Lifeboat Foundation

Researchers have found that for much of human evolutionary history our brains kept growing. In fact, if you count from our last shared ancestors with chimpanzees six million years ago, the human brain size almost quadrupled. This happened thanks in part to the improving diet and nutrition of early humans. Cro Magnons, the Homo sapiens that had the largest brains in history were alive from 20,000 to 30,000 years ago. But as the recent study from scientists at Dartmouth and Boston Universities points out, around 3,000 years ago, during the current Holocene geological epoch, our brains began to diminish.