Evolutionary Psychology PDF - Challenges of Sex and Mating

170 ChALLENGES OF SEx AND MATiNG Extramarital Afairs Men in most cultures pursue extramarital sex more often than do their wives. The Kinsey study, for example, estimated that 50 percent of men had extramarital afairs, whereas only 26 percent of women had them (Kinsey, Pomeroy, & Martin, 1948, 195...

170 ChALLENGES OF SEx AND MATiNG Extramarital Afairs Men in most cultures pursue extramarital sex more often than do their wives. The Kinsey study, for example, estimated that 50 percent of men had extramarital afairs, whereas only 26 percent of women had them (Kinsey, Pomeroy, & Martin, 1948, 1953). Anthropologist Thomas Gregor described the sexual feelings of Amazonian Mehinaku men in this way: “Women’s sexual attractiveness varies from ‘favorless’ (mana) to the ‘delicious’ (awirintya)” (Gregor, 1985, p. 84). Gregor notes that “sad to say, sex with spouses is said to be mana, in contrast with sex with lovers, which is nearly always awirintyapa” (1985, p. 72). Kinsey summed it up best: “There seems to be no question but that the human male would be promiscuous in his choice of sexual partners throughout the whole of his life if there were no social restrictions. The human female is much less interested in a variety of partners” (Kinsey et al., 1948, p. 589). Prostitution Prostitution, the relatively indiscriminate exchange of sexual services for economic proft, is another refection of men’s greater desire for casual sex (Symons, 1979). Prostitution occurs in every society that has been thoroughly studied, from the Azande in Africa to the Zuni in North America (Burley & Symanski, 1981). Within the United States, estimates of the number of active prostitutes range from 100,000 to 500,000. Tokyo has more than 130,000 prostitutes, Poland 230,000, and Addis Ababa in Ethiopia 80,000. In Germany, there are 50,000 legally registered prostitutes and triple that number working illegally. In all cultures, men are overwhelmingly the consumers. Kinsey found that 69 percent of American men had solicited a prostitute, and for 15 percent, prostitution was a regular sexual outlet. The numbers for women were so low that they were not even reported as a percentage of the sexual outlet of women (Kinsey et al., 1948, 1953). Hook-Up Behavior, Friends With Benefts, and Snapchat A third source of behavioral evidence comes from studies of hooking up and friends with benefts. “Hooking up” typically refers to spontaneous sexual interactions in which the participants are not in a traditional romantic relationship and there is no explicit promise of any future intimate relationship (Garcia & Reiber, 2008). “Friends with benefts” (FWB), in contrast, typically refers to a blend of traditional friendship with the “benefts” referring to having sex, but with no implied commitment to a romantic relationship (Owen & Fincham, 2010). More men than women try to initiate hooking up (Garcia & Reiber, 2008) and are more likely than women to report having at least one FWB. Although both women and men obviously engage in these forms of sexual activity, their motivation for doing so appears to difer. Men more than women report that their “ideal outcome” of hooking up is “further hook-ups.” Women more than men report that their “ideal outcome” would be a “traditional romantic relationship.” This fnding might explain why more men than women report FWB—although the means have to be identical for the sexes, men are more likely to construe a particular relationship as FWB, whereas women may perceive it as the early stage of a romantic relationship. Women also report feelings of more regret, feelings of being “used,” and depression following hook-ups or one-night stands (Campbell, 2008). A recent study analyzed the use of Snapchat, a social media app that allows posting of photos and videos, but these last only 10 seconds before disappearing (Moran, Salerno, & Wade, 2018). Men were more likely than women to use Snapchat to seek sexual hook-ups. Similar sex diferences have been discovered in studies of motivations for using the online dating app Tinder (Sumter, Vandenbosch, & Ligtenberg, 2017). Although there are important individual diferences (some women just want sex; some men hope that it will lead to long-term romance), these sex diferences provide another source of behavioral evidence for a fundamental diference in men’s and women’s sexual psychology of short-term mating. Physiological, psychological, and behavioral evidence all point to a long evolutionary history in which short-term mating has been part of the human strategic repertoire (see Table 6.1). 6 ShORT-TERM SExuAL STRATEGiES Table 6.1 Clues to Ancestral Non-Monogamous Mating behavioral Clues Extramarital afairs Prostitution Hook-ups Friends with benefts Tactics for avoiding entangling commitments Physiological Clues Sperm volume Variations in sperm insemination Psychological Clues Desire for sexual variety Desire to seek sex sooner Lowering of standards Attraction-reduction efect Sexual regret at missed opportunities Closing time phenomenon Sexual fantasies Sex drive Sexual attraction to cues to sexual exploitability Women’s Short-Term Mating In this section, we turn to women. First, we consider the evidence that women engage in short-term mating and likely have done so over the long course of human evolutionary history. Second, we consider hypotheses about the adaptive benefts ancestral women might have accrued from short-term mating. Third, we examine the costs of short-term mating for women. Finally, we examine the empirical evidence for the various hypotheses that have been advanced to account for women’s short-term mating. Evidence for Women’s Short-Term Mating Evolutionary theories of human mating, as we have seen, have emphasized the tremendous reproductive benefts to men of short-term mating (e.g., Kenrick et al., 1990; Symons, 1979; Trivers, 1972). Over human evolutionary history, the reproductive benefts of short-term mating for men would have been large and direct in the form of additional children. Perhaps because of the elegance of parental investment theory and the extensive empirical support for it, many theorists have overlooked a fundamental fact about short-term mating: Mathematically, the number of short-term matings must be identical, on average, for men and women (assuming an equal ratio of men to women in the mating pool). Every time a man has a casual sexual encounter with a woman he has never met, the woman is simultaneously having a casual sexual encounter with a man she has never met. If ancestral women never engaged in short-term mating, men could not have evolved a powerful desire for sexual variety (Smith, 1984). That desire, if matings were consensual rather than forced, required the existence of some willing women some of the time. And if ancestral women 171 ChALLENGES OF SEx AND MATiNG 172 willingly and recurrently engaged in short-term mating, it would defy evolutionary logic if there were no benefts to women of doing so. In fact, there are some clues, starting with the physiology of the female orgasm, that ancestral women did engage in short-term mating. Orgasm in Women The physiology of women’s orgasm provides one clue to an evolutionary history of short-term mating. Once it was thought that a woman’s orgasm functioned to make her sleepy and keep her reclined, thereby decreasing the likelihood that sperm would fow out and increasing the likelihood she would conceive. But if the function of orgasm were to keep the woman reclined so as to delay fowback, then more sperm would be retained. That is not the case. Rather, there is no link between the timing of the fowback and the number of sperm retained (Baker & Bellis, 1995). Women discharge roughly 35 percent of sperm within 30 minutes of the time of insemination, averaged across all instances of intercourse. If the woman has an orgasm, however, she retains 70 percent of the sperm, ejecting only 30 percent. This 5 percent diference is not large, but if it occurred repeatedly, in woman after woman, generation after generation, it could add up to a large selection pressure over evolutionary time. Lack of an orgasm leads to the ejection of more sperm. This evidence is consistent with the hypothesis that a woman’s orgasm functions to draw the sperm from the vagina into the cervical canal and uterus, increasing the probability of conception (Puts et al., 2012). The number of sperm a woman retains is also linked with whether she is having an afair. Women time their adulterous liaisons in a way that is reproductively detrimental to their husbands. In a nationwide sex survey of 3,679 women in Britain, all women recorded their menstrual cycles as well as the timing of their copulations with their husbands and, if they were having afairs, with their lovers. It turned out that women having afairs time their copulations, most likely unconsciously, to coincide with the point in their menstrual cycle when they were most likely to be ovulating and hence were most likely to conceive (Baker & Bellis, 1995). Furthermore, women who are having afairs are more likely to be orgasmic with their afair partner than with their regular partner (Buss, 2016b). Other studies fnd that women are especially likely to experience sexual orgasm with men who are masculine and physically attractive—qualities women typically desire in short-term mating (Puts, Welling, Burriss, & Dawood, 2012). Behavioral Evidence The behavioral evidence also suggests that women in all but the most restrictive societies sometimes engage in extramarital sexual unions. In the United States, studies yield an afair rate ranging from 20 to 50 percent for married women (Athanasiou, Shaver, & Tavris, 1970; Buss, 1994b; Glass & Wright, 1992; Hunt, 1974; Kinsey et al., 1948, 1953). Afairs have also been documented, despite the shroud of secrecy that surrounds them, in dozens of tribal societies including the Ache of Paraguay (Hill & Hurtado, 1996), the Yanomamö of Venezuela (Chagnon, 1983), the Tiwi of Australia (Hart & Pilling, 1960), the !Kung of Botswana (Shostak, 1981), and the Mehinaku of Amazonia (Gregor, 1985). Studies of college women reveal that they do have sex with their opposite-sex friends (26 percent according to one study), as well as attempting to initiate hook-ups (65 percent) (Garcia & Reiber, 2008). Modern cultural and tribal behavioral evidence, in short, does not suggest that women invariably pursue a monogamous longterm mating strategy all of the time. 6 ShORT-TERM SExuAL STRATEGiES 173 Hypotheses About the Adaptive Benefts to Women of Short-Term Mating For short-term sexual psychology to evolve in women, there must have been adaptive benefts associated with casual sex in some circumstances. What might those benefts have been? Five classes of benefts have been proposed: resources, genes, mate switching, short-term for long-term mating goals, and mate manipulation (Greiling & Buss, 2000) (Table 6.2). Resource Hypotheses One beneft of short-term mating is resource accrual (Symons, 1979). Women could engage in short-term mating in exchange for meat, goods, or services. An ancestral woman might have been able to obscure the actual paternity of her ofspring through several short-term matings and thus elicit resources from two or more men (Hrdy, 1981). According to this paternity confusion hypothesis, each man might be willing to ofer some investment in the woman’s children on the chance that they are genetically his own. Another possible resource is protection (Smith, 1984; Smuts, 1985). Men typically provide protection to their mates and children, including defense against predators and aggressive men. Because a primary mate cannot always be around to defend and protect a woman, she might gain added protection by consorting with another man. Finally, Smith (1984) proposed the status-enhancement hypothesis of short-term mating. A woman might be able to elevate her social standing among her peers or gain access to a higher social circle by a temporary liaison with a high-status man. Clearly women might gain a variety of tangible and intangible resources through short-term mating. Table 6.2 Hypothesized Benefts to Women: Short-Term Mating Hypothesis Resource Investment via paternity confusion Immediate economic resources Protection through “special friendships” Status elevation Genetic beneft Better or “sexy son” genes Diverse genes Mate Switching Mate expulsion Mate replacement Mate insurance [backup] Short-Term for long-Term Goal Sex to evaluate long-term mate potential Clarifying mate preferences Honing skills of mate attraction Mate Manipulation Increasing commitment of long-term mate Revenge as deterrence author Hrdy (1981) Symons (1979) Smuts (1985) Smith (1984) Fisher (1958) Smith (1984) Greiling and Buss (2000) Symons (1979) Smith (1984) Buss and Schmitt (1993) Greiling and Buss (2000) Miller (personal communication, 1991) Greiling (1995) Symons (1979) Source: Greiling, H., & Buss, D. M. (2000). Women’s sexual strategies: The hidden dimension of short-term extra-pair mating. Personality and Individual Diferences, 28, 929–963. ChALLENGES OF SEx AND MATiNG 174 Genetic Beneft Hypotheses Another class of benefts can be called genetic benefts. The frst is the most obvious— enhanced fertility. If a woman’s regular mate is infertile or impotent, a short-term mate might provide a fertility backup to aid in conception. Second, a short-term mate might provide superior genes compared with a woman’s regular mate, especially if she has an afair with a healthy or high-status man. These genes might give her ofspring better chances for survival or reproduction (Smith, 1984). One version of this is known as the sexy son hypothesis (Fisher, 1958). By mating with an especially attractive man, a woman might be able to bear a son who is especially attractive to women in the next generation. Her son thus might have increased sexual access, produce more children, and hence might provide his mother with additional grandchildren. Third, short-term mates might provide a woman with diferent genes compared with those of her regular mate, thus enhancing the genetic diversity of her children—perhaps a hedge against environmental change (Smith, 1984) or environments containing high levels of disease-causing pathogens (Hill, Prokosch, & DelPriore, 2015). Mate Switching Hypotheses A third class of benefts pertains to mate switching. Sometimes, a woman’s husband stops bringing in resources, starts abusing her, or otherwise declines in his value to her as a mate (Betzig, 1989; Fisher, 1992; Smith, 1984). Ancestral women might have benefted from short-term mating to cope with this adaptive problem. There are several variants of this hypothesis. According to the mate expulsion hypothesis, having a short-term afair would help the woman to get rid of her long-term mate. Because men in many cultures often divorce wives who have afairs (Betzig, 1989), having an afair would be an efective means for the woman to initiate a breakup. Another variant of this hypothesis suggests that a woman might simply fnd a man who is better than her husband and so initiate a short-term encounter as a means of “trading up” to a higher-quality mate (Buss, Goetz, Duntley, Asao, & Conroy-Beam, 2017). Short-Term for Long-Term Goals Hypotheses Another hypothesis is that women use short-term mating as a means to assess and evaluate prospective long-term mates (Buss & Schmitt, 1993). Engaging in short-term mating allows a woman to clarify the qualities she desires in a long-term mate, evaluate her compatibility with a particular man (e.g., sexual compatibility), and reveal any hidden costs he might carry (e.g., existing children, deception). Two clear predictions follow from this hypothesis: Women will dislike in a short-term mate (1) any signals that the man is already in an existing relationship, because this would lower the odds of her successfully attracting him as a long-term mate, and (2) the attribute of promiscuity, since this would signal that he is pursuing a truly short-term rather than long-term mating strategy. Other variants of the short-term for long-term goals hypothesis are that a woman uses short-term mating to clarify the qualities she truly desires in a long-term mate (Greiling & Buss, 2000) or to hone her skills of attraction and seduction so that she can eventually attract a more desirable long-term mate. Mate Manipulation Hypotheses A ffth class of benefts involves manipulating her mate. By having an afair, a woman might be able to gain revenge on her husband for his infdelity, possibly deterring him from future 6 ShORT-TERM SExuAL STRATEGiES infdelities (Symons, 1979). Alternatively, a woman might be able to increase the commitment of her regular mate if he saw with stark evidence that other men were seriously interested in her (Greiling & Buss, 2000). Costs to Women of Short-Term Mating Women sometimes incur more severe costs than men as a consequence of short-term mating. Women risk impairing their desirability as a long-term mate if they develop reputations for promiscuousness, because men prize fdelity in potential wives. Women known to be promiscuous sufer reputational damage even in relatively promiscuous cultures, such as among the Swedes and the Ache Indians. Lacking a long-term mate to ofer physical protection, a woman who adopts an exclusively short-term sexual strategy is at greater risk of physical and sexual abuse. Although women in marriages are also subjected to battering and even rape from their husbands, the alarming statistics on the incidence of date rape, which run as high as 15 percent in studies of college women, support the contention that women not in long-term relationships are also at considerable risk (Muehlenhard & Linton, 1987). The fact that women participating in the study of short-term and long-term partners intensely dislike lovers who are physically abusive, violent, and mentally abusive suggests that women may be aware of the risks of abuse (Buss & Schmitt, 1993). Mate preferences, if judiciously applied to avoid potentially dangerous men, can minimize these risks. The unmarried woman in the pursuit of casual sex risks getting pregnant and bearing children without the beneft of an investing man. In ancestral times, such children would likely have been at much greater risk of disease, injury, and death. Some women commit infanticide without the presence of an investing man. In Canada, for example, single women delivered only 12 percent of the babies born between 1977 and 1983 but committed just over 50 percent of the 64 maternal infanticides (Daly & Wilson, 1988). The higher infanticide rates among unmarried women occur across cultures as well, such as among the Buganda of Africa. But even infanticide does not cancel the substantial costs of 9 months of gestation, reputational damage, and lost mating opportunities that women incur. An unfaithful married woman risks the withdrawal of resources by her husband. From a reproductive standpoint, she may be wasting valuable time in an extramarital liaison. Furthermore, she risks the possibility of increasing the sibling competition among her children, who may have weaker ties with each other because they were fathered by diferent men. Women more than men sufer damage to their status and reputation as a consequence of short-term sex (Buss, 2013). Finally, women risk contracting sexually transmitted diseases from short-term mating—a risk that is greater for women than for men per act of sex (Symons, 1993). Short-term mating imposes hazards for both sexes. But because there might be large benefts as well, women and men may have evolved psychological mechanisms to select contexts in which costs are minimized and benefts maximized. Empirical Tests of Hypothesized Benefts to Women Several researchers have discovered that women who engaged in short-term mating place a premium on the man’s physical attractiveness, a fnding consistent with the good genes and the sexy son hypotheses (Buss & Schmitt, 1993; Gangestad & Simpson, 1990; Kenrick, Sadalla, Groth, & Trost, 1990). Women also seem to elevate the importance they place on immediate resources in the short-term mating context (Buss & Schmitt, 1993). Women say that they desire a short-term mate who has an extravagant lifestyle, who spends a lot of money on them early on, and who gives them gifs early in the relationship. These fndings support the resource accrual hypothesis. 175