Book excerpt: During virtually the entire four-million-year history of our habitation on this planet, humans have been hunters and gatherers, dependent for nourishment on the availability of wild plants and animals. Beginning about 10,000 years ago, however, the most remarkable phenomenon in the course of human prehistory was set in motion. At locations around the world, over a period of about 5,000 years, hunters became farmers. Far more than the domestication of plant and animal species was involved in this revolution, which was accompanied by massive changes in the structure and organization of the societies that adopted agriculture and by a totally new relationship with the environment. Whereas hunter-gatherers live off the land in an extensive fashion, exploiting a diversity of resources over a broad area, farmers utilize the landscape intensively. The implications of these changes in human activity and social organization reverberate down to the present day.