Evolution of primate social systems: implications for hominin social evolution

Understanding hominin social evolution has long been bedevilled by the fact that we have no general theories of primate evolution. As a result, most attempts to reconstruct hominin social evolution have been, at best, speculative. It has not been uncommon, for example, to identify a taxon of living mammals which face challenges similar to those faced by early hominins and use them as a template, if not as a direct analogue, for the kind of social system that we imagine a hominin might have had. Over the decades, chimpanzees, gorillas, baboons, and canids have all had their turn as the best available model (Washburn and DeVore 1961, Jolly 1970, Foley and Lee 1989, McGrew 1992, Lewis 1997, Elton 2006). However, the use of analogues is, at best, a crude device: it necessarily assumes that the taxon of interest had exactly the same ecology, physiology, and life history as the analogue taxon—something that is almost never true. Indeed, most of the ana- logue species have been used because they share just one key trait with hominins: chimpanzees as phylogenetic cousins, baboons as ecological analogues on wooded savannahs, carnivores as hunters.