A set of three nearly identical genes found only in humans, NOTCH2NL, appears to play a critical role in the development of our large brains, according to a pair of studies published this week in the journal Cell. The NOTCH2NL genes are found exclusively in humans and appeared between 3 and 4 million years ago, just before the period when fossils show a dramatic increase in the brain sizes of human ancestors. These genes belong to an ancient family...
