Ancient genome duplications laid the foundations of complex brains, research suggests‎

New findings, published in Nature, help answer the riddle of how vertebrates evolved the diverse array of brain cells that distinguishes them from other animals. It appears that a dramatic expansion of the genetic toolkit more than 450 million years ago enabled the emergence of different kinds of brain cells. These cellular innovations are shared across vertebrates—from primitive fish to mammals—and form the basis of the sophisticated brains seen today.