From The Economist:
Geoffrey Miller is a man with a theory that, if true, will change the way people think about themselves. His idea is that the human brain is the anthropoid equivalent of the peacock’s tail. In other words, it is an organ designed to attract the opposite sex. Of course, brains have many other functions, and the human brain shares those with the brains of other animals. But Dr Miller, who works at the University of New Mexico, thinks that mental processes which are uniquely human, such as language and the ability to make complicated artefacts, evolved originally for sexual display.
One important difference between peacocks’ tails and human minds, of course, is that the peahen’s accoutrement is a drab affair. No one could say the same of the human female psyche. That, Dr Miller believes, is because people, unlike peafowl, bring up their offspring in families where both sexes are involved in parenting. It thus behoves a man to be as careful about choosing his wife as a woman is about choosing her husband.
Both sexes, therefore, have reason to show off. But men and women will have different criteria for making their choices, and so the sexual-display sides of their minds may differ in detail.
Testing this hypothesis will be a long haul. But in a paper he has just published in the Journal of Personality and Social Psychology, in collaboration with Vladas Griskevicius of Arizona State University, Dr Miller goes some way towards it. He, Dr Griskevicius and their colleagues look into two activities—conspicuous consumption and altruism towards strangers—to see if these support the “mating mind” hypothesis, as Dr Miller has dubbed his idea. Their conclusion is that they do.
More here.