Has there ever been a time when there were so many different views of human nature floating around all at once? The economists have their view, in which rational people coolly chase incentives. Traditional Christians have their view, emphasizing original sin, grace and the pilgrim’s progress in a fallen world. And then there are the evolutionary psychologists, who get the most media attention.

For 99 percent of human history, they observe, our species lived in small hunter-gatherer bands. The people who survived developed certain mental modules, which have been passed down to us through our genes. Some of these traits serve us well in the modern age. Children have the capacity to learn language with astonishing speed. Some of these traits don’t. Humans have an insatiable craving for fatty and sugary foods.

In 2000, Geoffrey Miller, a leading evolutionary psychologist, published a book called “The Mating Mind,” in which he argued that the process of sexual selection among early human groups hardwired many of the behaviors we see in humans today. Some of the traits are physical. Men generally prefer women with a 0.7 waist-to-hip ratio (that’s a 24-inch waist and 36-inch hips, for those of you reading this at the gym). Women generally prefer men who are taller and slightly older.

Some of these traits are more subtle. Men, Miller argues, tip better in restaurants, because they’ve been programmed to show how much surplus wealth they have. The average American adult knows 60,000 words, far more than we need. We have all those words because we like to mate with people who caress us with language.