In, "The Planet of No Return," Erle Ellis contends that "hunting-and-gathering was not displaced for lack of wild animals and foods, but due to the superiority of agriculture."

I disagree. Ellis's view of the rise of agriculture is a classic myth that has been propagated by non-archaeologists for generations -- the "better mousetrap" theory of agriculture. My own archaeological research suggests the opposite.

Take the commitment to agriculture in North America. We have good evidence that maize arrived in the American Southwest about 3,800 years ago. Yet, in the archaeological record, we do not see the sustained development of maize-based communities until about 1,500 years ago. If agriculture was so much better than hunting-and-gathering (H&G), what was everybody doing in the intervening 2,300 years?

From an energy standpoint, it has been demonstrated that hunting-and-gathering is a more efficient lifestyle than agriculture. So the question becomes, "Why would people adopt agriculture at all?" Long-story-short: a downturn in access to gathered seed resources. Easily stored resources such as seeds were important to H&G groups as part of their overwintering strategy. When downturns in climate (decreased precipitation) reduced the productivity of native seed resources, H&G groups could fall back on domesticated plants (agriculture) to fill the gap. As the archaeological record shows, upturns in precipitation saw short-term horticultural efforts abandoned.

By 1,500 years ago, demographic packing -- too many people on the landscape -- became an issue. Horticulturalists were compelled to keep farming even when rainfall increased, as there was no place left to forage. So, people didn't farm because they wanted to, they did it because they had to. Worldwide there are other examples of farmers abandoning farming to become hunters and gatherers once their access to wild resources improved. The farming Hidatsa Indians dropped their hoes and became bison hunters upon the arrival of the horse. Once the Hidasta were able to increase their access to wild resources, hunting simply trumped farming.