Humans are social creatures; we live in family groups, socialise with friends, and work with colleagues. Evolutionary psychologist Robin Dunbar’s ‘social brain hypothesis’ suggests that brain size is directly related to social group size in mammals. The bigger the group, the bigger the brain. In this interview with Research Outreach, we find out how Dunbar developed his theory as well as his now famous ‘Dunbar’s number’

Robin Dunbar discusses his eponymous ‘Dunbar’s Number’, primates to people, and why size matters with social groups and evolution.