To science we owe dramatic changes in our smug self-image. Astronomy taught us that our earth isn't the center of the universe but merely one of billions of heavenly bodies. From biology we learned that we weren't specially created by God but evolved along with millions of other species. Now archaeology is demolishing another sacred belief: that human history over the past million years has been a long tale of progress. In particular, recent discoveries suggest that the adoption of agriculture, supposedly our most decisive step toward a better life, was in many ways a catastrophe from which we have never recovered. With agriculture came the gross social and sexual inequality, the disease and despotism, that curse our existence. At first, the evidence against this revisionist interpretation will strike twentieth century Americans as irrefutable. We're better off in almost every respect than people of the Middle Ages, who in turn had it easier than cavemen, who in turn were better off than apes. Just count our advantages. We enjoy the most abundant and varied foods, the best tools and material goods, some of the longest and healthiest lives, in history. Most of us are safe from starvation and predators. We get our energy from oil and machines, not from our sweat. What neo-Luddite among us would trade his life for that of a medieval peasant, a caveman, or an ape?
For most of our history we supported ourselves by hunting and gathering: we hunted wild animals and foraged for wild plants. It's a life that philosophers have traditionally regarded as nasty, brutish, and short. Since no food is grown and little is stored, there is (in this view) no respite from the struggle that starts anew each day to find wild foods and avoid starving. Our escape from this misery was facilitated only 10,000 years ago, when in different parts of the world people began to domesticate plants and animals. The agricultural revolution spread until today it's nearly universal and few tribes of hunter-gatherers survive.
From the progressivist perspective on which I was brought up, to ask "Why did almost all our hunter-gatherer ancestors adopt agriculture?" is silly. Of course they adopted it because agriculture is an efficient way to get more food for less work. Planted crops yield far more tons per acre than roots and berries. Just imagine a band of savages, exhausted from searching for nuts or chasing wild animals, suddenly grazing for the first time at a fruit-laden orchard or a pasture full of sheep. How many milliseconds do you think it would take them to appreciate the advantages of agriculture?