Meanwhile, Kohler and his colleagues are examining the role of factors like maize production, changes to the climate, and growing population in changing levels of violence. A paper of his published in June in the Proceedings of the National Academy of Sciences found that the Southwest had a baby boom between 500 and 1300 that likely exceeded any population spurt on earth today.
Both the central Mesa Verde and northern Rio Grande experienced population booms, said Kohler, but surprisingly, the central Mesa Verde got more violent while the northern Rio Grande grew less so.
Kohler offers a few explanations.
Social structures among people in the northern Rio Grande changed so that they identified less with their kin and more with the larger pueblo and specific organizations that span many pueblos, such as medicine societies. The Rio Grande also had more commercial exchanges where craft specialists provided people both in the pueblo, and outsiders, specific things they needed, such as obsidian arrow points.
But in the central Mesa Verde, there was less specialization.
"When you don't have specialization in societies, there's a sense in which everybody is a competitor because everybody is doing the same thing," said Kohler. But with specialization, people are more dependent on each other and more reluctant to do harm.
Kohler and his colleagues also cite Harvard psychologist Steven Pinker's thinking in his book, The Better Angels of Our Nature: Why Violence Has Declined.
"Pinker thought that what he called 'gentle commerce' was very important in the pacification of the world over the last 5,000 years," said Kohler. "That seems to work pretty well in our record as well."
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|Contact: Tim Kohler|
Washington State University