Beauty is in the adaptations of the beholder.
—DONALD SYMONS, “What Do Men Want?”
WHY MEN WOULD ever commit to just one woman poses a puzzle. Since all an ancestral man needed to do to reproduce was to impregnate a woman, casual sex without commitment would have achieved this goal. For evolution to produce men who desire commitment or marriage and who are willing to devote years of investment to one woman, powerful adaptive advantages to that strategy over one of seeking casual sex, at least under some circumstances, must have been present.
One solution to this puzzle comes from the ground rules set by women. Since it is clear that many ancestral women required reliable signs of male commitment before consenting to sex, men who failed to commit would have suffered on the mating market. They might have failed to attract any women at all. Or perhaps they failed to attract the more desirable women and had to settle for those lower in mate value. Women’s requirements for consenting to sex made it costly for most men to pursue a short-term mating strategy exclusively. In the economics of reproductive effort, the costs of not pursuing a long-term mate would have been prohibitively high for most men, and men would have benefited as their odds of attracting a mate, as well as attracting a more desirable mate, increased with their willingness to commit.
Another way in which men benefited from sustained commitment to one woman was by increasing the odds that he would be the father of any children she bore—upping his probability of genetic paternity. By committing for the long term, men typically gained repeated and exclusive sexual access, and their close proximity put them in a position to fend off potential mate poachers. Without commitment, repeated sex became questionable and paternity more uncertain.
A further benefit of committing to one woman was the increased survival and reproductive success of the man’s children. In human ancestral environments, infants and young children were more likely to die without sustained investment from two parents or related kin.1 Among the Ache of Paraguay, for example, when a man dies in a club fight, the other villagers often make a collective decision to kill his children, even when the children have a living mother. In one case reported by the anthropologist Kim Hill, a boy of thirteen was killed after his father had died in a club fight. Overall, Ache children whose fathers die suffer a death rate more than 10 percent higher than children whose fathers remain alive.
Over human evolutionary history, even children who did survive without the father’s investment would have suffered by missing out on the knowledge he could impart and the political alliances he could bestow. Both of these assets help solve mating problems later in life. Fathers in many cultures past and present have a strong hand in arranging beneficial marriages for their sons and daughters.2 The absence of these benefits challenges the evolutionary fitness of children without fathers. These evolutionary pressures, operating over thousands of generations, gave an advantage to men who pursued a long-term strategy of commitment.
The economics of the mating marketplace typically produces an asymmetry between the sexes in their ability to obtain a desirable mate in a committed as opposed to a temporary relationship.3 Most men can obtain a much more desirable mate if they are willing to commit to a long-term relationship because women typically desire a lasting commitment, and highly desirable women are in the best position to get what they want. In contrast, most women can obtain a much more desirable casual partner by offering sex without requiring commitment, since high-status men are willing to relax their standards and have sex with a variety of women if the short-term hookup carries no commitment. High-status men impose more stringent standards for a partner to whom they are willing to commit.
Men also gain in two other ways by committing. One is an increase in social status. In many cultures, males are not considered “real men” until they have married. Increased status, of course, brings a man other bounties, including better resources for his children and sometimes an increased attractiveness to additional mates. A final benefit of commitment or marriage is the formation of a more expansive coalitional network that includes his spouse’s friends and kin. Men, in short, have much to gain by committing to one woman.
Much of what men want in a long-term mate coincides with what women want. Like women, men want committed partners who are intelligent, kind, dependable, emotionally stable, and healthy. For men as well as for women, these qualities are linked with mates who will make excellent partners, excellent allies, and excellent parents. These qualities could also signal good genetic material and low mutation loads, that is fewer copying errors within the partner’s genome—qualities that make for healthier and more robust children.
But men face an adaptive problem not faced by women, at least not as poignantly—choosing a fertile partner. To be reproductively successful, the most obvious criterion would be a woman’s ability to bear children. A woman with high reproductive capacity would be extremely valuable in evolutionary currencies. Men need some basis, however, on which to judge a woman’s reproductive capacity.
The solution to this problem is diabolically difficult. Ancestral men had few obvious aids for figuring out which women possessed the highest reproductive value. A woman’s fertility is not stamped on her forehead or advertised with flashing neon signs. It cannot be observed directly, and it is not imbued in her social reputation. Her family is clueless. Even women themselves lack direct knowledge of their reproductive value.
The adaptive problem of detecting which women are fertile comes into clear view when we consider chimpanzees, our closest primate relatives. When a female chimp is fertile, she goes into an estrus phase. Her genitals become engorged, creating bright red swellings that are indeed somewhat like neon signs in their visibility. She emits ovulatory scents at ovulation. These estrus signals send male chimps into a sexual frenzy. To make it even easier on these male chimps, estrus females often energetically solicit sex, “presenting” themselves to males they prefer. Men do not have it this easy. Although there are subtle changes that women undergo when ovulating, such as a slight lightening of their skin and a slight rise in voice pitch, women have nothing approaching the vivid visible ovulation signals emitted by female chimps. Over evolutionary history, vivid signs of human ovulation were largely driven underground, irrevocably changing the ground rules of mating.
A preference nevertheless evolved for fertility. Ancestral men evolved mechanisms to sense cues to a woman’s underlying reproductive value, and two obvious and observable cues were youth and health.4 Old or unhealthy women clearly could not reproduce as much as young, healthy women. Ancestral men solved the problem of finding reproductively valuable women in part by preferring those who were young and healthy. But how can youth and health be discerned?
Youth
It is a fact of fertility that women’s reproductive capacity declines steadily with increasing age after the midtwenties. By the age of forty, a woman’s reproductive capacity is low. By fifty, it is close to zero. Women’s capacity for reproduction is compressed into a fraction of their lives.
Men’s preferences capitalize on this critical cue. In the United States, men uniformly express a desire for mates who are younger than they are. Among college students surveyed from 1939 through 2005 on campuses coast to coast, the preferred age difference hovered around two and a half years.5 Twenty-one-year-old men preferred, on average, women who were eighteen and a half.
Men’s preoccupation with a woman’s youth is not limited to Western cultures. When the anthropologist Napoleon Chagnon was asked which females are most sexually attractive to Yanomamö men of the Amazon, he replied without hesitation, “Females who are moko dude.”6 The word moko, when used with respect to fruit, means that the fruit is harvestable, and when used with respect to a woman, it means that the woman is fertile. Thus, fruit that is moko dude is perfectly ripe, and a woman who is moko dude is postpubescent but has not yet borne her first child, or about fifteen to eighteen years of age. Comparative information on other tribal and traditional peoples suggests that the Yanomamö men are typical in their preference.
Nigerian, Indonesian, Iranian, and Indian men are similarly inclined. Without exception, in every one of the thirty-seven societies examined in the international study, men preferred wives who were younger than themselves. Nigerian men who were twenty-three and a half years old, for example, preferred wives who were six and a half years younger, or just over seventeen years old. Croatian men who were twenty-one and a half years old expressed a desire for wives who were approximately nineteen. Chinese, Canadian, and Colombian men shared with their Nigerian and Croatian brethren a powerful desire for younger women. On average, men from the thirty-seven cultures expressed a desire for wives approximately two and a half years younger than themselves.
Although men universally preferred younger women as wives, the strength of this preference varied somewhat from culture to culture. Scandinavian men in Finland, Sweden, and Norway preferred their brides to be only one or two years younger. Men in Nigeria and Zambia preferred their brides to be six and a half and seven and a half years younger, respectively. In Nigeria and Zambia, which practice polygyny, like many cultures worldwide, men who can afford it are legally permitted to marry more than one woman. Men in polygynous mating systems are typically older than men in monogamous systems by the time they have acquired sufficient resources to attract wives. The larger age difference preferred by Nigerian and Zambian men probably reflects their greater age when they acquire wives.7
This interpretation is supported by a raft of scientific studies showing that, as men get older, they prefer as mates women who are increasingly younger than they are. Consider the statistics derived from online personal advertisements.8 A man’s age has a strong effect on his preferences: men in their thirties prefer women who are roughly five years younger, whereas men in their fifties prefer women ten to twenty years younger.9
Although these findings support the evolutionary hypothesis that men prefer younger, and hence more fertile, women, this perspective actually leads to a very counterintuitive prediction—namely, that young adolescent males should prefer women who are slightly older than they are. Scientific studies bear this prediction out. Adolescent males age fifteen, for example, express a desire for females who are seventeen or eighteen.10 What is fascinating is that this attraction is almost entirely unreciprocated. Women in their late teens do not even notice these young adolescent males, much less find themselves attracted to them. They prefer men a few years older, not a few years younger.
These findings regarding adolescent males contradict two potential alternative explanations for why older men are attracted to younger women. One—an old standby in psychology—is reinforcement theory: that people repeat behaviors for which they are rewarded. Adolescent males are hardly reinforced or rewarded by the women they are most attracted to; indeed, they are ignored or actively shunned by these women. A second explanation is that men are attracted to younger women as a means of exercising power and control. But the mid-adolescent males have no power or control at all over the late-adolescent women they find so beautiful. The fertility explanation, in short, provides the most compelling explanation for the entire pattern of findings, from the attractions of adolescent males to men’s attractions toward women who are increasingly younger relative to their own age as the men get increasingly older.
Actual marriage decisions confirm the preference of men for women who are increasingly younger than they are as they age. American grooms exceed their brides in age by roughly three years at first marriage, five years at second marriage, and eight years at third marriage.11 Men’s preference for younger women also translates into actual marriage decisions worldwide. In Sweden during the 1800s, for example, church documents reveal that men who remarried following a divorce selected new brides 10.6 years younger on average. In all countries around the world where information is available on the ages of brides and grooms, men on average exceed their brides in age.12 Among European countries, the age difference ranges from about two years in Poland to roughly five years in Greece. Averaged across all countries, grooms are three years older than their brides, or roughly the difference expressly desired by men worldwide. In polygynous cultures, the age difference runs even larger. Among the Tiwi of northern Australia, for example, high-status older men often have wives who are two and three decades younger than they are.13 In summary, contemporary men prefer young women because they have inherited from their male ancestors an evolved preference that focused intensely on this cue to a woman’s reproductive value. This psychological preference translates into actual mating decisions much of the time—although as we will see later, people can’t always get what they want.
Standards of Physical Beauty
A preference for youth is merely the most obvious of men’s preferences linked to a woman’s reproductive capacity. Evolutionary logic leads to an even more 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 environments beneficial to our ancestors, so our standards for female beauty embody cues to women’s reproductive capacity.14 Beauty may be in the eyes of the beholder, but those eyes, and the minds behind the eyes, have been shaped by millions of years of human evolution.
Our ancestors had access to two types of observable evidence of a woman’s health and youth: features of physical appearance, such as full lips, clear skin, smooth skin, clear eyes, lustrous hair, and good muscle tone, and features of behavior, such as a bouncy, youthful gait, an animated facial expression, and a high energy level. These physical cues to youth and health, and hence to reproductive capacity, constitute key elements of male standards of female beauty.
Because physical and behavioral cues provide the most powerful observable evidence of a woman’s reproductive value, ancestral men evolved a preference for women who displayed these cues. Men who failed to prefer qualities that signaled high reproductive value—men who preferred to marry gray-haired grandmothers lacking in smooth skin and firm muscle tone—would have left fewer offspring.
Clelland Ford and Frank Beach discovered several universal cues that correspond precisely with this evolutionary theory of beauty.15 Signs of youth, such as clear skin and smooth skin, and signs of health, such as the absence of sores and lesions, are universally regarded as attractive. Any cues to ill health or older age are seen as less attractive. Imagining passionately kissing a lover’s acne is more likely to provoke feelings of disgust than feelings of sexual desire. Poor complexion is always considered a sexual turnoff. Pimples, ringworm, facial disfigurement, and dirtiness are universally seen as unattractive. Clarity and smoothness of skin and freedom from disease are universally attractive.
For example, the anthropologist Bronislaw Malinowski reported that, among the Trobriand Islanders in northwestern Melanesia, “sores, ulcers, and skin eruptions are naturally held to be specially repulsive from the viewpoint of erotic contact.” The “essential conditions” for beauty, in contrast, were “health, strong growth of hair, sound teeth, and smooth skin.”16 Specific features, such as bright eyes and full, well-shaped lips rather than thin or pinched lips, were especially important to the Islanders.
Cues to youth are also paramount in the aesthetics of women’s attractiveness. When men and women rate a series of photographs of women differing in age, judgments of facial attractiveness decline with the increasing age of the woman.17 The ratings of women’s beauty decline regardless of the age or sex of the judge.
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 at least three or four years old. The psychologist Judith Langlois and her colleagues have overturned this conventional wisdom by studying infants’ social responses to faces.18 Adults evaluated color slides of white and black female faces for their attractiveness. Then infants of two to three months of age and six to eight months of age were shown pairs of these faces that differed in their degree of attractiveness to adults. Both younger and older infants looked longer at the more attractive faces, suggesting that standards of beauty apparently emerge quite early in life. In a second study, Langlois found that twelve-month-old infants showed more observable pleasure, more play involvement, less distress, and less withdrawal when interacting with strangers who wore attractive masks than when interacting with strangers who wore unattractive masks.19 In a third study, Langlois found that twelve-month-old infants played significantly longer with attractive dolls than with unattractive dolls. No training seems necessary for these standards to emerge. This evidence challenges the common view that the idea of attractiveness is learned through gradual exposure to current cultural standards.
Many, but not all, constituents of beauty are neither arbitrary nor culturally capricious. When the psychologist Michael Cunningham asked people of different races to judge the facial attractiveness of photographs of women of various races, he found great consensus about who was and was not good-looking.20 Asian and American men, for example, agree with each other on which Asian and American women are most and least attractive. Consensus has also been found among Chinese, Indian, and English samples, between South Africans and Americans, and between black and white Americans.21
Photographic manipulation provides evidence supporting evolutionary theories of female beauty. To find out what makes for an attractive face, Langlois and her team generated composites of the human face by means of computer graphics technology. These faces were then superimposed upon each other to create new faces. The new composite faces were made up of a differing number of individual faces—four, eight, sixteen, or thirty-two. People then rated the attractiveness of each composite face, as well as the attractiveness of each individual face that made up the composite. Results proved startling. The composite faces were uniformly judged to be more physically attractive than any of the individual ones. The sixteen-face composite was deemed more attractive than the four-face or eight-face composites, and the thirty-two-face composite was deemed the most attractive of all. Because superimposing individual faces tends to eliminate their irregularities and make them more symmetrical, the average or symmetrical composite faces were more attractive than actual individual faces.22
One explanation for why symmetrical faces are considered more attractive comes from research conducted by the psychologist Steve Gangestad and the biologist Randy Thornhill, who examined the relationship between facial and bodily asymmetries and judgments of attractiveness.23 Repeated environmentally induced injuries and diseases produce asymmetries during development. These include not just injuries and other physical insults, which may provide a cue to health, but also the parasites that inhabit the human body and the mutations that inhabit the human genome. Because parasites and genetic mutations cause physical asymmetries, the degree of asymmetry can be used as a cue to the health status of the individual and as an index of the degree to which the individual’s development has been perturbed by various stressors. In scorpionflies and swallows, for example, males prefer to mate with symmetrical females and tend to avoid those that show asymmetries. In humans as well, when Gangestad and Thornhill measured people’s features, such as foot breadth, hand breadth, ear length, and ear breadth, and independently had these people evaluated on attractiveness, they found that less symmetrical people were seen as less attractive. Human asymmetries also increase with age. Older people’s faces are far more asymmetrical than younger people’s faces, so that symmetry provides another cue to youth as well. This evidence provides yet another confirmation of the theory that cues to health and cues to youth are embodied in standards of attractiveness—standards that emerge remarkably early in life.
Body Shape
Facial beauty is only part of the picture. Features of the rest of the body provide abundant cues to a woman’s reproductive capacity. Standards for bodily beauty vary somewhat from culture to culture, along such dimensions as a plump versus slim body build or light versus dark skin. Emphasis on particular physical features, such as eyes, ears, buttocks, or genitals, also varies by culture. Some cultures, such as the Nama, a branch of Hottentots residing in southwest Africa, consider an elongated labia majora to be sexually attractive, and they work at pulling and manipulating the vulvar lips to enhance attractiveness. Men in many cultures prefer large, firm breasts, but in a few, such as the Azande of eastern Sudan and the Ganda of Uganda, men are reported to view long, pendulous breasts as the more attractive.24
The most culturally variable standard of beauty seems to be in the preference for a slim versus plump body build. This variation is linked partly with the social status that body build conveys. In cultures where food is scarce, such as among the Bushmen of Australia, plumpness signals wealth, health, and adequate nutrition during development.25 In cultures where food is relatively abundant, such as the United States and many western European countries, the relationship between plumpness and status is reversed and the rich signal their status through relative thinness.26 Men apparently do not have an evolved preference for a particular amount of body fat per se. Rather, they have an evolved preference for whatever features are linked with status, which vary in predictable ways from culture to culture. Clearly such a preference does not require conscious calculation or awareness.
Studies by the psychologist Paul Rozin and his colleagues have revealed a disturbing aspect of women’s and men’s perceptions of the desirability of plump versus thin body types.27 American men and women viewed nine female figures that varied from very thin to very plump. The women were asked to indicate their ideal for themselves, as well as their perception of men’s ideal for the female figure. In both cases, women selected a figure slimmer than average. When men were asked to select which female figure they preferred, however, they selected the figure of average body size. American women erroneously believe that men desire thinner women than they actually do prefer. These findings refute the belief that men desire women who are runway-model thin; most men do not.
While men’s preferences for a particular body size vary, one preference for body shape that is fairly invariant, the psychologist Devendra Singh discovered, is the preference for a small waist size relative to hip size.28 Before puberty, boys and girls show a similar fat distribution. At puberty, however, a dramatic change occurs. Boys lose fat from their buttocks and thighs, while the release of estrogens in pubertal girls causes them to deposit fat in their lower trunk, primarily on their hips and upper thighs. Indeed, the volume of body fat in this region is 40 percent greater for women than for men.
In other words, the waist-to-hip ratio is similar for the sexes before puberty, but after puberty women’s hip fat deposits cause their waist-to-hip ratio to become significantly lower than men’s. Healthy, reproductively capable women have a waist-to-hip ratio between 0.67 and 0.80, while healthy men have a ratio in the range of 0.85 to 0.95. Abundant evidence now shows that the waist-to-hip ratio is an accurate indicator of women’s reproductive status. Women with a lower ratio show earlier pubertal endocrine activity. Women with a higher ratio have more difficulty becoming pregnant, and those who do become pregnant do so at a later age than women with a lower ratio. The waist-to-hip ratio is also an accurate indication of long-term health status. Diseases such as diabetes, hypertension, heart problems, previous stroke, and gallbladder disorders are linked with the distribution of fat, as reflected by the ratio. The link between the waist-to-hip ratio and both health and reproductive status made it a reliable cue for ancestral men’s preferences in a mate.
Singh discovered that waist-to-hip ratio is indeed a powerful cue to women’s attractiveness. In a dozen studies conducted by Singh, men rated the attractiveness of female figures, which varied in both their waist-to-hip ratio and their total amount of fat. Men find the average figure to be more attractive than a thin or fat figure. Regardless of the total amount of fat, however, men find women with a low waist-to-hip ratio to be the most attractive. Women with a ratio 0.70 are more attractive than women with a ratio of 0.80, who in turn are more attractive than women with a ratio of 0.90. Finally, Singh’s analysis of Playboy centerfolds and winners of beauty contests in the United States over thirty consecutive years confirmed the invariance of this cue. Although both centerfolds and beauty contest winners got thinner, their waist-to-hip ratio remained roughly the same at around 0.70.
There is one more possible reason for the importance of waist-to-hip ratio. Pregnancy alters this ratio dramatically. A higher ratio mimics pregnancy and therefore may render women less attractive as mates or sexual partners. A lower ratio, in turn, signals health, reproductive capacity, and lack of current pregnancy. Men’s standards of female attractiveness have evolved over thousands of generations to detect and find attractive this reliable cue.
The Importance of Physical Appearance
Because of the bounty of fertility cues conveyed by a woman’s physical appearance, and because male standards of beauty have evolved to correspond to these cues, men have evolved to prioritize appearance and attractiveness in their mate preferences. In the United States mate preferences for physical attractiveness, physical appearance, good looks, or beauty have been lavishly documented. When 5,000 college students were asked in the 1950s to identify the characteristics they wanted in a future husband or wife, men listed physical attractiveness far more often than women did.29 The sheer number of terms that men listed betrayed their values. They wanted a wife who was pretty, attractive, beautiful, gorgeous, comely, lovely, ravishing, and glamorous. American college women, at that time at least, rarely listed physical appearance as paramount in their ideal husband.
Multi-decade mating studies in the United States from 1939 to 1996 found that men rate physical attractiveness and good looks as more important and desirable in a potential mate than do women.30 Men tend to see attractiveness as important, whereas women tend to see it as desirable but not very important. The gender difference in the importance of attractiveness remains constant from one generation to the next. Its size does not vary throughout the decades. Men’s greater preference for physically attractive mates is among the most consistently documented psychological sex differences.31
This does not mean that the importance people place on attractiveness is forever fixed. On the contrary, the importance of attractiveness increased dramatically in the United States in the twentieth century.32 For nearly every decade since 1930, physical appearance grew in importance for men and women about equally, corresponding with the rise in television, fashion magazines, advertising, and other media depictions of attractive models. For example, the importance attached to good looks in a marriage partner on a scale of 0.00 to 3.00 increased between 1939 and 1989 from 1.50 to 2.11 for men and from 0.94 to 1.67 for women. Similar shifts have been observed in China, India, and Brazil well into the twenty-first century.33 These shifts show that mate preferences can change. But the sex difference so far remains invariant. The gap between men and women has been constant since the late 1930s in all countries studied thus far.
These sex differences are not limited to the United States or to Western cultures. Regardless of the location, habitat, marriage system, or cultural living arrangement, men in all thirty-seven cultures included in the international study on choosing a mate valued physical appearance in a potential mate more than women did. China typified the average difference in importance attached to beauty: Chinese men gave it a 2.06 and women gave it a 1.59. This internationally consistent sex difference persists despite variations in ranking, in wording, and in race, ethnicity, religion, hemisphere, political system, and mating system. Among the Hadza, more than five times as many men as women placed great importance on fertility in a spouse.34 When asked how they could tell that a woman could have many children, most Hadza men responded by saying, “You can tell just by looking,” suggesting their awareness that appearance conveys vital information about fertility. Men’s preference for physically attractive mates is a species-wide psychological mechanism that transcends culture. Women too value appearance in a mate, as they should because appearance conveys health for both sexes, but they do not prioritize it as much as men.
Men’s Status and Women’s Beauty
Men value a woman’s attractiveness for reasons other than her reproductive value. The consequences of women’s attractiveness for a man’s social status are critical. Everyday folklore tells us that our mate is a reflection of ourselves. Men are particularly concerned about status, reputation, and hierarchies because elevated rank has always been an important means of acquiring the resources that make men attractive to women. It is reasonable, therefore, to expect that a man will be concerned about the effect that his mate has on his social status—an effect that has consequences for gaining additional resources and mating opportunities.
A person’s status and resource holdings, however, often cannot be observed directly. They must instead be inferred from tangible characteristics. Among humans, one set of cues is people’s ornamentation. Gold chains, expensive artwork, or fancy cars may signal to both sexes an abundance of resources that could be directed toward parental investment.35 Men seek attractive women as mates not simply for their reproductive value but also as signals of status to same-sex competitors and to other potential mates.36
Experiments have documented the influence of attractive mates on men’s social status. When shown photographs of unattractive men paired with attractive spouses, people attribute status and professional prestige to those men more than in other pairings, such as attractive men with unattractive women, unattractive women with unattractive men, and even attractive men with attractive women. People suspect that an unattractive man must have high status if he can interest a stunning woman, presumably because people know that attractive women have high mate value and usually can get what they want.
In my study of human prestige criteria, dating someone who is physically attractive greatly increases a man’s status, whereas it increases a woman’s status only somewhat.37 In contrast, a man who dates an unattractive woman experiences a moderate decrease in status, whereas a woman who dates an unattractive man experiences only a trivial decrease in status.
These trends occur across cultures. When my research collaborators and I surveyed native residents of China, Poland, Guam, Romania, Russia, and Germany in parallel studies of human prestige criteria, we found that in each of these countries, acquiring a physically attractive mate enhances a man’s status more than a woman’s. In each country, having an unattractive mate hurts a man’s status more than it does a woman’s. Men across cultures today value attractive women not only because attractiveness signals a woman’s reproductive capacity but also because it signals status, and status, in turn, creates more mating opportunities.
Sexual Orientation and Mate Preferences
The premium that men place on a mate’s appearance is not limited to heterosexuals. Some scientists contend that same-sex relationships provide an acid test for the evolutionary basis of sex differences in the desires for a mate.38 Do gay men show preferences more or less like those of other men, differing only in the sex of the person they desire? Do they show preferences similar to those of women? Or do they have unique preferences unlike the typical preferences of either sex?
No one knows the exact percentage of homosexuals in any culture, past or present. Part of the difficulty lies with definitions. The sexologist Alfred Kinsey estimated that more than one-third of all men engage at some point in life in some form of homosexual activity, typically as part of adolescent experimentation. Far fewer people, however, express a strong preference for the same sex as a mate. Most estimates put the figure at about 3 to 4 percent for men and 1 to 2 percent for women.39 The discrepancy between the percentages of people who have engaged in some kinds of homosexual acts and people who express a core preference for partners of the same sex suggests an important distinction between the underlying psychology of preference and the outward manifestation of behavior. Some men who prefer women as mates may nonetheless substitute a man as a sex partner, because of either circumstance or opportunity.
No one knows why some people have a strong preference for members of their own sex as mates, although this lack of knowledge has not held back speculation. One suggestion is the so-called kin selection theory of homosexuality, which holds that homosexuality evolved when some people served better as aides to their close genetic relatives than as reproducers.40 No current evidence exists to support this theory. Gay men do not invest more in their nephews and nieces than do heterosexual men. Other theories point to the mother’s intrauterine environment, birth order, and other nongenetic causes. If there exists one single large cause of sexual orientation, it is likely that scientists would know it by now. That the origins of homosexuality remain somewhat of a mystery suggests that the causes of sexual orientation are likely to be multiple and complex.
Homosexual preferences in a mate, in contrast, are far less mysterious. Studies document the great importance that homosexual men place on the youth and physical appearance of their partners. William Jankowiak and his colleagues asked homosexual and heterosexual individuals, both men and women, to rank sets of photographs of men and women differing in age on physical attractiveness.41 Gay and heterosexual men alike ranked the younger individuals as consistently more attractive. Neither lesbian nor heterosexual women, in contrast, placed any importance on youth in their ranking of attractiveness. These results suggest that lesbian women are very much like heterosexual women in their mate preferences, except with respect to the sex of the person they desire, and that homosexual men are similar to heterosexual men in their mate preferences.
The psychologists Kay Deaux and Randel Hanna conducted a systematic study of homosexual mate preferences.42 They collected 800 ads from several East Coast and West Coast newspapers, equally sampling male heterosexuals, female heterosexuals, gay men, and lesbians. Using a coding scheme, they calculated the frequency with which members of each of these groups offered and sought particular characteristics, such as physical attractiveness, financial security, and personality traits.
Lesbians tended to be similar to heterosexual women in placing little emphasis on physical appearance, with only 19.5 percent of the heterosexual women and 18 percent of the lesbians mentioning this quality. In contrast, 48 percent of heterosexual men and 29 percent of gay men stated that they were seeking attractive partners. Among all groups, lesbians listed their own physical attractiveness less often than any other group; such mentions appeared in only 30 percent of their ads. Heterosexual women, in contrast, offered attractiveness in 69.5 percent of the ads, gay men in 53.5 percent, and heterosexual men in 42.5 percent. Only 16 percent of the lesbians requested a photograph of respondents to their ads, whereas 35 percent of heterosexual women, 34.5 percent of gay men, and 37 percent of heterosexual men made this request.
Lesbian women are distinct from the other three groups in specifying fewer physical characteristics, such as weight, height, eye color, or body build. Whereas only 7 percent of lesbians mentioned their desire for specific physical attributes, 20 percent of heterosexual women, 38 percent of gay men, and 33.5 percent of heterosexual men requested particular physical traits. And as with overall attractiveness, lesbians stood out in that only 41.5 percent listed physical attributes among the assets they offered, whereas 64 percent of heterosexual women, 74 percent of gay men, and 71.5 percent of heterosexual men offered particular physical assets. It is clear that gay men are similar to heterosexual men in the premium they place on appearance. Lesbian women are more like heterosexual women in their desires, but differ in placing less value on physical qualities, both in their offerings and in the qualities they seek.
Less formal studies confirm the centrality of youth and physical appearance for male homosexuals. Surveys of the gay mating market consistently find that physical attractiveness is the key determinant of the desirability of a potential partner. Male homosexuals place great emphasis on dress, grooming, and physical condition. And youth is a key ingredient in judging attractiveness: “Age is the monster figure of the gay world.”43
The sociologists Philip Blumstein and Pepper Schwartz found that the physical beauty of a partner was critical to the desires of homosexual and heterosexual men more than to lesbian or heterosexual women, even among already coupled individuals.44 They found that 57 percent of gay men and 59 percent of heterosexual men felt that it was important that their partner be sexy-looking. In contrast, only 31 percent of the heterosexual women and 35 percent of the lesbian women stated that sexy looks were important in a partner. Male homosexuals and male heterosexuals seem to have similar mate preferences, except with respect to the sex of their preferred partner. Both place a premium on appearance, and youth and youthful features are central ingredients in their definition of beauty.
Men Who Achieve Their Desires
Although most men place a premium on youth and beauty, it is clear that not all men succeed in satisfying their desires. Men who lack the status and resources that women want, for example, generally have the most difficult time attracting good-looking young women and must settle for less than their ideal. Evidence comes from men who have historically been in a position to get exactly what they prefer, such as kings, emperors, despots, and other men of unusually high status. In the 1700s and 1800s, for example, wealthier men from the Krummerhörn population of Germany married younger brides than did men lacking wealth. Similarly, high-status men, from the Norwegian farmers of 1700 to 1900 to the Kipsigis in contemporary Kenya, have consistently secured younger brides than their lower-status counterparts.45
Kings and despots routinely stocked their harems with young, attractive, nubile women and had sex with them frequently. The Moroccan emperor Moulay Ismail the Bloodthirsty, for example, acknowledged having sired 888 children. His harem had 500 women. When each woman reached the age of thirty, she was banished from the emperor’s harem, sent to a lower-level leader’s harem, and replaced by a younger woman. Roman, Babylonian, Egyptian, Incan, Indian, and Chinese emperors all shared the tastes of Emperor Ismail and instructed their trustees to scour the land for as many young pretty women as they could find.46
Marriage patterns in modern America confirm the fact that the men with the most resources are the best equipped to actualize their preferences. High-status men, such as the aging rock stars Rod Stewart and Mick Jagger and the movie stars George Clooney and Johnny Depp, frequently select women decades younger. One study examined the impact of a man’s occupational status on the woman he marries. Men who are high in occupational status are able to marry women who are considerably more physically attractive than are men who are low in occupational status.47 Indeed, a man’s occupational status seems to be the best predictor of the attractiveness of the woman he marries. Men in a position to attract younger women often do.
Men who enjoy high status and income are apparently aware of their ability to attract women of higher value. In a study of a computer dating service involving 1,048 German men and 1,590 German women, the ethologist Karl Grammer found that as men’s income goes up, they seek younger partners.48 Each increment in income is accompanied by a decrease in the age of the woman sought.
Not all men, however, have the status, position, or resources to attract young women, and some men end up mating with older women. Many factors determine the age of the woman at marriage, including the woman’s preferences, the man’s own age, the man’s mating assets, the strength of the man’s other mate preferences, and the woman’s appearance. Mate preferences are not invariably translated into actual mating decisions for all people all of the time, just as food preferences are not invariably translated into actual eating decisions for all people all of the time. But men who are in a position to get what they want often partner up with young, attractive women. Ancestral men who actualized these preferences experienced greater reproductive success than those who did not.
Media Effects on Standards
Advertisers exploit the universal appeal of beautiful, youthful women. Some argue that the media and Madison Avenue construct a single, arbitrary standard of beauty that everyone must live up to.49 Advertisements are thought to convey unnatural, photoshopped images of beauty and to tell people to strive to embody those images. This interpretation may be partially true, particularly when it comes to depicting unnaturally thin female models, but it is also at least partially false. Standards of beauty are not arbitrary but rather embody reliable cues to reproductive value. Advertisers have no special interest in inculcating a particular set of beauty standards; they do want to use whatever sells products. Advertisers perch a clear-skinned, regular-featured young woman on the hood of the latest-model car, or gather several attractive young women to stare fondly at a man drinking a brand-name beer, because these images exploit men’s evolved psychological mechanisms and therefore sell cars and beer, not because advertisers want to promulgate a single standard of beauty.
The media images with which we are bombarded daily, however, have a potentially damaging consequence. In one study, after groups of men looked at photographs of either highly attractive women or women of average attractiveness, they evaluated their commitment to their current romantic partner.50 The men who had viewed pictures of attractive women thereafter judged their actual partner to be less attractive than did the men who had viewed analogous pictures of women who were average in attractiveness. Perhaps more important, the men who had viewed attractive women thereafter rated themselves as less committed to, less satisfied with, less serious about, and less close to their actual partners. Parallel results were obtained in another study in which men viewed physically attractive nude centerfolds—they rated themselves as less attracted to their partners.51
The reason for these changes is found in the unrealistic nature of the images. The few attractive women selected for advertisements are chosen from thousands of applicants. In many cases, literally thousands of pictures are taken of a chosen woman. Playboy, for example, was reputed to shoot roughly 6,000 pictures for its centerfold each month. From thousands of pictures, a few are selected for advertisements and centerfolds. And then those images are photoshopped. So what men see are the most attractive women in their most attractive poses with the most attractive background in the most attractive photoshopped images. Contrast these photographs with what ancestral man would have witnessed, living in a band of no more than 150 individuals. It is doubtful that he would see hundreds or even dozens of attractive women in that environment. If there were plenty of attractive fertile women, however, he might reasonably consider switching mates and decreasing his commitment to his existing mate.
We carry with us the same evaluative mechanisms that evolved in ancient times. Now, however, these psychological adaptations are artificially stimulated by the dozens of attractive women whose images men witness daily in our visually saturated culture on the Internet, in magazines, on billboards, on television, and in movies. These images do not represent real women in our actual social environment. Rather, they hijack adaptations designed for a different mating environment. They sometimes create unhappiness by interfering with existing real-life relationships. The ability to scroll through thousands of potential mates on Internet dating sites and apps such as Tinder, Match.com, and OKCupid may trick our psychology of mating into thinking that there is always someone better out there if only we can swipe or click through enough options.
As a consequence of viewing these images, men become dissatisfied and less committed to their mates. The potential damage inflicted by these images affects women as well, because they create a spiraling and unhealthy competition among women to embody the images they see daily—images of women who presumably are desired by men, but in actuality are much thinner than most men really find attractive. The unprecedented rates of eating disorders, such as anorexia nervosa, and cosmetic surgery, such as tummy tucks and breast enlargement, may stem in part from these media images; some women go to extreme lengths to fulfill what they perceive to be men’s desires. But the images do not cause this unfortunate result by creating standards of beauty that were previously absent. Rather, they work by exploiting men’s existing evolved standards of beauty and women’s competitive mating mechanisms on an unprecedented and unhealthy scale.
Facial and bodily beauty, as important as they are in men’s mating preferences, solve for men only one set of adaptive problems—identifying and becoming sexually aroused by women who show signs of fertility. Selecting a reproductively valuable woman, however, provides no guarantee that her value will be monopolized exclusively by one man. The next critical adaptive problem is to ensure paternity.
Chastity and Fidelity
Mammalian females typically enter estrus only at intervals. Vivid visual cues and strong scents often accompany estrus and powerfully attract males. Sexual intercourse occurs primarily in this narrow envelope of time. Women, however, do not send any sort of genital signal when they ovulate. Nor is there much evidence that women secrete detectable olfactory cues. Indeed, women are rare among primates in possessing the unusual adaptation of comparatively concealed or cryptic ovulation.52 Yes, there are some subtle changes—a slight lightening of the skin, a slightly more attractive voice pitch, and even a higher sexual drive. But relatively cryptic ovulation obscures a woman’s reproductive status.
Concealed ovulation dramatically changed the ground rules of human mating. Women became attractive to men not just when ovulating but throughout their menstrual cycles. Cryptic ovulation created a special adaptive problem for men by decreasing the certainty of their paternity. Consider a primate male who monopolizes a female for the brief period that she is in estrus. In contrast to human males, he can be fairly “certain” of his paternity, although obviously not consciously. The period during which he must guard the female and have sex with her is sharply constrained. Before and after her estrus, he can go about his other business without running the risk of cuckoldry.
Ancestral men did not have this luxury. Our human ancestors never knew when a woman was ovulating. Because mating is not the sole activity that humans require to survive and reproduce, women could not be guarded around the clock. And the more time a man spent guarding, the less time he had available for grappling with other critical adaptive challenges. Ancestral men therefore were faced with a unique paternity problem not faced by other primate males—how to be certain of their paternity when ovulation was concealed.
Marriage or long-term committed mating provided one solution.53 Men who married would benefit reproductively relative to other men by substantially increasing their probability of paternity. Repeated sexual intercourse with one woman throughout her ovulation cycle raised a man’s odds that she would bear his child. The social traditions of marriage function as public ties that bind a couple, with fidelity enforced by family members as well as by each partner. Marriage also provides men with opportunities to learn intimately about their mate’s personality and subtle patterns of behavior, making it difficult for her to hide signs of infidelity. These benefits of marriage would have outweighed the costs of forgoing the sexual opportunities sometimes available to ancestral bachelors, at least under some conditions.
For an ancestral man to reap the reproductive benefits of marriage, he had to seek reasonable assurances that his mate would indeed remain sexually faithful to him. Men who failed to be aware of these cues would have lost out in the currency of relative reproductive success. Failure to be sensitive to these cues so as to ensure their partner’s fidelity would have diverted years of her parental investment to another man’s children. Men who were indifferent to the potential sexual contact between their wives and other men would not have been successful in the game of differential reproductive success.
Our male forebears solved this uniquely male adaptive problem by seeking qualities in a potential mate that might increase the odds of securing their paternity. At least two preferences in a mate could solve the problem for males: the desire for premarital chastity and the quest for postmarital sexual loyalty. Before the use of modern contraceptives, chastity provided a cue to the future certainty of paternity. On the assumption that a woman’s proclivities toward chaste behavior would be stable over time, her premarital chastity signaled her likely future fidelity.
In the modern United States, men value virgin brides modestly more than women value virgin grooms. But the value they place on it has declined over the past seventy years, coinciding with the increasing availability of reliable birth control methods.54 In the 1930s, men viewed chastity as close to indispensable, but in the past few decades men have rated it as desirable but not crucial. Among the eighteen characteristics rated, chastity declined from the tenth most valued in 1939 to the seventeenth most valued in the late 1980s and 1990s and into the 2000s and 2010s. Furthermore, American men differ regionally in how they value chastity. College students in Texas, for example, desire a chaste mate more than college students in California, rating it a 1.13 as opposed to 0.73 on a 3.00 scale. Despite the decline in the value of virginity in the twentieth century and despite regional variations, the sex difference remains—men more than women emphasize chastity in a potential committed mateship.
The trend for men to value chastity more than women holds up worldwide, but cultures vary tremendously in the value placed on chastity. At one extreme, people in China, India, Indonesia, Iran, Taiwan, and the Palestinian areas of Israel attach a high value to chastity in a potential mate. At the opposite extreme, people in Sweden, Norway, Finland, the Netherlands, Germany, and France believe that virginity is largely irrelevant or unimportant in a potential mate.
In contrast to the worldwide consistency in the different preferences by gender for youth and physical attractiveness, only 62 percent of the cultures in the international study placed a significantly different value on chastity in a committed mateship by sex. Where sex differences in the value of virginity were found, however, men invariably placed a greater value on it than women did. In no culture did women desire chastity more than men did.
The cultural variability in the preference of each sex for chastity is explained by several factors, including the prevailing incidence of premarital sex, the degree to which chastity can be demanded in a mate, the economic independence of women, and the reliability with which chastity can be evaluated. Chastity differs from other attributes, such as a woman’s physical attractiveness, in that it is less directly observable. Even physical tests of female virginity are unreliable, whether from variations in the structure of the hymen, rupture due to nonsexual causes, or deliberate alteration.55
Variation in the value that people place on chastity may be traceable in part to variability in the economic independence of women and in women’s control of their own sexuality. In some cultures, such as Sweden, premarital sex is not discouraged and practically no one is a virgin at marriage. One reason may be that women in Sweden are far less economically reliant on men than women in most other cultures. The legal scholar Richard Posner notes that marriage provides few benefits for Swedish women relative to women in most other cultures.56 The Swedish social welfare system includes day care for children, long paid maternity leaves, and many other material benefits. The Swedish taxpayers effectively provide women with what partners otherwise would or might. Women’s economic independence from men lowers the cost to them of a free and active sex life before marriage, or as an alternative to marriage. Thus, practically no Swedish women are virgins at marriage, and hence the value that Swedish men place on chastity has declined to a worldwide low of 0.25.57
Differences in the economic independence of women, in the benefits provided by husbands, and in the intensity of competition for husbands all drive the critical cultural variation.58 Where women benefit from marriage and where competition for husbands is fierce, women compete to signal chastity, causing the average amount of premarital sex to go down. Where women control their economic fate, do not require so much of men’s investment, and need to compete less for reliable providers, they are freer to disregard men’s preferences, which causes the average amount of premarital sex to go up. Men everywhere might value chastity in a long-term mate if they could get it, but in many cultures they simply cannot demand it of their brides.
From a man’s reproductive perspective, a more important cue to the certainty of paternity than virginity per se is the assurance of future fidelity. If men cannot reasonably require virginity, they can choose mates for sexual loyalty or fidelity. In fact, the study of short-term and long-term mating found that American men viewed having little sexual experience as desirable in a spouse. Furthermore, men saw promiscuity as especially undesirable in a permanent mate, rating it –2.07 on a scale of –3.00 to +3.00. The actual amount of prior sexual activity in a potential mate, rather than virginity per se, would have provided an excellent guide for ancestral men who sought to solve the problem of uncertainty of paternity. Indeed, the single best predictor of extramarital sex is premarital sexual permissiveness—people who have many sex partners before marriage tend to be more unfaithful than those who have few sex partners before marriage.59
Modern men place a premium on fidelity. When American men in the study of short-term and long-term partners evaluated sixty-seven possible characteristics for their desirability in a committed mateship, faithfulness and sexual loyalty emerged as the most highly valued traits.60 All men give these traits the highest rating possible, an average of +2.85 on a scale of –3.00 to +3.00. Men regard unfaithfulness as the least desirable characteristic in a wife, rating it a –2.93, reflecting the high value that men place on fidelity. Men abhor promiscuity and infidelity in their wives. Unfaithfulness proves to be more upsetting to men than any other pain a spouse can inflict on her mate. Women also become extremely upset over an unfaithful mate, but several other factors, such as sexual aggressiveness, exceed infidelity in the grief they cause women.61
The sexual revolution of the 1960s and 1970s, with its promises of sexual freedom and lack of possessiveness, apparently has had a limited impact on men’s preferences for sexual fidelity. Nor has the overhyped hookup culture on college campuses today significantly changed these preferences. Cues to fidelity still signal that the woman is willing to channel all of her reproductive value exclusively to her husband. A woman’s future sexual conduct looms large in men’s commitment decisions. The fact that nonpaternity rates—that is, the prevalence of children in a marriage mistakenly believed to have been fathered by the husband—tend to be quite low in most cultures, many as low as 1 to 3 percent, suggests that most men who commit to marriage have largely succeeded in solving this key adaptive problem.62
Evolutionary Bases of Men’s Desires
The great emphasis that men place on a woman’s physical appearance is not some immutable biological law of the animal world. Indeed, in many other species, such as the peacock, it is the females who place the greater value on physical appearance. Nor is men’s preference for youth a biological universal in the animal world. Some primate males, such as orangutans, chimpanzees, and Japanese macaques, prefer older females, who have already demonstrated their reproductive abilities by giving birth; they show low sexual interest in adolescent females because they have low fertility.63 But human males have faced a unique set of adaptive problems and so have evolved a unique sexual psychology. They prefer youth because of the centrality of marriage in human mating. Their desires are designed to gauge a woman’s future reproductive potential, not just the chance of immediate impregnation. They place a premium on physical appearance because of the wealth of reliable cues it provides to the reproductive potential of a potential mate.
Men worldwide want physically attractive, young, and sexually loyal wives who will remain faithful to them over the long run. These preferences cannot be attributed to Western culture, to capitalism, to white Anglo-Saxon bigotry, to the media, or to incessant brainwashing by advertisers. They are universal across cultures and are absent in none. They are deeply ingrained psychological adaptations that drive our mating decisions, just as our evolved taste preferences drive our decisions on food consumption.
Homosexual mate preferences, ironically, provide a testament to the depth of these evolved psychological mechanisms. The fact that physical appearance figures centrally in gay men’s mate preferences, and that youth is a key ingredient in their standards of beauty, suggests that not even variations in sexual orientation alter these fundamental male adaptations.
These preferences upset some people because they are unfair. We can modify our physical attractiveness only in limited ways, and some people are born, or develop into, better-looking individuals than others. Beauty is not distributed democratically. A woman cannot alter her age, and a woman’s reproductive value declines more sharply with age than a man’s; evolution has dealt women a cruel hand, at least in this regard. (Later we will see how evolution has dealt men a cruel hand in causing their earlier death.) Women fight the decline through cosmetics, through plastic surgery, through fitness classes. An $8 billion cosmetics industry has emerged in America to exploit these trends.
After a lecture on the subject of sex differences in mate preferences, one woman suggested that I suppress the findings because of the distress they would cause women. Women already have it hard enough in this male-dominated world, she felt, without having scientists tell them that their mating problems may be based in men’s evolved psychology. Yet suppression of this truth is unlikely to help, just as concealing the fact that people have evolved preferences for succulent, ripe fruit is unlikely to change their preferences. Railing against men for the importance they place on beauty, youth, and fidelity is like railing against meat eaters because they prefer animal protein. Telling men not to become aroused by signs of youth and health is like telling them not to experience sugar on their tongues as sweet.
Many people hold an idealistic view that standards of beauty are arbitrary, that beauty is only skin-deep, that cultures differ dramatically in the importance they place on appearance, and that Western standards stem from the media, parents, the culture, or other agents of socialization. But standards of attractiveness are not arbitrary—they reflect cues to youth and health, and hence to reproductive value. Beauty is not merely skin-deep. It reflects internal reproductive capabilities. Although modern fertility technology grants women greater latitude for reproducing across a wider age span, men’s preferences for women who show apparent signs of reproductive capacity continue to operate today in spite of the fact that they were designed in an ancestral world that may no longer exist.
Cultural conditions, economic circumstances, and technological inventions, however, play a critical role in men’s evaluation of the importance of chastity. Where women are less economically dependent on men, as in Sweden, sexuality is highly permissive, and men do not desire or demand chastity from potential wives. These shifts highlight the sensitivity of some mate preferences to features of culture and context.
Despite cultural variations, sexual fidelity tops the list of men’s long-term mate preferences. Although many men in Western culture cannot require virginity, they usually insist on sexual loyalty. Birth control technology may have rendered this mate preference unnecessary for its original function of ensuring paternity, but the mate preference nevertheless persists. A man does not relax his desire for fidelity in his wife just because she takes birth control pills. This constant demonstrates the importance of our evolved sexual psychology—a psychology that was designed to deal with critical cues from an ancestral world but that continues to operate with tremendous force in today’s modern world of mating.
That world of mating, however, involves more than marriage. If ancestral couples had always remained faithful, there would have been no selection pressure for the intense concern with fidelity. The existence of this concern means that both sexes must also have engaged in casual sex and sometimes infidelity. So we must turn now to this mysterious region of human sexuality.