Brain Size Surprise: All primates may share expanded frontal cortex

Researchers have traditionally theorized that the frontal cortex, a brain region linked to mental faculties such as planning and reasoning, expanded to an unprecedented extent during human evolution. However, a new analysis of brains from many different mammals takes the uniqueness out of our frontal cortex.

Lemurs, gibbons, chimpanzees, and other primates have roughly the same proportion of brain tissue devoted to the frontal cortex as people do, say Eliot C.