Big Brains

from Origin Story by David Christian.

Humans have big brains: "Primates are exceptionally brainy. Their brains are unusu­ally large relative to their bodies, and the top front layer of the brain, the neocortex, is gigantic. In most mammal species, the cortex accounts for between 10 percent and 40 percent of brain size. In primates, it accounts for more than 50 percent, and in humans for as much as 80 percent. Humans are exceptional for the sheer number of their cortical neurons. They have about fifteen billion, or more than twice as many as chimpanzees (with about six billion). Whales and elephants, the next in line after humans on the most-cortical-neurons list, have about ten billion cortical neurons, but they have smaller brains than chimps relative to body size. Large brains mean that primates are wizards at acquiring, storing, and using information about their surroundings./.../