For more than 99 percent of the time since the genus Homo arose two million years ago, everyone lived as hunter-gatherers. Then, once plants and animals were domesticated, the discovery sparked a complete reorganization of the globe. Food production marched in lockstep with greater population densities, which allowed farm-based societies to displace or destroy hunter-gatherer groups. Villages were formed, then cities, then nations. And in a relatively brief period, the hunter-gatherer lifestyle was all but extinguished. Agriculture's sudden rise, however, came with a price. It introduced infectious-disease epidemics, social stratification, intermittent famines, and large-scale war. Jared Diamond, the UCLA professor and writer, has called the adoption of agriculture nothing less than "the worst mistake in human history"—a mistake, he suggests, from which we have never recovered. The Hadza do not engage in warfare. They've never lived densely enough to be seriously threatened by an infectious outbreak. They have no known history of famine; rather, there is evidence of people from a farming group coming to live with them during a time of crop failure. The Hadza diet remains even today more stable and varied than that of most of the world's citizens. They enjoy an extraordinary amount of leisure time. Anthropologists have estimated that they "work"—actively pursue food—four to six hours a day. And over all these thousands of years, they've left hardly more than a footprint on the land.There are no wedding ceremonies. A couple that sleeps at the same fire for a while may eventually refer to themselves as married. Most of the Hadza I met, men and women alike, were serial monogamists, changing spouses every few years. There was a bevy of children in the camp, with the resident grandmother, a tiny, cheerful lady named Nsalu, running a sort of day care while the adults were in the bush. Except for breast-feeding infants, it was hard to determine which kids belonged to which parents. Among the Hadza, women are frequently the ones who initiate a breakup—woe to the man who proves himself an incompetent hunter or treats his wife poorly.While Hadza have a word for body odor, the men tell me that they prefer their women not to bathe—the longer they go between baths, they say, the more attractive they are. Nduku, my Hadza language teacher, said she sometimes waits months between baths, though she can't understand why her husband wants her that way.