excep- products like concealer, explicitly designed and tionally high status or power. Theoretically, we advertised to mask age, hint at the existence of expect these men to be in the best position to age-deceptive adaptations. Personal advertise- translate their mate preferences into actual mate ment data provides some empirical support. selections. In the 1700s and 1800s, wealthier Women are more likely than men to withhold men from the Kummerhorn population of Ger- their age in their personal ads (Greenlees & many married younger brides than did men McGrew, 1994). Given that the average age of lacking wealth (Voland & Engel, 1990). Histor- the advertisers who did report an age was 35, ical studies of kings and despots found that they approximately the age at which women’s age- routinely stocked their harems with young, at- linked mate value begins to decline, this implies tractive, nubile women (Betzig, 1992). The Mo- that women are masking their true age to avoid roccan emperor Moulay Ismail, for example, the accompanying decline in response rates. reportedly sired some 888 children with roughly Pawlowski and Dunbar (1999b) found that 500 women. When a woman in his harem women, but not men, who did not state their age This document is copyrighted by the American Psychological Association or one of its allied publishers. reached the age of 30, she was moved out of the in their personal advertisements were more de- This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. emperor’s harem and into a lower-level leader’s manding in their mate preferences. They also harem, and then replaced with a younger wom- used linear regression of age sought as a func- an. Roman, Babylonian, Egyptian, Incan, In- tion of stated age to estimate the age of the dian, and Chinese emperors all apparently withholding women. This regression yielded a shared the preferences of Emperor Ismail and predicted age of 41 years old, the age at which enjoined their trustees to scour their lands for as women’s response rates are declining. Women many pretty young woman as could be found omitting age information therefore seem to be (Betzig, 1992). concealing their older age in attempt to attract A subtler prediction concerns the relationship partners, or to widen the potential pool of po- between age and mate preferences. People who tential mates who might otherwise not respond. AGE PREFERENCES IN MATES 151

Summary. Separately from the mate pref- tral to human reproduction over human evolution- erences and mate selection behavior of each ary history, and hence central to evolved mating sex, convergent evidence across very different psychology. data sources all point to the conclusion that The first—reproductive capacity—accrues its men’s and women’s mate competition in actual theoretical importance from the straightforward mating markets is directly affected by age (see fact that all living humans are descendants of a Table 3). Men are more successful on the mar- long and literally unbroken line of ancestors, riage market as they age, on average, and are each of whom chose mates with qualities cor- more likely to acquire partners that satisfy their related with reproductive capacity. If our ances- mate preferences; women remarry less as they tors failed to do so, they would have failed to age and increasingly settle for partners younger reproduce and failed to leave descendants. Con- than their ideal. Higher mate value men, as sequently, in addition to managing to survive to indicated by status and resources, are better able reproductive age, choosing a mate capable of translate their preferences for youthful women reproduction historically has been possibly the into mate selection behavior. Younger women, most important decision an individual could on the other hand, demand higher mate value make. As descendants of this unbroken chain of partners. Moreover, older women are more ancestors, modern humans carry with them the likely than younger women to conceal their age. mating psychology that led to their ancestor’s Mate preferences for age, in short, appear to reproductive success. Because age is the most drive not only men’s and women’s mate choice important available predictor of reproductive behavior, but also drive tactics of mate compe- capacity for women, it follows that age and cues tition, mate attraction, and deception of the op- to age should figure prominently in men’s mate posite sex. preference psychology. Age is also a key predictor of men’s status Conclusions and resources, albeit a predictor with greater variance than the corresponding age-reproduc- Cogent theoretical rationales and abundant em- tive capacity link for women. In no culture do pirical evidence converge on the conclusion that adolescent men experience, on average, the age is an exceptionally important variable in hu- highest status or secure the most resources. man mating. Age lies at the heart of two sets of Studies of the links between age and hunting variables crucial to mate value—fecundity and abilities in hunter-gatherer societies and be- reproductive value in women, and status and re- tween age and resource-acquisition in more source earning potential in men. There are pow- modern societies, all point to the conclusion that erful theoretical reasons for predicting that both age is a strong correlate of male resource acqui- age-linked variables will be, and have been, cen- sition. An important conceptual caveat is that

Table 3 Summary of Evidence of Intrasexual Competition Over Age Preferences

Evidence domain Finding Citation

This document is copyrighted by the American Psychological Association or one of its allied publishers. Remarriage Men are more likely to remarry than women. Kuzel & Krishnan, 1973; Schoen et al., 1985; Chamie &

This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. Nsuly, 1981 The sex difference in remarriage rates Kuzel & Krishnan, 1973; Chamie & Nsuly, 1981; CDC increases with age. Monthly Vital Statistics Report, 1995 Men, but not women, increasingly satisfy Guttentag & Secord, 1983; Buckle, Gallup, & Rodd, their age preferences with remarriage. 1996; Fieder & Huber, 2007; Low, 1991 Mate value High status men marry younger mates than Low, 1991; Hart, Pilling, & Goodale, 1960; Kenrick, low-status men. Nieuweboer, & Buunk, 2010; Voland & Engel, 1990; Betzig, 1989 Younger women and older men have more Munro, Flood, McKellar, & Reudink, 2014; Pawlowski demanding mate preferences. & Dunbar, 1999a Older women are more likely to conceal Greenlees & McGrew, 1994; Pawlowski & Dunbar, their age. 1999b 152 CONROY-BEAM AND BUSS

with increasing age, men experience consider- they closely track reproductive capacity in fe- able variance in resource acquisition. Unlike males. Also based on the voluminous literature female reproductive capacity, which shows a reviewed, age preferences in a mate expressed tighter linkage with age, age is a good but by women, to a clear but somewhat lesser de- nonetheless weaker predictor of male resource gree, confirm the prediction that they track this acquisition. This leads to the more refined pre- key correlate of status and resources. dictions that among same-age men, those who have access to more abundant resources should Do Sex Differences in Age Preferences be better able to fulfill their desires for younger Show Large and Replicable Effect Sizes? women—a specific prediction supported by em- pirical evidence spanning cultures and centu- Yes. The sex differences in age preferences ries. Over evolutionary history, women who are among the largest and most robust findings chose mates who were both able and willing to in cross-cultural studies of mate preferences. channel resources to themselves and their off- While the typical effect size in psychology hov- spring would have out-reproduced women to ers around a d of 0.20–0.30 (Funder & Ozer, were indifferent to these key qualities. 1983), sex differences in age mate preferences In addition to these clear conceptual expec- are often in the neighborhood of d ϭ 2.00, tations, age is also one of the most empirically dramatically greater than typical psychological tractable dimensions of mate choice. It is uni- effects. This effect size, secured through multi- versally tracked and recorded, often in public ple methods, large samples, and multiple cul- documentation, which itself reveals its impor- tures, places sex differences in age mate pref- tance in human affairs. Being a single and ob- erences as among the largest psychological sex jective numerical value, the recording and mea- differences ever demonstrated in the history of surement of age is exceptionally reliable. psychology. And in an era in which many psy- Because mate preferences for age and its corre- chological findings have proven unreplicable, lates could not have evolved if they did not what some call a replication crisis in psychol- influence actual mating behavior, it is critical to ogy, these age mate preferences are among the determine whether, and under which conditions, most replicable psychological findings ever these mate preferences govern a suite of mating- documented. related outcomes. These include perceptions of attractiveness, actual short-term mate seeking, Do Age Mate Preferences Influence Actual differential responsiveness to mating opportuni- Mating Behavior? ties, choices of marriage partners, and patterns of remarriage following divorce. They should Yes. Mate preferences could not evolve un- also include tests of the hypothesis that those less they influenced actual mating behavior, high in mate value are most able to translate from mates sought, mates courted, mates se- their mate preferences into actual mating out- lected, mates retained, and even mates divorced. comes. Finally, they should include important For cogent conceptual reasons, mate prefer- classes of mating behavior derived from the ences cannot be translated invariantly into ac- second major component of sexual selection, tual mating behavior. Most centrally, a person’s patterns of mate competition. Exploring these mate value limits the pool of potentially acces- large and numerous bodies of findings answers sible mates. And unlike food selection, mate This document is copyrighted by the American Psychological Association or one of its allied publishers. several key questions about age and its relation- selection typically requires reciprocity—a cho- This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. ship to human mating. sen mate must choose in return. Given these clearly specified constraints of mating market Does Age Manifest in Human dynamics, the findings from marriage data, re- Expressed Preferences? marriage data, personal ad response rates, finan- cial decisions, relationship maintenance, prefer- Yes. Based on the empirical literature re- ence standards, mail-order bride preferences, viewed in this article, using multiple studies, deception, sexual harassment, and sexual as- multiple methods, multiple cultures, and multi- sault rates support a singular conclusion: When ple time periods, expressed age preferences in a it comes to age, mate preferences exert a pow- mate by men confirm the central hypothesis— erful influence on actual mating behavior. AGE PREFERENCES IN MATES 153

Broader Implications of Age in Human Mating whom we spend our lives and raise our children. Competition for and pursuit of mates guides These conclusions have important implica- how we spend our money, funding billion- tions for several disciplines, ranging from evo- dollar industries in areas like dating services lutionary biology to psychology to economics. and cosmetics. Disturbingly, our mating ideals Implications for sexual selection theory applied even appear capable of compelling some to to humans. Consider first the implications for commit life-altering crimes that impair wom- evolutionary biology. Sexual selection theory, en’s safety and well-being. The choice of a mate composed of the component processes of pref- is one of the most critical decisions a sexually erential mate selection and intrasexual compe- reproducing organism can make. Mate prefer- tition, has long been the central theoretical ences are consequently much more than idle framework for understanding mating in sexu- fantasies; preferences are potent motivations ally reproducing species (Andersson, 1994). that shape our world. Evolved mate preferences that influence actual In sum, the findings reviewed here weigh mating behavior have been documented in thou- heavily on theories of human mating and fur- sands of sexually reproducing species, from nish researchers several important opportunities common fruit flies to Mormon crickets to mam- and insights. The role of age in human mating, mals and primates (e.g., Alcock, 2013; Arnqvist & Rowe, 2005; Thornhill & Alcock, 1983). The in short, has profound implications for multiple current article documents decisively that sexual disciplines—placing humans within the biolog- selection theory provides a fundamental frame- ical context of other sexually reproducing spe- work for understanding human mating psychol- cies; shedding light on important debates within ogy (Buss, 1995). This conclusion contravenes the field of psychology; and revealing the many views that humans have somehow been exempt ways in which mating influences human behav- from the processes of sexual selection. It places ior across domains. Our review of the literature our species squarely within the broader context on age preferences provides a cogent conceptual of all sexually reproducing species. framework for further understanding the im- Implications for debates about whether mate pacts of age preferences on human mating be- preferences influence actual mating behavior. havior and a solid, extensive body of supporting The current conclusions also have important im- empirical findings, hallmark characteristics of plications for several debates within psychology. mature and growing science. Finally, and cru- One debate concerns whether mate preferences cially, in providing a window into mate prefer- influence actual mating behavior, or whether they ences more broadly, the body of work surround- are inconsequential beyond people’s beliefs of ing age preferences firmly supports one what they desire. The current findings strongly conclusion: Mate preferences, particularly those support the first position—that age mate prefer- for age, are deeply important for understanding ences profoundly influence actual mating behav- human life. ior. This mating behavior ranges widely from ac- tual responses in online dating sites to brideprice paid, engagement rings purchased, actual age dif- References ferences between brides and grooms, causes of divorces, and remarriage probabilities after di- Alcock, J. (2013). Animal behavior: An evolutionary This document is copyrighted by the American Psychological Association or one of its allied publishers. vorce. We suggest that few if any other psycho- approach. Sunderland, MA: Sinauer Associates. This article is intended solely for the personal use of the individuallogical user and is not to be disseminated broadly. proclivities have real-world behavioral Andersson, M. (1994). Sexual selection. Princeton, consequences as broadly and powerfully empiri- NJ: Princeton University Press. cally documented as age mate preferences. Antfolk, J., Salo, B., Alanko, K., Bergen, E., Corander, J., Sandnabba, N. K., & Santtila, P. Implications for mating and human (2015). Women’s and men’s sexual preferences affairs. The current findings also demonstrate and activities with respect to the partner’s age: the profound importance of human mating to Evidence of female choice. Evolution and Human psychology and human affairs. Our ideal mate Behavior, 36, 73–79. http://dx.doi.org/10.1016/j preferences do not merely dictate who we want, .evolhumbehav.2014.09.003 but extend to and pervade our lives. Age mate Arnqvist, G., & Rowe, L. (2005). Sexual conflict. preferences affect who we marry and with Princeton, NJ: Princeton University Press. 154 CONROY-BEAM AND BUSS

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