Constraints and innovation

From Mapping Human History: Genes, Race, and Our Common Origins by Steve Olson. Page 98.

Again with the economics. In this case, agriculture arises because of space constraints requiring intensification of productivity for survival.

The first people in the world to domesticate plants and animals were the occupants of towns such as Jericho in the western part of the Middle East. But elsewhere other groups of hunter-gatherers also were beginning to experiment with farming. Between 10,000 and 4,000 years ago, agricultural societies sprang up in eastern and southeastern Asia, New Guinea, Africa, Central America, South America, and eastern North America.

The development of agriculture in so many places within a relatively short period has led to much speculation among archaeologists. One hypothesis was that ancient peoples exchanged ideas through some sort of prehistoric grapevine. This speculation was often applied not just to agriculture but to pottery making, iron smelting, and other technologies as well. Usually it was couched in terms of a superior civilization bestowing the fruits of its culture on a benighted people too ignorant to invent anything for themselves.

But the more closely archaeologists looked at these so-called diffusionist theories, the more unrealistic they seemed. No evidence supports the idea that the various centers of agricultural development communicated with one another. Uninhabitable deserts, impassable oceans, and vast distances separated these regions. If widely separated ancient peoples had been in regular communication with each other, human history would have been quite different.

In the case of agriculture, other forces must have caused its independent development in numerous places around the world. The quest to identify these forces has long attracted scholars of a particularly ambitious cast, many of whom have fallen prey to the desire for simple, concise explanations of exceedingly complex events. They have cited, for example, climate change, population fluctuations, or even the appearance of a solitary genius as the trigger for agriculture.

But the origins of agriculture don't resemble a law of nature at all. Throughout the world, people responded in particular ways to particular circumstances, and their responses resemble something that is much more familiar to us - a narrative. These accounts have plots, characters, settings - all the elements of a good story. And each story is different, which is why it is so hard to come up with a single explanation for the origins of agriculture.

But the stories have common themes, even if they play out differently. One such theme is population growth. In many parts of the world, hunter-gatherer societies expanded in numbers right before the advent of agriculture. In previous millennia, if wild plants and animals became scarce, foraging peoples could simply move. But by 12,000 years ago or so, that option became less viable in many places, because moving meant coming into conflict with other people living off the land. Finding ways to use the land more intensively must have seemed the easier option.