Brain size didn't drive primate evolution, research suggests

When great apes diverged from old-world monkeys about 20 million years ago, there was a rise in white matter in the prefrontal cortex, which contributes to social cognition, moral judgments, introspection, and goal-directed planning. Regions tied to motor planning also increased and could have helped them orchestrate the complex movements needed to manipulate tools.


Gibbons and howler monkeys showed a different pattern. Even though their bodies and their brains got smaller over time, the hippocampus, which plays a role in spatial tasks, increased in size in relation to the rest of the brain. That may have allowed these monkeys to be spatially adept and inhabit a more diverse range of environments.

Read the full NBC News article HERE.