Abstract

The human brain is an extraordinary organ. It has allowed us to walk on the moon, *to discover the of matter and life,* and to play chess almost as well as a computer. But this virtuosity raises a puzzle. The brain of Homo sapiens achieved its modern form and size between fifty and a hundred thousand years ago, well before the invention of agriculture, civilizations, and writing in the last ten thousand years. Our foraging ancestors had no occasions to do astrophysics or play chess, and natural selection would not have rewarded them with more babies if they had. How, then, did our outsize, *science-ready* brain evolve?