Thousands of years ago, our ancestors gave up foraging for food and took up farming, one of the most important and debated decisions in history.

Was farming more efficient than foraging? Did the easily hunted animals die out? Did the environment change?

A new study by Samuel Bowles of the Santa Fe Institute in New Mexico argues that early farming was not more productive than foraging, but people took it up for social and demographic reasons.

In Monday's edition of Proceedings of the National Academy of Sciences, Bowles analyzed what it would take to farm under primitive conditions. He concluded farming produced only about three-fifths of the food gained from foraging.

But, Bowles notes, farming became the most common way of living between 10,000 and 5,000 years ago because of its contribution to population growth and military power.

Without the need for constant movement, child-rearing would have been easier and safer, leading to a population increase, Bowles said. And since stored grain might be looted, farmer communities could have banded together for defense and would have eventually pushed out neighboring foragers, he suggests.

Brian Fagan, a professor emeritus of archaeology at the University of California, Santa Barbara, called Bowles' ideas "provocative and fascinating."

It had been suspected that the earliest farming was not necessarily more productive, said Fagan, who was not part of the research.

"What he does is to draw attention to the social and demographic factors that contributed so importantly to the spread of farming," Fagan said. "This is a useful contribution to a debate about agricultural origins that has been under way for generations."

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