Sex- and age-specific rates of killing unrelated persons of one’s own sex were computed for Canada (1974–1983), England/Wales (1977–1986), Chicago (1965–1981), and Detroit (1972) from census information and data archives of all homicides known to police. Patterns in relation to sex and age were virtually identical among the four samples, although the rates varied enormously (from 3.7 per million citizens per annum in England/Wales to 216.3 in Detroit). Men’s marital status was related to the probability of committing a same-sex, nonrelative (...) homicide, but age effects remained conspicuous when married and unmarried men were distinguished.These findings and the treatment of age and sex effects by criminologists are discussed in the light of contemporary evolutionary psychological models of sex differences and life-span development. Same-sex homicides in which killer and victim are unrelated can be interpreted as an assay of competitive conflict. In every human society for which relevant information exists, men kill one another vastly more often than do women. Lethal interpersonal competition is especially prevalent among young men, which accords with many other aspects of life-span development in suggesting that sexual selection has maximized male competitive prowess and inclination in young adulthood. (shrink)

Henrich et al.'s nice cross-cultural experiments would benefit from models that specify the decision rules that humans use and the specific developmental pathways that allow cooperative norms to be internalized. Such models could help researchers to design further experiments to examine human social adaptations. We must also test whether the “same” experiments measure similar constructs in each culture, using additional methods and measures.

An evolutionary psychological perspective drawing on sexual selection theory can better explain sex differences in aggression and violence than can social constructionist theories. Moreover, there is accumulating evidence that, in accordance with predictions derived from sexual selection theory, men modulate their willingness to engage in risky and violent confrontations in response to cues to fitness variance and future prospects.

The relationship between feminism and the biological sciences has always been particularly tense and hostile. Feminists have been inclined not to trust what scientists had to say about the sexes, with science often being pronounced a “white, male enterprise.” But why should feminism and the biological sciences remain at odds? And what might be gained from a reconciliation? In Who's Afraid of Charles Darwin? Griet Vandermassen shows that, rather than continuing this enmity, feminism and the biological sciences, and in particular (...) evolutionary psychology, have the potential and the need to become powerful allies. Properly understood, the Darwinian perspective proposed in this volume will become essential to tackling the major issues in feminism. (shrink)