David A. Puts. Beauty and the beast: mechanisms of sexual selection in humans. Evolution and Human Behavior, Vol. 31, No. 3. (May 2010), pp. 157-175.A common refrain from certain non-whites and Southern Europeans is that if a Northern European man looks askance at the pursuit of Northern European women by non-Northern Europeans, it means he is "insecure" or afraid of competing with non-Northern European men. In reality, one competes by competing, and that starts (in a healthy society) with excluding men from other groups from access to women of one's own group.
Literature in evolutionary psychology suggests that mate choice has been the primary mechanism of sexual selection in humans, but this conclusion conforms neither to theoretical predictions nor available evidence. Contests override other mechanisms of sexual selection; that is, when individuals can exclude their competitors by force or threat of force, mate choice, sperm competition, and other mechanisms are impossible. Mates are easier to monopolize in two dimensional mating environments, such as land, than in three-dimensional environments, such as air, water, and trees. Thus, two-dimensional mating environments may tend to favor the evolution of contests. The two-dimensionality of the human mating environment, along with phylogeny, the spatial and temporal clustering of mates and competitors, and anatomical considerations, predict that contest competition should have been the primary mechanism of sexual selection in men. A functional analysis supports this prediction. Men's traits are better designed for contest competition than for other sexual selection mechanisms; size, muscularity, strength, aggression, and the manufacture and use of weapons probably helped ancestral males win contests directly, and deep voices and facial hair signal dominance more effectively than they increase attractiveness. However, male monopolization of females was imperfect, and female mate choice, sperm competition, and sexual coercion also likely shaped men's traits. In contrast, male mate choice was probably central in women's mating competition because ancestral females could not constrain the choices of larger and more aggressive males through force, and attractive women could obtain greater male investment. Neotenous female features and body fat deposition on the breasts and hips appear to have been shaped by male mate choice.
126.96.36.199. Male coalitions and between-group competition.
The tendency of males to form alliances may have evolved in the common ancestor of humans and our closest living relatives, Pan, as a means of cooperative female capture and defense (Fig. 3), although coalitions may also have evolved independently in these lineages for this purpose (Geary & Flinn, 2001; Wrangham, 1999). Male coalitions are rare among primates but common in humans and Pan, especially common chimpanzees (P. troglodytes), and are strengthened by kinship (Nishida & Hiraiwa- Hasegawa, 1987). The capture of women was a primary objective of early warfare (Darwin, 1871; Hrdy, 1997; Lerner, 1986; Spencer, 1885), and among foragers, groups of men commonly raid other villages and abscond with women (e.g., Chagnon, 1988). Such raids may also function in mate defense by deterring future attacks. These behaviors would tend to favor not only aggression and physical prowess, but also social intelligence for negotiating alliances (e.g., Alexander, 1989; Geary & Flinn, 2002; Mueller & Mazur, 1996; Wrangham, 1999).