Who can doubt that biology, along with culture, plays a crucial role in tuning our senses? The gravity that draws a man and woman together, leading each to find the other ravishing, carries with it a long history of sexual selection, one informed by a shrewd calculation of fertility and strength. I remember how astonished I was to realize, one rainy spring day in seventh grade, that the girl sitting in the desk beside me was suddenly, enormously interesting. My attention was riveted on Mary Kay's long blond hair, which fell in luxuriant waves over the back of her chair, until it brushed against a rump that swelled, in a way I had never noticed before, her green plaid skirt. As a twelve-year-old, I would not have called Mary Kay beautiful, although I realize now that that is what she was. And I would have balked at the suggestion that my caveman ancestors had any say in my dawning desire, although now I can hear their voices grunting. Go for the lush hair, the swelling rump.

If we take a ride through the suburbs and study the rolling acres of lawn dotted with clumps of trees and occasional ponds, what do we see but a faithful simulation of the African savanna where humans first lived? Where zoning laws permit, the expanse of green will often be decorated by grazing animals, docile and fat, future suppers on the hoof. The same combination of watering holes, sheltering trees, and grassland shows up in paintings and parks the world over, from New Delhi to New York. It is as though we shape our surroundings to match an image, coiled in our DNA, of the bountiful land.