Evolution of the social brain

The social intelligence hypothesis posits that the large brains and distinctive cognitive abilities of primates (in particular, anthropoid primates) evolved via a spiralling arms race in which social competitors developed increasingly sophisticated ‘Machiavellian’ strategies (Byrne & Whiten, 1988). The idea stemmed originally from observations suggesting that the polyadic interactions and relationships typical of anthropoid societies place exceptional demands on the ability of individuals to process and integrate social information. This hypothesis has been contrasted with foraging niche hypotheses, which propose that it is the need to find food in patchy, unpredictable environments, or even to extract it from awkward substrates, that required large brains and cognitive specialisation (e.g. Gibson, 1986; Milton, 1988). A major task in the study of primate cognition is to devise tests of these hypotheses.