Diet And Brain Size

[Danmcakes]

Sugar for the win...not sure if this study has been posted...

"Contrary to the predictions of the social brain hypothesis, our results indicate that none of the sociality measures examined here explain relative brain size variation in primates, which is predicted only by diet, with frugivores having relatively larger brains than folivores."

Primate brain size is predicted by diet but not sociality : Nature Ecology & Evolution

 

[James IV]

Sugar for the win...not sure if this study has been posted...

"Contrary to the predictions of the social brain hypothesis, our results indicate that none of the sociality measures examined here explain relative brain size variation in primates, which is predicted only by diet, with frugivores having relatively larger brains than folivores."

Primate brain size is predicted by diet but not sociality : Nature Ecology & Evolution

And omnivorous monkeys have larger brains than pure frugivoirs.
Brain size in monkeys is a result of food. However, not just as a direct result of the food being eaten, but the difficulty in attaining the food. Leaves are plentiful, easy to obtain, and simple to eat. Fruit takes more effort to gather, and make consumable (peel, separate seeds, etc.) Hunting takes the most effort, skill, and cognitive ability, which is why monkeys with the largest portion of calories coming from animal/insect foods, have the largest brains.