Science Focus - the home of BBC Science Focus Magazine
Why are human brains so big? © Getty Images

Why are human brains so big?

Subscribe to BBC Science Focus Magazine and get 6 issues for just £9.99

Bigger is better! Humans have the largest relative brain to body mass ratio of any existing species.

Asked by: Lizzie Alton, Glasgow

Advertisement

One possibility is that large brains are sexier. The person that can make music and art, or tell stories, may be more attractive to potential mates.

But in the 1990s, anthropologist Robin Dunbar suggested that humans might also need large brains to keep track of their complicated social lives. Human social circles normally comprise around 150 people, compared with 50 for chimpanzees. Larger social groups have exponentially more interrelationships and our survival and success depends on being able to react to and predict the behaviour of our peers. Related to this is the idea of social dominance. Once our ancestors had begun to master their environment, their biggest threats were other humans. Leadership tussles within and between tribes favoured smarter humans much more than those that were just stronger.


Advertisement

Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.

Authors

luis villazon
Luis VillazonQ&A expert

Luis trained as a zoologist, but now works as a science and technology educator. In his spare time he builds 3D-printed robots, in the hope that he will be spared when the revolution inevitably comes.

Advertisement
Advertisement
Advertisement

Sponsored content