The utility of reproductive skew models in the study of male primates, a critical evaluation

The number of adult males in a group is one of the most variable aspects ofprimate social organization. The causes for this variation have constituted alongstanding focus in primatological research.1As a male’s reproductive suc-cess is mainly limited by access to females,2competition among males shouldresult in the exclusion of rivals from groups of females.4,5However, a great num-ber of primate species live in groups with several adult males. To explain thecauses and consequences of this shared male group membership, primatolo-gists have begun to examine the phenomenon within the framework of repro-ductive skew theory. This body of game theoretical models was developed toexamine variation in reproductive skew within and across populations and spe-cies and to explain the preconditions for stable associations, as well as howreproduction should be distributed therein.6–9 Here we summarize the main aspects of this theory, review its application to studies of male reproductivestrategies, and identify pitfalls associated with using this approach.