Study of primates throws up surprising possibility about why humans have big brains
Eating fruit that can be hard to access and tricky to peel may have helped our ancestors grow big brains, scientists believe.
A new study has found that diet may be more important to brain evolution than being sociable.
Scientists came to the conclusion after looking at food consumption and social behaviour in more than 140 primate species.
Those including fruit in their diets had significantly larger brains than "folivores" that only ate leaves.
Having to cope with hard-to-peel fruit may be one factor that drove the expansion of brain size, say the researchers.
Lead scientist Alex DeCasien, from New York University in the US, said: "Fruit is patchier in space and time in the environment, and the consumption of it often involves extraction from difficult-to-reach-places or protective skins.
"Together, these factors may lead to the need for relatively greater cognitive complexity and flexibility in frugivorous species."
The findings, reported in the journal Nature Ecology and Evolution, challenge the widely held view that socialisation was primarily responsible for humans having big brains.
Study co-author Dr James Higham, from New York University's Department of Anthropology, said: "Are humans and other primates big-brained because of social pressures and the need to think about and track our social relationships, as some have argued?
"This has come to be the prevailing view, but our findings do not support it, in fact, our research points to other factors, namely diet."
