Editor's introduction

Why have the diverse social systems of primates evolved? Are the causal variables the same for different taxa? These questions are explored in the final six chapters. Here, problems specific to several different taxa are identified and causality is proposed. Where the underlying mechanisms producing social system variation have yet to be determined, the routes to further understanding are highlighted.

The contributors have tackled some of the more problematic issues in primate socioecology. Two radiations, those of the Malagasy primates and of the neotropical monkeys, pose intriguing and difficult questions about adaptive arrays. These groups are of particular interest in that they both represent a number of adaptive types and exhibit a range of social systems. We are only now approaching a sufficient knowledge base to address questions about their social structure in a broad evolutionary and ecological context. Kappler takes on the lemuroids in general in relation to social dynamics (Chapter 10), while Strier challenges the generality of the ‘cercopithecine’ model for social system evolution using examples from the platyrrhines (Chapter 11). It is of particular importance to be able to examine the existing models for intergroup and intragroup competition for food and mates in these groups of species in the light of an existing paradigm drawn primarily from terrestrial Old World monkeys and apes. As the authors in this section point out, this theoretical paradigm based on female resource competition (sensu Wrangham, 1980) needs reappraisal in the light of our growing knowledge of non-cercopithecoid foraging and reproductive strategies.