Despite sharing 98 percent of our DNA with chimpanzees, humans have much bigger brains and are, as a species, much more intelligent. Now a new study sheds light on why: Unlike chimps, humans undergo a massive explosion in white matter growth, or the connections between brain cells, in the first two years of life.

The new results, published today (Dec. 18) in the Proceedings of the Royal Society B, partly explain why humans are so much brainier than our nearest living relatives. But they also reveal why the first two years of life play such a key role in human development.

Read more at LiveScience.