The old doubts about female competitiveness derived partly from an evolutionary analysis of the reproductive odds in ancient polygynous societies in which some men were left single because dominant males had multiple wives. So men had to compete to have a chance of reproducing, whereas virtually all women were assured of it.
But even in those societies, women were not passive trophies for victorious males. They had their own incentives to compete with one another for more desirable partners and more resources for their children. And now that most people live in monogamous societies, most women face the same odds as men. In fact, they face tougher odds in some places, like the many college campuses with more women than men.
To see how female students react to a rival, researchers brought pairs of them into a laboratory at McMaster University for what was ostensibly a discussion about female friendships. But the real experiment began when another young woman entered the room asking where to find one of the researchers.
This woman had been chosen by the researchers, Tracy Vaillancourt and Aanchal Sharma, because she “embodied qualities considered attractive from an evolutionary perspective,” meaning a “low waist-to-hip ratio, clear skin, large breasts.” Sometimes, she wore a T-shirt and jeans, other times a tightfitting, low-cut blouse and short skirt.
In jeans, she attracted little notice and no negative comments from the students, whose reactions were being secretly recorded during the encounter and after the woman left the room. But when she wore the other outfit, virtually all the students reacted with hostility.
They stared at her, looked her up and down, rolled their eyes and sometimes showed outright anger. One asked her in disgust, “What the [expletive] is that?”
Most of the aggression, though, happened after she left the room. Then the students laughed about her and impugned her motives. One student suggested that she dressed that way in order to have sex with a professor. Another said that her breasts “were about to pop out.”
The results of the experiment jibe with evidence that this “mean girl” form of indirect aggression is used more by adolescents and young women than by older women, who have less incentive to handicap rivals once they marry. Other studies have shown that the more attractive an adolescent girl or woman is, the more likely she is to become a target for indirect aggression from her female peers.
“Women are indeed very capable of aggressing against others, especially women they perceive as rivals,” said Dr. Vaillancourt, now a psychologist at the University of Ottawa. “The research also shows that suppression of female sexuality is by women, not necessarily by men.”
Stigmatizing female promiscuity — a.k.a. slut-shaming — has often been blamed on men, who have a Darwinian incentive to discourage their spouses from straying. But they also have a Darwinian incentive to encourage other women to be promiscuous. Dr. Vaillancourt said the experiment and other research suggest the stigma is enforced mainly by women.
“Sex is coveted by men,” she said. “Accordingly, women limit access as a way of maintaining advantage in the negotiation of this resource. Women who make sex too readily available compromise the power-holding position of the group, which is why many women are particularly intolerant of women who are, or seem to be, promiscuous.”
Indirect aggression can take a psychological toll on women who are ostracized or feel pressured to meet impossible standards, like the vogue of thin bodies in many modern societies. Studies have shown that women’s ideal body shape is to be thinner than average — and thinner than what men consider the ideal shape to be. This pressure is frequently blamed on the ultrathin female role models featured in magazines and on television, but Christopher J. Ferguson and other researchers say that it’s mainly the result of competition with their peers, not media images.
“To a large degree the media reflects trends that are going on in society, not creates them,” said Dr. Ferguson, a psychologist at Stetson University. He found that women’s dissatisfaction with their bodies did not correlate with what they watched on television at home. Nor were they influenced by TV programs shown in laboratory experiments: Watching the svelte actresses on “Scrubs” induced no more feelings of inferiority than watching the not-so-svelte star of “Roseanne.”
But he found that women were more likely to feel worse when they compared themselves with peers in their own social circles, or even if they were in a room with a thin stranger, like the assistant to Dr. Ferguson who ran an experiment with female college students. When she wore makeup and sleek business attire, the students were less satisfied with their own bodies than when she wore baggy sweats and no makeup. And they felt still worse when there was an attractive man in the room with her.
“Sexual competition among females seems to increase due to circumstances that tend to be particularly common in affluent societies,” Dr. Ferguson said.
In traditional villages, people married at an early age to someone nearby, but young men and women in modern societies are free to postpone marriage as they search long and far for better options. The result is more competition because there are so many more rivals — and there’s no longer any scientific doubt that both sexes are in to win it.