It is fairly rare to come across a groundbreaking theory that makes scientists take stock of their existing assumptions. This may be precisely what is about to happen with a new theory proposed by Bernard Crespi, an evolutionary biologist at Simon Fraser University in Canada, and Christopher Badcock, a sociologist at the London School of Economics. The basis of the theory is that genetically based mental illnesses such as schizophrenia or autism result from an evolutionary tug of war that...