Abstract
Field study of wild animals is often asserted to have no role in discovering the cognitive capacities of the animal mind. In this lecture, I challenge that view, giving two examples where field data have revealed unsuspected cognitive capacities and allowed theoretical advance in understanding the evolutionary origins of human cognitive capacities. In the first, narrative records of deception of social companions were used as an ‘index’ of species' capacity for subtle social manipulation. This capacity was found to be widespread among primates, and to depend on neocortex volume, thus supporting theories that implicate social complexity in increasing primate intelligence. Intentional deception follows a quite different pattern, being rare and clumped in the great apes. The origins of the ability to understand others' behaviour, in terms of their intended purposes and the cause-and-effect involved in achieving them, forms the topic of my second example, great ape food processing. Wild apes regularly develop computationally complex organizations of behaviour, neatly adapted to solving food-acquisition problems and thus acquiring foods unreachable by sympatric competitor monkeys. Converging analyses of these manual techniques point to the underlying ability of ‘parsing behaviour’, giving apes (but perhaps no other animals) the ability to understand behaviour in a simple way, in which satisfying results stand for ‘goals’ and regular prior correlates stand for ‘causes’. In both cases, there are obvious implications for human cognitive evolution.
