Look Who's Cheating

Men, women, and evolution


"Why do men cheat?" asked a TV news promo that showed a man and a woman in a passionate embrace. "A surprising new study says the answer might be in their genes." A cynic might say: And that's news? That's olds (to quote British novelist Terry Pratchett's brilliant satire of the news business, The Truth). True or not, the notion that men are "hard-wired" by evolution to spread their seed while women are predisposed to seek monogamous relationships has been around for years.

Many feminists have been highly critical of evolutionary psychology, which they see as validating gender stereotypes and upholding the status quo. The feminist denial of biological differences between men and women can certainly go to extremes; some even argue that the very idea of two sexes is just a cultural construct. Yet to some extent, the feminist critique is on target. Particularly by the time it trickles down into popular culture, the evolutionary view of male and female behavior can often be simplistic and divisive.

The new study, conducted by Bradley University psychologist David Schmitt and published in the Journal of Personality and Social Psychology, is impressive in its scope: It involved 16,288 college students from 50 countries in the Americas, Europe, Africa, Asia, and Australia. Men and women were asked how many partners they would like to have in the next month. The average response from men was 1.87 and from women, 0.78; more than a quarter of men and just five percent of women said they wanted more than one partner in the next month. Over the next 10 years, men wanted an average of nearly six partners; women, just over two.

Since the greater male preference for sexual variety was found in every country included in the study, some evolutionary psychologists have hailed the Schmitt study as definitive, irrefutable evidence that these differences are indeed biological.

Not so fast, critics say. Some degree of a sexual double standard that stigmatizes promiscuity for women but condones or even encourages it for men exists in every one of the cultures included in the study. It's not surprising that women's and men's responses would reflect these attitudes. A man may feel that expressing a desire for more sexual partners makes him look more virile; a woman may feel that it makes her look like a slut.

Consider another recent study by Ohio State University psychologist Terri Fisher, appearing in the Journal of Sex Research. Fisher had college students fill out questionnaires about their sexual experiences and attitudes. Some of them completed the questionnaires while hooked up to a polygraph machine, which they were told would detect any dishonesty (though in fact the machines didn't work). Others filled out the surveys alone in a room, assured of anonymity. The third group filled out the surveys alone in a room with the door open and the researcher sitting outside, and were told the researcher might see their answers.

The women in the last group reported an average of 2.4 sexual partners in their lifetime. However, women reported an average of 3.4 partners when assured of anonymity—and 4.4 when hooked up to the "lie detector." The women in the last two groups also reported having sex for the first time at an earlier age. For men, the results were virtually the same regardless of the setting in which they answered the questionnaire—except that men reported losing their virginity at an earlier age when they were not assured of anonymity. In other words, men's and women's reports of their sexual behavior are influenced by stereotypical social expectations. Surprise, surprise.

One might argue that the universality of the sexual double standard suggests that it's rooted in biology. And to some extent, it is. For most of history, before reliable contraception existed, the cost of sex was much higher for women than for men; no wonder parents were more concerned about protecting the chastity of daughters. Men's uncertainty about their paternity also led to harsh restrictions on women's sexual behavior.

But there is no reason to believe that this legacy is impervious to social change. In Schmitt's study, sex differences were consistent across cultures yet women's and men's choices were more similar in more egalitarian societies. Other research shows that while men are more interested in casual sex than women, the ideal for the vast majority of women and men alike is sex in a loving, monogamous relationship.

There is, obviously, no benefit in denying real gender differences. But sex stereotypes that are the stuff of late-night comedy routines don't help, either. Too often, they obscure what we all have in common as human beings.