Climate problems alone were not enough to end periods of ancient Pueblo development in the southwestern United States.

The findings, detailed in an article in the Proceedings of the National Academy of Sciences, showed that Pueblo farmers often persevered through droughts, but when social tensions were increasing, even modest droughts could spell the end of an era of development.

Tim Kohler

“Societies that are cohesive can often find ways to overcome climate challenges,” said Tim Kohler, a Washington State University archeologist and corresponding author on the study. “But societies that are riven by internal social dynamics of any sort—which could be wealth differences, racial disparities or other divisions—are fragile because of those factors. Then climate challenges can easily become very serious.”

Social fragility was not at play, however, at the end of the Pueblo III period in the late 1200s when Pueblo farmers left the Four Corners with most moving far south. This study supports the theory that it was a combination of drought and conflict with outside groups that spurred the Pueblo peoples to leave.

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