Parry Clarke: UC Davis Department of Anthropology

Classic sexual selection theory, exemplified by the work of Bateman and Trivers, has played and continues to play a central role in the study of primate mating systems. As a result, most theorizing within the field is premised on the assumption that males have been selected to maximize competitive ability at the point of conception and are largely immune to variance in infant survivorship. This perspective runs contrary to more recent theoretical treatments of sexual selection, however, which point out that males will rarely, if ever, be able to compensate for infant mortality through re-mating and should therefore be sensitive to infant survivorship. Using data on male reproductive success in wild chacma baboons (Papio hamadryas ursinus) I will argue that males do act to augment their offspring’s survivorship and they do so at the expense of their maximum potential reproductive output. Specifically, I will show data suggesting that dominant males willingly cede reproductive opportunities to subordinates in an effort to encourage them to remain in the group. I conclude that this is because by doing so they afford their infants a greater level of protection from infanticide, a significant source of infant mortality in chacma.