Brain size in primates is predicted by diet, an analysis by a team of New York University anthropologists indicates. These results call into question "the social brain hypothesis," which has posited that humans and other primates are big-brained due to factors pertaining to sociality.
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Their results showed that brain size is predicted by diet rather than by the various measures of sociality--after controlling for body size and phylogeny. Notably, frugivores and frugivore/folivores exhibit significantly larger brains than folivores and, to a lesser extent, omnivores show significantly larger brains than folivores.
The researchers caution that the results do not reveal an association between brain size and fruit or protein consumption on a within-species level; rather, they note, they are evidence of the cognitive demands required by different species to obtain certain foods.
"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," observes DeCasien. "Together, these factors may lead to the need for relatively greater cognitive complexity and flexibility in frugivorous species."
( clever title ) 