The fitness limiting resource for most male primates is the indivisible fertilization of females. Therefore, males commonly compete aggressively with each other over access to receptive females. Among species, however, there is considerable variation in aggressiveness, and in some species males may even show cooperative behaviors, which is often associated with more relaxed and tolerant social relationships. The proximate and ultimate reasons for this variation may depend on several aspects of a social system, but are not yet entirely understood. Baboons (Papio spp.) constitute a well-suite...