Evolution of Social Systems

A species’ social system does not materialise out of nowhere fully formed. It evolves by modification from the social systems of its immediate ancestors. This being so, an important test of our understanding of primate social systems is whether we can use our theoretical principles to reconstruct phylogenies for the social evolution of particular taxonomic groups. Such phytogenies must be consistent with what is known both of the species’ phylogenetic history (i.e. the sequence of speciation events) and with the palaeo-environments through which they passed. Moreover, to be really useful, such reconstructions have to be able to specify not just why changes took place but also how they were brought about. In other words, we need to be able to point to the relationships that changed and show both why these changes might have been necessary and how their occurrence would have caused the appropriate changes in the ancestral taxon’s social system.