سنجش قدرت و شکل انتخاب جنسی بر صفات مردان

Although recent research has increasingly focused on human sexual selection, fundamental questions remain concerning the relative influence of individual traits on success in competition for mates and the mechanisms, form, and direction of these sexual selective pressures. Here, we explore sexual selection on men's traits by ascertaining men's dominance and attractiveness from male and female acquaintances. On a large American university campus, 63 men from two social fraternities provided anthropometric measurements, facial photographs, voice recordings, and reported mating success (number of sexual partners). These men also assessed each other's dominance, and 72 women from two socially affiliated sororities assessed the men's attractiveness. We measured facial masculinity from inter-landmark distances and vocal masculinity from acoustic parameters. We additionally obtained facial and vocal attractiveness and dominance ratings from unfamiliar observers. Results indicate that dominance and the traits associated with it predict men's mating success, but attractiveness and the traits associated with it do not. These findings point to the salience of contest competition on men's mating success in this population.

Fig. 1. Linear (β) and quadratic (γ) relationships (statistics shown for statistically significant relationships) between men's traits, success under female choice and male contests, and mating success. Linear, quadratic and interaction terms for variables in each level to the left (e.g., men's traits) were entered into multiple regression models to predict variables at higher levels to the right (e.g., success under female choice). Biceps, chest, and shoulder circumference, and weight were standardized and summed to produce the composite variable, Girth. *p < .05, **p < .001, ***p < .0001. Figure options Although we are interested in how past selection produced present sexual dimorphisms, we take a behavioral ecological approach, which emphasizes contemporary selection. We take this approach because we expect that, in general, current function will provide insight into past function. However, attractiveness, dominance, and even mating success have likely been at least partly decoupled from reproductive success by features of modern industrial environments such as effective contraception and socially imposed monogamy (Perusse, 1993). We therefore examined components of reproductive success that are “upstream” of fertility. Assuming that these components affected ancestral men's reproductive output, and in parallel with nonhuman literature, which also frequently measures only proximate components of fitness, we refer to “selective surfaces”, “directional selection”, and the like.