Abstract

There is a very striking difference between even the simplest ethnographically known human societies and those of the chimps and bonobos. Chimp and bonobo societies are closed societies: with the exception of adolescent females who disperse from their natal group and join a nearby group (never to return to their group of origin), a pan residential group is the whole social world of the agents who make it up. That is not true of forager bands, which have fluid memberships, and regular associations with neighbouring bands. They are components of a larger social world. The open and fluid character of forager bands brings with it many advantages, so the stability of this more vertically complex form of social life is not difficult to explain, once it establishes. But how did it establish, if, as is likely, earlier hominin social worlds resemble those of our close pan relatives in the suspicion (even hostility) of one band to another? How did hominin social organisation transition from life in closed bands, each distrustful of its neighbours, to the much more open social lives of foragers? I will discuss and synthesise two approaches to this problem, one ecological, based on the work of Robert Layton and his colleagues, and another that is organised around an expansion of kin recognition, an idea primarily driven by Bernard Chapais. The paper closes by discussing potential archaeological signatures both of more open social worlds, and of the supposed causal drivers of such worlds.