Crooked Teeth? Blame Early Farmers

When humans turned from hunting and gathering to farming some 10,000 years ago, they set our species on the road to civilization. Agricultural surpluses led to division of labor, the rise of cities, and technological innovation. But civilization has had both its blessings and its curses. One downside of farming, a new study demonstrates, was a shortening of the human jaw that has left precious little room for our teeth and sends many of us to an orthodontist's chair.

Although all living humans belong to one species, Homo sapiens, there are recognizable differences in the shapes of our skulls and faces across the world. In recent years, anthropologists have concluded that most of this geographic variation in skull shape is due to chance, so-called genetic drift, rather than natural selection. But some features of our faces, including the shape of our lower jaws, don't seem to follow this random pattern....