Evolutionary Psychology ch 5_1-6.pdf

ChaPter 5 Men’s Long-Term Mating Strategies Learning Objectives Afer studying this chapter, the reader will be able to: ■ list seven benefts men gain from commitment and marriage. ■ analyze why ancestral men faced the adaptive problem of identifying a woman’s fertility. ■ Explain the evolution...

ChaPter 5 Men’s Long-Term Mating Strategies Learning Objectives Afer studying this chapter, the reader will be able to: ■ list seven benefts men gain from commitment and marriage. ■ analyze why ancestral men faced the adaptive problem of identifying a woman’s fertility. ■ Explain the evolutionary theory of men’s evolved standards of female beauty. ■ describe why men face the problem of “paternity uncertainty.” ■ compare and contrast the two theories for the links between men’s testosterone and their mating strategies. ■ identify four sources of evidence that men’s evolved mate preferences infuence actual mating behavior. Why does a particular maiden turn our wits so upside-down? —William James (1890) For selection to produce psychological mechanisms in men to seek marriage and commitment, it is reasonable to assume that there were adaptive advantages to long-term mating under some circumstances. This chapter examines the logic and evidence of men’s long-term mating strategies. We start with the theoretical background for the evolution of men’s mate preferences. Then we examine the content of men’s mate preferences. The fnal section explores the efects of diferent social and ecological contexts on men’s long-term mating strategies. Theoretical Background for the Evolution of Men’s Mate Preferences This section covers the theoretical background for two topics. The frst is why men would commit or marry at all—what are the potential adaptive benefts that ancestral men could have gained from commitment and marriage? The second topic deals with complexities surrounding the content of men’s desires and how selection might have fashioned specifc mate preferences in men. Why Men Might Beneft From Commitment and Marriage One solution to the puzzle of why men would seek marriage comes from the ground rules set by women. Because it is clear that many ancestral women required reliable signs of male commitment before consenting to sex, men who failed to commit might have failed to attract any women at all. Another beneft of marriage is an increase in the quality of the woman a man would be able to attract. Men who are willing to promise long-term resources, protection, and investment in 5 MEN’S LONG-TERM MATiNG STRATEGiES children are appealing to women, as we saw in Chapter 4, so men who are willing to commit to the long term have a wider range of women from which to choose. Willing men attract desirable women because women typically desire lasting commitment, and highly desirable women are in the best position to get what they want. A third potential beneft is an increase in the odds that the man is the father of the children a woman bears. Through marriage, a man gains repeated sexual access—in many cases, exclusive sexual access. Without recurrent or exclusive access, his certainty in paternity would be jeopardized. Thus, men who marry gain the reproductive beneft of an increase in paternity certainty. A fourth potential beneft of marriage would have been an increase in the survival of the man’s children. In human ancestral environments, it is likely that infants and young children more frequently died without the prolonged investment from two parents or related kin (Hill & Hurtado, 1996). Among the Ache Indians of Paraguay, for example, children without an investing father sufer a death rate more than 10 percent higher than children whose fathers remain alive. Over human evolutionary history, even children who did survive without their father’s investment might have sufered from the absence of his teaching and political alliances, because both of these assets help to solve survival and mating problems later in life. Fathers in many cultures past and present have had a strong hand in arranging benefcial marriages for their sons and daughters. Men also beneft from marriage by an increase in status. In many cultures, males are not considered to have achieved true manhood until they have married. Increased status, in turn, can bring a bounty of benefts, including better resources for his children and additional mates (see Chapter 12). By marrying, a man also gains access to coalitional allies through his wife’s family, which provide additional reproductively relevant benefts such as greater protection for his family and more social allies in group-on-group conficts. In modern environments, perhaps more than ancestral environments, marriage sometimes allows a man to gain access to his partner’s resources and status, since some modern women such as Jennifer Lopez and Katy Perry have both assets in abundance. Finally, there is compelling evidence that married men live longer than single men (Gellatly & Strömer, 2017). This is especially true of men married to younger women, since the age gap predicts men’s longevity. It’s possible that women choose to marry men who have high-potential longevity, but it’s also possible that marriage itself has a causal efect on men’s health, helping them to live longer. In summary, there are nine potentially powerful adaptive benefts that would have accrued to men willing to make the commitment of marriage: (1) increased odds of succeeding in attracting a man, (2) increased ability to attract a more desirable mate, (3) increased paternity certainty, (4) increased survival of his children, (5) increased reproductive success of children accrued through paternal investment, (6) increased social status, (7) added coalitional allies, (8) access to his partner’s resources and status, and (9) increased lifespan. The Problem of Assessing a Woman’s Fertility or Reproductive Value To be reproductively successful, ancestral men would beneft from marrying women with the capacity to bear children. A woman with the capacity to bear many children obviously would have been more benefcial in reproductive currencies than a woman capable of bearing few or none. Men cannot observe a woman’s reproductive value directly, and so selection could only have fashioned preferences in men for observable qualities that are reliably correlated with reproductive value. When we compare humans with the closest primate relative, the chimpanzee, we see a startling discontinuity in the female advertisement of reproductive status. When the female chimpanzee is capable of conceiving, she goes into a phase called estrus—the time during which she releases her eggs and shows maximal sexual receptivity. The receptivity of estrus is usually advertised by bright-red, swollen genitals and scents that are highly attractive to chimpanzee males. Most, 131 132 ChALLENGES OF SEx AND MATiNG although not all, of the sexual activity among the chimpanzees takes place during the estrus phase, when the female is most likely to conceive. Humans show a markedly diferent form of mating. First, women’s ovulation is relatively concealed or cryptic. Unlike chimpanzee females, when women release their eggs for potential fertilization, the event is not accompanied by a pronounced genital swelling or clearly detectable scents. Second, sexual activity among most humans occurs throughout the woman’s ovulation cycle. Unlike the chimpanzee, sexual activity is not concentrated during the phase in which the female is most likely to conceive. The transition from advertised estrus to concealed ovulation posed a poignant adaptive problem for human ancestral males. When ovulation is not advertised, how could males discern a female’s reproductive status? The concealment of ovulation, in short, shifted the problem from one of detecting when a woman was ovulating to one of determining which women were likely to be capable of conceiving children—the problem of determining a woman’s reproductive value or fertility. Reproductive value refers to the number of children a person of a given age and sex is likely to have in the future. A woman who is 17 years old, for example, has a higher reproductive value than a woman who is 37 because, on average, the younger woman is likely to bear more children in the future than is the older woman. Individual women may, of course, defy these averages. The 17-year-old might decide never to have children, and the 37-year-old could have triplets. The key is that reproductive value refers to the average expected future reproduction of a person of a given age and sex (see Figure 5.1). Reproductive value difers from fertility, which is defned as actual reproductive performance, measured by the number of viable ofspring produced. In human populations, women in their mid-20s tend to produce the most viable children, and so fertility among humans reaches a peak in the mid-20s. The diferences between fertility and reproductive value can be illustrated by contrasting two females, ages 17 and 25. The younger female has a higher reproductive value because her future reproduction is expected to be higher. The 25-year-old female, in contrast, would be more fertile because women in their mid-20s produce more children, on average, than do women in their teens. The solution to the problem of detecting fertility or reproductive value, however, is more difcult than it might appear. The number of children a woman is likely to bear in her lifetime is not stamped on her forehead. It is not encoded in her social reputation. Even women themselves lack direct knowledge of their reproductive value. Ancestral men, however, could have evolved adaptations sensitive to observable qualities of a woman that are correlated with underlying Figure 5.1 Typical Reproductive Value Curve for Women The fgure shows the number of children a woman of a given age is likely to have, on average, in the future. 5 MEN’S LONG-TERM MATiNG STRATEGiES reproductive value. Two potentially observable sets of cues would have included a woman’s youth and her health (Symons, 1979; Williams, 1975). Old or unhealthy women clearly could not reproduce as much as young, healthy women. But precisely which observable qualities of a woman might signal youth and health? And do men’s desires in a marriage partner focus heavily on her reproductive capacity? The Content of Men’s Mate Preferences In many ways men’s long-term mate preferences are similar to those of women. Like women, men express a desire for partners who are intelligent, kind, understanding, and healthy (Buss, 2016b). Intelligent long-term mates ofer a bounty of benefts—skill at solving mutually relevant problems of survival, adeptness at childrearing, skill in navigating social hierarchies, and even good genes that can be transmitted to children. Kind and understanding partners tend to be empathic, good at social mind reading, and highly cooperative as long-term partners. Men who select healthy mates beneft from their ability to thrive in adverse circumstances, remain energetic in accomplishing the tasks of everyday living, and pass on genes for good health to their children. Also, like women, men look for partners who share their values and are similar to them in attitudes, personality, and religious beliefs. These shared qualities maximize cooperation in long-term mateships and minimize confict. Standards of Beauty Emerge Early in Life Most traditional psychological theories of attraction have assumed that standards of attractiveness are learned gradually through cultural transmission and therefore do not emerge clearly until a child is 3 or 4 years old or even later (Berscheid & Walster, 1974; Langlois et al., 1987). However, psychologist Judith Langlois and her colleagues have overturned this conventional wisdom by studying infants’ social responses to faces (Langlois, Roggman, & Reiser-Danner, 1990). Adults evaluated color slides of White and Black female faces for their attractiveness. Then infants 2 to 3 months and 6 to 8 months old were shown pairs of these faces that difered in degree of attractiveness. Both younger and older infants gazed longer at the more attractive faces, suggesting that standards of beauty apparently emerge quite early in life. In a second study, 12-month-old infants played signifcantly longer with facially attractive dolls than with unattractive dolls. This evidence challenges the commonly held view that the standards of attractiveness are learned through gradual exposure to current cultural models. No training seems necessary for these standards to emerge. Standards of Beauty Are Consistent Across Cultures The constituents of beauty are neither arbitrary nor culture bound. When psychologist Michael Cunningham asked people of diferent races to judge the facial attractiveness of Asian, Hispanic, Black, and White women in photographs, he found tremendous consensus about who is and who is not considered good-looking (Cunningham, Roberts, Wu, Barbee, & Druen, 1995). The average correlation between groups in their ratings of the attractiveness of these photographs was +.93. In a second study by the same investigators, Taiwanese subjects agreed with the other groups in the average ratings of attractiveness (r = +.91). Degree of exposure to Western media did not afect the judgments of attractiveness in either study. In a third study, Blacks and Whites showed tremendous agreement about which women’s faces were most and least attractive (r = +.94). Consensus has also been found among Chinese, Indian, and English subjects; between South Africans and North Americans; and between Russians, Ache Indians, and Americans (Cross & Cross, 1971; Jackson, 1992; Jones, 1996; Morse, Gruzen, & Reis, 1976; Thakerar & Iwawaki, 1979). 133 ChALLENGES OF SEx AND MATiNG 134 So standards of beauty seem to emerge early in life and are to some extent consistent across cultures. Why would this be? In some domains, ancestral men confronted a diferent set of adaptive mating problems than did ancestral women, and so their descendants are predicted to hold a somewhat diferent set of mate preferences as adaptive solutions. These preferences start with one of the most powerful cues to a woman’s reproductive status—her age. Preference for Youth Youth is a critical cue because a woman’s reproductive value declines steadily as she moves past age 20. By the age of 40, a woman’s reproductive capacity is low, and by 50, it is essentially zero. Men’s preferences capitalize on this. Within the United States, men uniformly express a desire for mates who are younger than they are. Men’s preference for youthful partners is not limited to Western cultures. Nigerian, Indonesian, Iranian, and Indian men express similar preferences. Without exception, in every one of the 37 societies examined in an international study on mate selection, men preferred younger wives. Nigerian men who were 23 years old, for example, expressed a preference for wives who were 6.5 years younger (Buss, 1989a). Croatian men who were 21.5 years old expressed a desire for wives who were approximately 19 years old. Chinese, Canadian, and Colombian men shared with their Nigerian and Croatian brethren a powerful desire for young women. On average, men from the 37 cultures expressed a desire for wives approximately 2.5 years younger than themselves (refer to Figure 4.4, page 111). Interestingly, an eye-tracking study found that both male and female judges exhibited a larger number of eye fxations and longer dwell time when viewing female faces perceived to be younger—suggesting greater “attentional adhesion” to young female faces (Fink et al., 2008). Although men universally prefer younger women as wives, the strength of this preference varies somewhat from culture to culture. Among Scandinavian countries such as Finland, Sweden, and Norway, men prefer their brides to be only 1 or 2 years younger. Men in Nigeria and Zambia prefer their brides to be 6.5 and 7.5 years younger, respectively. In Nigeria and Zambia, which practice polygyny like many cultures worldwide, men who can aford it are legally permitted to marry more than one woman. Because men in polygynous mating systems are typically older than men in monogamous systems by the time they have acquired sufcient resources to attract wives, the larger age diference preferred by Nigerian and Zambian men may refect their advanced age when they acquire wives. A comparison of the statistics ofered in personal ads in newspapers reveals that a man’s age has a strong efect on what he desires. As men get older, they prefer as mates women who are increasingly younger than they are—a fnding replicated in a large study of 21,245 individuals ranging from 18 to 65 (Schwarz & Hassebrauck, 2012). Men in their 30s prefer women who are roughly 5 years younger, whereas men in their 50s prefer women who are 10 to 20 years younger (Kenrick & Keefe, 1992). One evolutionary model predicts that what men desire is not youth per se but rather features of women that are associated with reproductive value or fertility. This perspective leads to a counterintuitive prediction when it comes to the age preferences of adolescent males: Teenage males should prefer women who are slightly older than they are, contrary to the typically observed pattern of men desiring younger partners, because slightly older women have higher fertility than women their own age or women who are younger (Kenrick, Keefe, Gabrielidis, & Cornelius, 1996). To test this prediction, one study (Kenrick et al., 1996) surveyed 103 teenage males and 106 females ranging in age from 12 to 19. The participants received the following instructions: “I’d like you to think for a second about what type of person you would fnd attractive. Imagine you were going on a date with someone” (Kenrick et al., 1996, p. 1505). Each participant was then asked about his or her age limits. The experimenter began by asking, “Would you date someone who was [the subject’s age]?” followed by “How about someone who was [subject’s age minus one]?” If afrmative answers were given, the experimenter then continued until the participant stated that a particular age was too young. 5 MEN’S LONG-TERM MATiNG STRATEGiES The experimenter then asked about the maximum acceptable age of a dating partner. Finally, participants were asked about the ideal age of a dating partner, “the most attractive person you could possibly imagine” (Kenrick et al., 1996, p. 1505). The results yielded three variables: ideal age, minimum age, and maximum age of dating partner desired. Although these teenage males were willing to accept dates with females who were slightly younger, they were far more willing to accept dates with older women. The “most attractive” age mirrors these fndings, with adolescent males expressing a desire for dates who were several years older on average. Interestingly, this fnding occurs despite the fact that these older women expressed little interest in dating younger men. At the youngest ages, teenage males prefer females a few years older than themselves. But with advancing age, men prefer women who are increasingly younger than they are. These data concerning teenagers are important in rendering several alternative explanations less plausible. One explanation for men’s desire for young women, for example, is that young women are easier to control and are less dominant than older women, and men seek to mate with women they can control. If this were the sole reason for men’s preference for young women, however, then we would expect that teenage males would also prefer younger women, but they don’t. Another explanation for men’s desire for young women is based on learning theory. Because women tend to prefer men who are somewhat older, men may have received more reward or reinforcement for seeking dates with younger women. This reinforcement explanation, however, fails to account for the preferences of the teenage males, who prefer older women despite the fact that the interest is rarely reciprocated. Taken together with the cross-cultural data, these fndings lend strong support to an evolutionary psychological explanation: Men desire young women because over evolutionary time, youth has consistently been linked with fertility. This explanation accounts for two facts that all other theories have difculty explaining: First, that men desire women who are increasingly younger than they are as the men themselves get older; second, that teenage males prefer women a few years older than they are, despite the fact that such women rarely reward them for such interest. Nonetheless, an important anomaly remains unexplained by the evolutionary hypothesis. Although men prefer women who are increasingly younger than they are as long-term mates as they get older, the actual age preferences of older men is beyond maximum fertility. Men who are 50, for example, prefer women who are in their mid-30s (in sharp contrast to men’s age preferences for a short-term mate, which remain at the age of peak fertility—see Buunk, Dijkstra, Kenrick, & Warntjes, 2001). There are a few possible explanations. First, older men may have difculty in actually attracting dramatically younger women, and their preferences may refect a compromise between their ideal and what they can get (Buunk et al., 2001). Second, large age discrepancies may create less compatibility, greater marital confict, and more marital instability. Indeed, both the divorce rate and the mate homicide rate rise as a function of the magnitude of the age discrepancy between partners (Daly & Wilson, 1988). Third, modern marriage likely difers from ancestral marriage. In modern marriages, couples spend a great deal of time together, socialize as a couple, and act as companions. Judging from hunter-gatherer groups, ancestral marriages were more likely to involve sharp divisions of labor, with women spending the bulk of their time with children and other women and men hunting and socializing with other men. Thus, the importance of similarity and compatibility for functioning in modern marriages may have created a shift in men’s age preferences above the point of maximum female fertility. Which of these explanations, or which combination, turns out to be correct must await future research. Evolved Standards of Physical Beauty Evolutionary logic leads to a powerful set of expectations for universal standards of beauty. Just as our standards for attractive landscapes embody cues such as water, game, and refuge, mimicking our ancestors’ savanna habitats (Orians & Heerwagen, 1992), our standards for female beauty embody cues to women’s fertility or reproductive value. 135