In the standard account of human history, agriculture represents the ur-breakthrough. The domestication of plants and animals allowed people for the first time to build up surpluses of food. This, in turn, allowed them to think about something besides feeding themselves. They became merchants and priests and artisans and bookkeepers. They built villages, towns, and cities. Every subsequent innovation—metallurgy, writing, mathematics, science, and even paleo web sites—could be said to owe its origin to those first farmers scratching with sticks in the dirt.