Mutual Mate Choice: Sexual Selection Versus Sexual Conflict

Many years ago, when I began researching young women’s aggression, I was struck by the extent to which verbal and physical fights centered—directly or indirectly—on men. At that time, this message was not well received by the feminist community for ideological reasons. When I turned toward evolutionary theory, I was surprised to find a similarly chilly reception, this time for theoretical reasons: Women’s greater parental investment makes them a limiting resource for male reproductive success and so men must compete, often ferociously, for sexual access. Women have no reason to compete, because any man will be only too happy to sexually oblige them. In that case, why were young women fighting about boys? Why were they acutely hostile to female rivals? Why did they spend so much time and money enhancing their physical appearance? Why did they cede to men the power to accept or reject them? My answer, like Stewart-Williams and Thomas (this issue), was that two-way selection was taking place and, if so, that the human mating system was more monogamous than it was being given credit for. Women’s competition operates at several levels of intensity. At the lowest level is intersexual selection or epigamic display. Women advertise the qualities of physical appearance and character that men value (Buss, 1988). Cosmetics, surgery, dieting, and clothing choice are used to make their appearance conform more closely to men’s ideal. (This is not to deny that in some cases, such as dieting, runaway competition between women can pull the resultant effect away from men’s optima.) At another level up is the derogation of rivals (indirect aggression), which often involves criticising their appearance or sexual promiscuity (Vaillancourt, in press). Documentation of women’s use of indirect aggression against rivals comes from experimental as well as self-report studies: Dyads of young women had their conversation interrupted by a third (confederate) woman dressed either sexily or conservatively (Vaillancourt & Sharma, 2011). The pair’s subsequent conversation was recorded. Nearly all of the participants who were rated (blindly) as using indirect aggression were in the “sexy intruder” condition. Indirect aggression appears to be a successful strategy in delaying or removing rivals from the mating arena: Victims have their first sex at a later age than perpetrators and are lower in dating status (Gallup, O’Brien, & Wilson, 2011; White, Gallup, & Gallup, 2010). It has been suggested that the advantage of indirect aggression is the fact that the perpetrator can remain anonymous, thus reducing the risk of retaliation. Yet in the few cases where young women come to blows, it is often a result of gossip and rumor that finds its way back to the target. The same epithets appear time and again as triggers to girls’ fights (Artz, 2005; Miller & Mullins, 2006): attacks on a girl’s sexual reputation (“slag,” “slut,” “whore (ho),” “tart”) or on her appearance (“ugly,” “fat”). Surveys indicate that in the previous month, 60% of girls had called another girl names, 50% had sworn at her, and 35% had pushed or shoved her (Artz, Nicholson, & Magnuson, 2008). Rates of physical aggression between young women are responsive to ecological conditions including age structure, adult sex ratio, sex-biased early mortality, population density, and high variance in mate quality (Campbell, 2013, in press). Many of these factors are concentrated in economically deprived inner-city areas where women’s mating opportunities are reduced by a skewed operational sex ratio as a result of high rates of death, imprisonment, and drug addiction among young men. Many of the remaining men represent an economic liability rather than an asset, whereas others are “living large” on the proceedings of crime, thus creating wide variance in male resources. The paucity of well-resourced men creates a buyer’s market with young women competing for even short-lived access to them. Yet even under extreme economic circumstances, escalation to physical aggression is rarer between young women than men. In the United States, girls account for 33% of arrests for simple assault and 24% of aggravated assaults (Girls Study Group, 2008). The wider gender gap for aggravated assault reflects girls’ less injurious behavior and their lower likelihood of using weapons. The male-to-female ratio for assault has remained remarkably stable over time. Young women’s lower involvement in physical aggression is universal and trans-historical. Although traditional evolutionary theories have focused on men’s stronger incentives for aggression as a result of greater fitness variance among men, I have argued that we must also take into account disincentives for women. Specifically, a woman’s lower reproductive ceiling, higher replacement costs, and her role as the primary caretaker of her offspring make a mother’s life the single most important factor in ensuring her reproductive success. Ancestral women who jeopardized their lives by illadvised risk taking (including escalated aggression)