ABSTRACT

We review the causes of the evolution of social systems and the methods used in their analysis. First, we discuss the roles of genetics, phenotypic traits, ecology (basic necessary resources and natural enemies) and demography in the origin and evolution of sociality, and synthesize the effects of these conditions in a comparative assessment of the predictions of optimal skew models. The models provide a useful framework to explaining and predicting social systems, but would benefit from expansion in the range of their assumptions and more explicit connection to ecological and demographic selective pressures. Second, we review the purposes and usefulness of alternative social system lexicons. We conclude that the trade–off between universality and taxon–specific precision of terms can usefully be addressed by explanation of social terms for each comparative test coupled with striving for recognition of convergence across the broadest possible taxonomic range. Finally, we provide an overview of current adaptationist methods used for analyzing social systems, focussing on approaches that utilize phylogenetic information. Integration of comparative with behavioral–ecological methods, especially experimentation, promises to lead to the next series of insights and critical data for tests of theory.

INTRODUCTION

This volume has had three main objectives. First, we have tried to bring together the widest possible diversity of social insects and arachnids, to elucidate necessary and sufficient conditions for the origin and maintenance of different social systems. In this chapter, we first review the evidence for associations between social systems and genetic, phenotypic, ecological and demographic variables.