While humans evolved 125,000 years ago and had spread to six of the continents by 15-20,000 years ago, we did not establish towns and cities until the end of the Pleistocene Ice Age. Prior to that time, humans were nomadic, living in small clans and moving about in the pursuit of game and other food sources. Indeed, it was the hunting of migratory mammals such as bison and reindeer that primarily led man across the globe.
At the dawn of the Holocene, 10,000 years ago, man began to establish settlements in the Fertile Crescent of the Middle East; this cultural shift soon spread throughout the Mediterranean region and across the southern rim of Asia. Though dogs had been domesticated 2000 years earlier, goats were the first animals raised for food, milk and hides; this occured in the Middle East about 10,000 years ago while pigs and sheep were domesticated in Syria 1000 years later. Cattle were brought under human control 8000 years ago, in western Asia and northern Africa, and chickens were domesticated in Southeast Asia about the same time. Among the earliest crops were peas, barley and wheat, first cultivated in the Middle East 10,000 years ago. As these cultures fluorished and trade lines developed, man domesticated the horse (6000 years ago, in central Asia), the donkey and the camel; the latter two beasts of burden were domesticated in northern Africa and Arabia about 5500 years ago. Finally, ducks were domesticated in Southeast Asia, 5000 years ago.
The same advances were occuring in the Americas during this time. Squash was cultivated in Mexico 10,000 years ago, followed by maize, 6300 years ago, and sunflowers, 4500 years ago. Caral, Peru, established 4600 years ago, is the oldest known city in the Americas; residents of that region grew giant pumpkins and raised guinea pigs. It's truly amazing to realize how much change (good and bad) man has produced over the past 10,000 years, a mere instant in the course of Earth's history.
