The Ape that Understood the Universe: How the Mind and Culture Evolve

Beauty, from a Darwinian vantage point, is a certificate of good health, and courtship a process of shopping around for the best genes for our future offspring. In a sense, mate choice is a form of eugenics, and always has been.

Our ancestors didn’t need to enjoy having kids to keep the conveyer belt of human life running. In fact, they didn’t even need to want to have kids in the first place. All they needed was to want to have sex, and then nine months later, to want to look after the crying, cooing aftermath of that sex. Doing so can sometimes deal a body blow to people’s happiness. But natural selection doesn’t “care” about our happiness. It cares about whether we pass on our genes.

Males can only grow a good one if they’re genuinely “rich” – that is, if they’re in good condition, have relatively few mutations, and are relatively immune to the local pathogens and parasites. In effect, males with the most impressive tails are announcing to the world that “I can afford to grow this useless ornament, and can keep myself alive despite having to lug it around. I am therefore a particularly fit and virtuous specimen of manhood.” And that, apparently, is what peahens most want to hear.