15-7 How might an evolutionary psychologist explain male-female differences in sexuality and mating preferences?

Having faced many similar challenges throughout history, males and females have adapted in similar ways: We eat the same foods, avoid the same predators, and perceive, learn, and remember similarly. It is only in those domains where we have faced differing adaptive challenges—most obviously in behaviors related to reproduction—that we differ, say evolutionary psychologists.

And differ we do. Consider sex drives. Both men and women are sexually motivated, some women more so than many men. Yet, on average, who thinks more about sex? Masturbates more often? Initiates more sex? Views more pornography? The answers worldwide—Men, men, men, and men (Baumeister et al., 2001; Lippa, 2009; Petersen & Hyde, 2010). No surprise, then, that in one BBC survey of more than 200,000 people in 53 nations, men everywhere more strongly agreed that “I have a strong sex drive” and “It doesn’t take much to get me sexually excited” (Lippa, 2008).

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And there are other sexuality differences between males and females (Hyde, 2005; Petersen & Hyde, 2010; Regan & Atkins, 2007). To see if you can predict some of these differences, take the quiz in TABLE 5.2.

(ANSWERS)

Compared with lesbians, gay men (like straight men) report more responsiveness to visual sexual stimuli, and more concern with their partner’s physical attractiveness (Bailey et al., 1994; Doyle, 2005; Schmitt, 2007; Sprecher et al., 2013). Gay male couples also report having sex more often than do lesbian couples (Peplau & Fingerhut, 2007). And they report more interest in uncommitted sex. Although men are roughly two-thirds of the U.S. gay population, they are only 36 percent of same-sex legal partners via marriage, civil union, or domestic partnership (Badgett & Mallory, 2014).

Natural selection is nature selecting traits and appetites that contribute to survival and reproduction. Evolutionary psychologists use this principle to explain how men and women differ more in the bedroom than in the boardroom. Our natural yearnings, they say, are our genes’ way of reproducing themselves. “Humans are living fossils—collections of mechanisms produced by prior selection pressures” (Buss, 1995).

Why do women tend to be choosier than men when selecting sexual partners? Women have more at stake. To send her genes into the future, a woman must—at a minimum—conceive and protect a fetus growing inside her body for up to nine months. No surprise then, that heterosexual women prefer partners who will offer their joint offspring support and protection. They prefer stick-around dads over likely cads. Heterosexual women are attracted to tall men with slim waists and broad shoulders—all signs of reproductive success (Mautz et al., 2013). And they prefer men who seem mature, dominant, bold, and affluent (Asendorpf et al., 2011; Gangestad & Simpson, 2000; Singh, 1995). One study of hundreds of Welsh pedestrians asked people to rate a driver pictured at the wheel of a humble Ford Fiesta or a swanky Bentley. Men said a female driver was equally attractive in both cars. Women, however, found a male driver more attractive if he was in the luxury car (Dunn & Searle, 2010). When put in a mating mindset, men buy more showy items, express more aggressive intentions, and take more risks (Baker & Maner, 2009; Griskevicius et al., 2009; Shan et al., 2012; Sundie et al., 2011).

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The data are in, say evolutionists: Men pair widely; women pair wisely. And what traits do straight men find desirable? Some, such as a woman’s smooth skin and youthful shape, cross place and time, and they convey health and fertility (Buss, 1994). Mating with such women might increase a man’s chances of sending his genes into the future. And sure enough, men feel most attracted to women whose waists (thanks to their genes or their surgeons) are roughly a third narrower than their hips—a sign of future fertility (Perilloux et al., 2010). Even blind men show this preference for women with a low waist-to-hip ratio (Karremans et al., 2010). Men are most attracted to women whose ages in the ancestral past (when ovulation began later than today) would be associated with peak fertility (Kenrick et al., 2009). Thus, teen boys are most excited by a woman several years older than themselves, mid-twenties men prefer women around their own age, and older men prefer younger women. This pattern consistently appears across European singles ads, Indian marital ads, and marriage records from North and South America, Africa, and the Philippines (Singh, 1993; Singh & Randall, 2007).

There is a principle at work here, say evolutionary psychologists: Nature selects behaviors that increase the likelihood of sending one’s genes into the future. As mobile gene machines, we are designed to prefer whatever worked for our ancestors in their environments. They were genetically predisposed to act in ways that would leave grandchildren. Had they not been, we wouldn’t be here. As carriers of their genetic legacy, we are similarly predisposed.

15-8 What are the key criticisms of evolutionary explanations of human sexuality, and how do evolutionary psychologists respond?

Most psychologists agree that natural selection prepares us for survival and reproduction. But critics say there is a weakness in evolutionary psychology’s explanation of our mating preferences. Let’s consider how an evolutionary psychologist might explain the findings in a startling study (Clark & Hatfield, 1989), and how a critic might object.

Participants were approached by a “stranger” of the other sex (someone working for the experimenter). The stranger remarked, “I have been noticing you around campus. I find you to be very attractive,” and then sometimes asked, “Would you go to bed with me tonight?” What percentage of men and women do you think agreed to this offer? The evolutionary explanation of sexuality predicts that women will be choosier than men in selecting their sexual partners and will be less willing to hop in bed with a complete stranger. In fact, not a single woman agreed—but 70 percent of the men did. A repeat of this study produced a similar result in France (Guéguen, 2011). The research seemed to support an evolutionary explanation.

Or did it? Critics note that evolutionary psychologists start with an effect—in this case, the survey result showing that men were more likely to accept casual sex offers—and work backward to explain what happened. What if research showed the opposite effect? If men refused an offer for casual sex, might we not reason that men who partner with one woman for life make better fathers, whose children more often survive?

Other critics ask why we should try to explain today’s behavior based on decisions our distant ancestors made thousands of years ago. Don’t cultural expectations also bend the genders? Alice Eagly and Wendy Wood (1999; Eagly, 2009) point to the smaller behavioral differences between men and women in cultures with greater gender equality, for example. Such critics believe social learning theory offers a better, more immediate explanation for these results. Women learn social scripts—their culture’s guide to how people should act in certain situations. By watching and imitating others in their culture, they may learn that sexual encounters with strangers can be dangerous, and that casual sex may not offer much sexual pleasure (Conley, 2011). This alternative explanation of the study’s effects proposes that women react to sexual encounters in ways that their modern culture teaches them. Similarly, men are influenced by social scripts teaching the lesson that “real men” take advantage of every opportunity to have sex.

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A third criticism focuses on the social consequences of accepting an evolutionary explanation. Are heterosexual men truly hard-wired to have sex with any woman who approaches them? If so, does it mean that men have no moral responsibility to remain faithful to their partners? Does this explanation excuse men’s sexual aggression—“boys will be boys”—because of our evolutionary history?

Evolutionary psychologists agree that much of who we are is not hard-wired. “Evolution forcefully rejects a genetic determinism,” insisted one research team (Confer et al., 2010). Genes are not destiny. And evolutionary psychologists remind us that men and women, having faced similar adaptive problems, are far more alike than different. Natural selection has prepared us to be flexible. We humans have a great capacity for learning and social progress. We adjust and respond to varied environments. We adapt and survive, whether we live in the Arctic or the desert.

Evolutionary psychologists also agree with their critics that some traits and behaviors, such as suicide, are hard to explain in terms of natural selection (Barash, 2012; Confer et al., 2010). But they ask us to remember evolutionary psychology’s scientific goal: to explain behaviors and mental traits by offering testable predictions using principles of natural selection. We can, for example, scientifically test hypotheses such as this: Do we tend to favor others to the extent that they share our genes or can later return our favors? (The answer is Yes.) They also remind us that studying how we came to be need not dictate how we ought to be. Understanding our tendencies can help us overcome them.