New research reveals modern-day mating strategies are firmly based in Stone Age psychology
By William F. Allman (San Francisco Chronicle THIS WORLD section, July 25, 1993, p. 8-10)

It’s a dance as old as the human race. At cocktail lounges and church socials, during office coffee breaks and dinner parties—and most blatantly, perhaps, in the personal ads in newspapers and magazines—men and women perform the elaborate ritual of advertisement and assessment that precedes an essential part of nearly every life: mating. More than 90 percent of the world’s people marry at some point in their lives, and it is estimated that a similarly large number of people engage in affairs, liaisons, flings or one-night stands. The who, what, when and where of love, sex and romance are a cultural obsession that is reflected in everything from Shakespeare to soap operas and from Tristan and Isolde to 2 Live Crew, fueling archetypes like the coy ingenue, the rakish cad, the trophy bride, Mrs. Robinson, Casanova and lovers both star-crossed and blessed.

It all may seem very modern, but a new group of researchers argues that love, American style, is in fact part of a universal human behavior with roots stretching back to the dawn of humankind. These scientists contend that, in stark contrast to the old image of brute cavemen dragging their mates by the hair to their dens, our ancient ancestors—men and women alike—engaged in a sophisticated mating dance of sexual intrigue, shrewd strategizing and savvy negotiating that has left its stamp on human psychology. People may live in a thoroughly modern world, these researchers say, but within the human skull is a Stone Age mind that was shaped by the mating concerns of our ancient ancestors and continues to have a profound influence on behavior today. Indeed, this ancient psychological legacy influences everything from sexual attraction to infidelity and jealousy—and, as remarkable new research reveals, even extends its reach all the way down to the microscopic level of egg and sperm.

These new researchers call themselves evolutionary psychologists. In a host of recent scientific papers and at a major conference in June at the London School of Economics, they argue that the key to understanding modern sexual behavior lies not solely in culture, as some anthropologists contend, nor purely in the genes, as some socio-biologists believe. Rather, they say, understanding human nature is possible only if scientists begin to understand the evolution of the human mind. Just as humans have evolved specialized biological organs to deal with the intricacies of sex, they say, the mind, too, has evolved customized mental mechanisms for coping with this most fundamental aspect of human existence.

When it comes to sexuality and mating, evolutionary psychologists say, men and women often are as different psychologically as they are physically. Scientists have long known that people typically choose mates who closely resemble themselves in terms of weight, height, intelligence and even earlobe length. But a survey of more than 10,000 people in 37 cultures on six continents, conducted by University of Michigan psychologist David Buss, reveals that men consistently value physical attractiveness and youth in a mate more than women do; women. equally as consistently are more concerned than men with a prospective mate’s ambition, status and resources. If such preferences were merely arbitrary products of culture, says Buss, one might expect to find at least one society somewhere where men’s and women’s mating preferences were reversed; the fact that attitudes are uniform across cultures suggests they are a fundamental part of human psychology.

Evolutionary psychologists think many of these mating preferences evolved in response to the different biological challenges faced by men and women in producing children—the definition of success in evolutionary terms. In a seminal paper, evolutionary biologist Robert Trivers of the University of California at Santa Cruz points out that in most mammals, females invest far more time and energy in reproduction and child rearing than do males. Not only must females go through a long gestation and weaning of their offspring, but childbirth itself is relatively dangerous. Males, on the other hand, potentially can get away with a very small biological investment in a child.

Human infants require the greatest amount of care and nurturing of any animal on Earth, and so over the eons women have evolved a psychology that is particularly concerned with a father’s ability to help out with this enormous task—with his clout, protection and access to resources. So powerful is this psychological legacy that nowadays women size up a man’s finances even when, as a practical matter, they may not have to. A recent study of the mating preferences of a group of medical students, for instance, found that these women, though anticipating financial success, were nevertheless most interested in men whose earning capacity was equal to or greater than their own.

For men, on the other hand, reproductive success is ultimately dependent on the fertility of their mates. Thus males have evolved a mind-set that homes in on signs of a woman’s health and youth, signs that, in the absence of medical records and birth certificates long ago, were primarily visual. Modern man’s sense of feminine beauty—clear skin, bright eyes and youthful appearance—is, in effect, the legacy of eons spent diagnosing the health and fertility of potential mates!

This concern with women’s reproductive health also helps explain why men value curvaceous figures. An upcoming paper by Devendra Singh of the University of Texas at Austin reveals that people consistently judge a woman’s figure not by whether she is slim or fat but by the ratio of waist to hips. The ideal proportion-the hips roughly a third larger than the waist-reflects a hormonal balance that results in women’s preferentially storing fat on their hips as opposed to their waists, a condition that correlates with higher fertility and resistance to disease. Western society’s modern day obsession with being slim has not changed this equation. Singh found, for instance, that while the winning Miss America has become 30 percent thinner over the past several decades, her waist-to-hip ratio has remained close to this ancient ideal.

Women also appreciate a fair face and figure, of course. And what they look for in a male’s physique can also be explained as an evolved mentality that links good looks with good genes. A number of studies have shown that both men and women rate as most attractive faces that are near the average; this is true in societies as diverse as those of Brazil, Russia and several hunting and gathering tribes. The average face tends to be more symmetrical and, according to psychologist Steven Gangestad and biologist Randy Thornhill, both of the University of New Mexico, this symmetry may reflect a person’s genetic resistance to disease.

People have two versions of each of their genes—one from each parent—within every cell. Sometimes the copies are slightly different, though typically each version works just as effectively. The advantage to having two slightly different copies of the same gene, the researchers argue, is that it is harder for a disease to knock out the function of both copies, and this biological redundancy is reflected in the symmetry in people’s bodies, including their faces. Further evidence for a psychological mechanism that links attractiveness with health comes from Buss’ worldwide study of mating preferences: In those parts of the world where the incidence of parasites and infectious diseases is highest, both men and women place a greater value on attractive mates.

Some feminists reject the notion that women should alter physical appearance to gain advantage in the mating game. But archeological finds suggest that the “beauty myth” has been very much a part of the human mating psychology since the times of our ancient ancestors—and that it applies equally to men. Some of the very first signs of human artistry are carved body ornaments that date back more than 30,000 years, and findings of worn nubs of ochre suggest that ancient humans may have used the red and black chalk-like substance as makeup. These artifacts probably served as social signs that, like lipstick or a Rolex watch today, advertised a person’s physical appearance and status. In one grave dating back 20,000 years, a male skeleton was found bedecked with a tunic made from thousands of tiny ivory beads—the Stone Age equivalent of an Armani suit.

Far from being immutable, biological mandates, these evolved mating mechanisms in the mind are flexible, culturally influenced aspects of human psychology that are similar to people’s tastes for certain kinds of food. The human sweet tooth is a legacy from a time when the only sweet things in the environment were nutritious ripe fruit and honey, says Buss, whose book “The evolution of Desire” is due out next year. Today, this ancient taste for sweets is susceptible to modern-day temptation by candy bars and such, though people have the free will to refrain from indulging it. Likewise, the mind’s mating mechanisms can be strongly swayed by cultural influence such as religious and moral beliefs.

Both men and women display different mating psychologies when they are just playing around as opposed to searching for a lifelong partner, and these mental mechanisms are also a legacy from ancient times. A new survey by Buss and his colleague David Schmitt found that when women are looking for “short-term” mates, their preference for attractive men increases substantially. In a study released last month, Doug Kenrick and Gary Groth of Arizona State University found that while men, too, desire attractive mates when they’re playing the field, they will actually settle for a lot less.

Men’s diminished concern about beauty in short-term mates reflects the fact that throughout human evolution, men have often pursued a dual mating strategy. The most successful strategy for most men was to find a healthy, fertile, long-term mate. But it also didn’t hurt to take advantage of any low-risk opportunity to sire as many kin as possible outside the relationship, just to hedge the evolutionary bet. The result is an evolved psychology that allows a man to be sexually excited by a wide variety of women even while committed to a partner. This predilection shows up in studies of men’s and women’s sexual fantasies today. A study by Ian Symons of UC Santa Barbara and Bruce Ellis of the University of Michigan found that while both men and women actively engage in sexual fantasy, men typically have more fantasies about anonymous partners.

Surveys in the United States show that at least 30 percent of married women have extramarital affairs, suggesting that, like men, women also harbor a drive for short term mating. But they have different evolutionary reasons for doing so. Throughout human existence, short-term flings have offered women an opportunity to exchange sex for resources. In Buss and Schmitt’s study, women value an “extravagant lifestyle” three times more highly when they are searching for a brief affair than when they are seeking a long-term mate. Women who are secure in a relationship with a committed male might still seek out attractive men to secure healthier genes for their offspring.

A woman may engage the sexual interest of several men simultaneously in order to foster a microscopic battle known as sperm competition. Sperm can survive in a woman’s reproductive tract for nearly a week, note biologists Robin Baker and Mark Bellis of the University of Manchester, and by mating with more than one man within a short period of time, a woman sets the stage for their sperm to compete to sire a child—passing this winning trait on to her male offspring as well. In a confidential survey tracking the sexual behavior and menstrual cycles of more than 2,000 women who said they had steady mates, Baker and Bellis found that while there was no pattern to when women had sex with their steady partners, having sex on the side peaked at the height of the women’s monthly fertility cycles.

Since in ancient times a man paid a dear evolutionary price for being cuckolded, the male psychology produces a physiological counter-strategy for dealing with a woman’s infidelity. Studying the sexual behavior of a group of couples, Baker and Bellis found that the more time a couple spends apart, the more sperm the man ejaculates upon their sexual reunion—as much as three times higher than average.

This increase in sperm count is unrelated to when the man last ejaculated through nocturnal emission or masturbation, and Baker and Bellis argue that it is a result of a man’s evolved psychological mechanism that bolsters his chances in sperm competition in the event that his mate has been unfaithful during their separation. These concerns are not unfounded: studies of blood typings show that as many as one of every 10 babies born to couples in North America is not the offspring of the mother’s husband.

Despite men’s efforts at sexual subterfuge, women still have the last word on the fate of a man’s sperm in her reproductive tract—thanks to the physiological effect of the female orgasm. In a new study, Baker and Bellis reveal that if a woman experiences an orgasm soon after her mate’s, the amount of sperm retained in her reproductive tract is far higher than if she has an earlier orgasm or none at all. Apparently a woman’s arousal, fueled by her feelings as well as her mate’s solicitous attentions, results in an evolutionary pay-off for both.

Whether people pursue committed relationships or one-night stands depends on their perceptions of what kind of mates are in the surrounding sexual environment. Anthropologist Elizabeth Cashdan of the University of Utah surveyed hundreds of men and women on whether they thought the members of their “pool” of potential mates were in general trustworthy, honest and capable of commitment. She also asked them what kinds of tactics they used to attract mates. Cashdan found that the less committed people thought their potential mates would be, the more they themselves pursued short-term mating tactics. For example, if women considered their world to be full of “cads,” they tended to dress provocatively and to be more promiscuous; if they thought that the world was populated by potential “dads”—committed and nurturing men—they tended to emphasize their chastity and fidelity. Similarly, “cads” tended to emphasize their sexuality and “dads” said they relied more on advertising their resources and desire for long-term commitment.

These perceptions of what to expect from the opposite sex may be influenced by the kind of home life an individual knew as a child. Social scientists have long known that children from homes where the father is chronically absent or abusive tend to mature faster physically and to have sexual relations earlier in life. Psychologist Jay Belsky of Pennsylvania State University argues that this behavior is an evolved psychological mechanism, triggered by early childhood experiences, that enables a child to come of age earlier and leave the distressing situation.

Whether in modern or ancient times, infidelity can breed anger and hurt, and new research suggests subtle differences in male and female jealousy with roots in the ancient past. In one study, for example, Buss asked males and females to imagine that their mates were having sex with someone else or that their mates were engaged in a deep emotional commitment with another person. Monitoring his subjects’ heart rates, frowning and stress responses, he found that the stereotypical double standard cuts both ways. Men reacted far more strongly than women to the idea that their mates were having sex with other men. But women reacted far more strongly to the thought that their mates were developing strong emotional attachments to someone else.

As with our evolved mating preferences, these triggers for jealousy ultimately stem from men’s and women’s biology, says Buss. A woman, of course, has no doubt that she is the mother of her children. For a man, however, paternity is never more than conjecture, and so men have evolved psychologies with a heightened concern about a mate’s sexual infidelity. Since women make the greater biological investment in offspring, their psychologies are more concerned about a mate’s reneging on his commitment, and, therefore, they are more attentive to signs that their mates might be attaching themselves emotionally to other women.

The male preoccupation with monopolizing a woman’s sexual reproduction has led to the oppression and abuse of women worldwide, including, at its extremes, confinement, domestic violence and ritual mutilation such as clitoridectomy. Yet the new research into the mating game also reveals that throughout human evolution, women have not passively acquiesced to men’s sexual wishes. Rather, they have long employed a host of behavioral and biological tactics to follow their own sexual agenda—behaviors that have a huge impact on men’s behavior as well. As Buss points out, if all women suddenly began preferring to have sex with men who walked on their hands, in a very short time half the human race would be upside down.

With its emphasis on how both men and women are active players in the mating game, evolutionary psychology holds out the promise of helping negotiate a truce of sorts in the battle of the sexes—not by declaring a winner but by pointing out that the essence of the mating game is compromise, not victory. The exhortations of radical feminists, dyed-in-the-wool chauvinists and everyone in between are all spices for a sexual stew that has been on a low boil for millions of years. It is no accident that consistently, the top two mating preferences in Buss’ survey—expressed equally by males and females worldwide—were not great looks, fame, youth, wealth or status, but kindness and intelligence.

In the rough-and-tumble of the human mating game, they are love’s greatest allies.

Here is a more recent article, along the same lines, that answeres the question: “Are men slime?”
Evolutionary Science Ponders: Where is Fancy Bred?
By David M. Buss (June 1, 1999 N.Y. Times

“Men are slime.”