Some have stressed an environmental determination of primate social behaviour, but a recent paper suggests that social behaviour in primates is genetic, not environmental: “Stepwise evolution of stable sociality in primates” (2011). Also see Nature’s commentary, and Nicholas Wade’s article in the NYT.
By studying many different primate lineages (see image below), the important conclusion they reach is that closely related primate groups display similar social organizations even when in different environments:
From the Nature commentary: “The existence of a strong phylogenetic signal spells trouble for socioecological models that aim to explain the evolution of primate social organization. The models hypothesize that food distribution shapes competitive regimes, and that these, in turn, shape dispersal patterns and the nature of relationships within groups. These models generally assume that phylogeny does not impose notable constraints on social organization, and that changes from one form of social organization to another are all equally likely. But there is a growing realization that history does have a role and the new results strengthen that view.”