The social brain hypothesis: An evolutionary perspective on the neurobiology of social behaviour

This chapter defends a version of the social brain hypothesis, focusing especially on the cognitive powers involved in the 'Theory of Mind' that humans are thought to deploy in order to attribute mental states to each other. The size of the human brain is not a new discovery (and does not need any sophisticated technology to establish it): the innovative contribution of neuroscience to this area of study, however, has been to enable experiments in which the brain activation of subjects doing various 'social cognition' tasks can be examined and mapped. The discovery that parts of the prefrontal cortex are consistently activated by Theory of Mind tasks provides the social brain hypothesis with support. The fact that it is this area of the brain that has become larger as human brain size has increased over time also fits nicely within a theory that regards the demands of social cognition as a central 'driver' of the evolution of the human brain.