Conflict and bonding between the sexes

Abstract

The derivation of human universals from nonhuman data is complicated by the immense diversity of patterns exemplified by both human and nonhuman primates. One approach is to elucidate processes that may operate universally, though the particular phenotypic patterns that result may differ, depending upon the distinctive features of species biology. Below, I argue that sexual conflict and its corollary, sexually antagonistic coevolution, are of central importance for understanding the evolution of reproductive strategies in nonhuman primates. Because sexual conflict is a relatively new area of theory and research, and because primate life histories limit the kinds of data that can be collected, relevant primate data are limited (with the possible exception of one form of conflict: infanticide). Consequently, I review sexual conflict theory, relevant comparative data from nonprimates, and preliminary evidence from select primate studies. Theoretical considerations and empirical evidence suggest significant potential for the widespread action of sexual conflict in nonhuman primates, in both precopulatory and postcopulatory domains of reproduction, and affecting characters ranging from morphology and physiology to sociosexual behavior. Female counterstrategies to male-imposed costs are diverse, but male-female association has been argued to forestall sexual conflict both in the form of precopulatory coercion and of infanticide. In light of evidence for pervasive and diverse effects of sexual conflict in nonhuman primate biology, it is likely that it also constitutes a universal process underlying human reproduction. I briefly explore several potential sources of human sexual conflict suggested by the nonhuman data.