<\/p>\n
Time and again, drought was the final straw that disrupted complex ancestral Puebloan societies in the Southwest and shifted the cultures, according to a new study.<\/p>\n
\u201cThose societies took a long time to build and a very short time to collapse,\u201d said Washington State University anthropologist R. Kyle Bocinsky, one of the study\u2019s lead authors. \u201cWe think those collapses were tied to slightly worse-than-normal climate challenges that undermined leadership and social consensus.\u201d<\/p>\n
Pueblos and villages around Mesa Verde rose to prominence beginning in A.D. 1145. By 1285, they were completely abandoned, following several years of drought, in one of the great mysteries of the Southwest.<\/p>\n
But a similar rise and fall among ancient pueblos had happened three times in the previous 900 years, Bocinsky and three other researchers said in their report, \u201cExploration and exploitation in the macrohistory of the pre-Hispanic Pueblo Southwest,\u201d published April 1, in the journal Science Advances.<\/p>\n
The Chaco civilization grew into a major trading and ceremonial center from A.D. 890 to the mid-1100s. By 1145, it was over.<\/p>\n
A similar occurrence happened among pueblos from A.D. 700 to 890 and again during the Basketmaker III era, between A.D. 500 and 700. Each time, the Pueblo people dispersed, looked for new places to farm, came together and reinvented their societies.<\/p>\n
Drought alone didn\u2019t cause the societies to collapse, said Bocinsky, who is now director of sponsored projects at Crow Canyon Archaeological Center in Cortez.<\/p>\n
But when their corn harvests were slim even though they had performed ceremonies correctly, people stopped believing in their leaders, and the social fabric cracked.<\/p>\n
Timothy A. Kohler, another of the study\u2019s authors, said the ancestral Puebloan societies were \u201cwoven together with a web of ceremony and ritual that required belief in the supernatural\u201d to ensure plentiful rain and good crops.<\/p>\n
When rains failed to appear, he said, the rituals lost legitimacy. \u201cThen there\u2019s a point where people say, \u2018This isn\u2019t working. We\u2019re leaving,\u2019 \u201d said Kohler, an archaeologist and external faculty member with the Santa Fe Institute.<\/p>\n
Bocinsky, Kohler and two other scientists analyzed data from 1,002 distinct archaeological sites and nearly 30,000 tree-ring samples from across the Four Corners region using supercomputers. It was the first such attempt to use a massive amount of data points to construct a look at where people grew corn and how that influenced migrations across the landscapes.<\/p>\n
The tree-ring data from ancient forests and from timber used in ancestral Puebloan structures helped the scientists figure out where and when ancestral people were growing maize and constructing buildings. The data also showed them exactly where and when drought was happening across the landscape.<\/p>\n
Each major rise, collapse and shift of ancestral Puebloan societies followed a similar pattern, Bocinksy said. Ancestral Puebloan people looked for new places to grow maize, watered from streams and rain. Independent farmers and families joined into larger villages. They agreed on ways to store food, on ceremonies and on how to conduct themselves socially.<\/p>\n
The more complex societies, like those at Chaco Canyon and Mesa Verde, were the least equal. Evidence at the ancient sites show some people lived in a version of McMansions, while others lived in small rooms. \u201cWe see differences in terms of burial, room sizes, diet,\u201d Bocinksy said.<\/p>\n
\u201cWe see this rising inequality that arrives at a crescendo. Then when the society falls, we see a shift to more equality,\u201d he said.<\/p>\n
Kohler agreed. \u201cAfter the Pueblo I collapsed around (A.D. 900), people in a sense voted for hierarchy. They said, \u2018Let\u2019s go with Chaco, the most hierarchical, most socially stratified, for Pueblo culture.\u2019 It didn\u2019t work, but they tried again with Mesa Verde. When that didn\u2019t work, they rejected hierarchy completely.\u201d<\/p>\n
\u201cThe biggest change we see in Pueblo history is the abandonment of Mesa Verde and the Four Corners,\u201d Kohler said.<\/p>\n
Archaeologists believe the people from Mesa Verde migrated to pueblos along the Northern Rio Grande. These pueblos, some enduring today, have houses that open onto a central plaza, where everyone can see and in some way participate in the religious ceremonies, Bocinksy said.<\/p>\n
\u201cThey went from a situation where certain people had access to important rituals to one where there was a more equal access,\u201d he said. \u201cThat\u2019s a big change.\u201d<\/p>\n
Bocinsky sees the same seeds of discontent that prompted pueblos to change their societies playing out in this year\u2019s raucous and surprising presidential election.<\/p>\n
\u201cA lot of people still haven\u2019t recovered from the 2008 economic downturn, and we\u2019ve seen a lot of growth in inequality in the last eight years. That\u2019s undermined the credibility of the system,\u201d Bocinsky theorizes. \u201cSupport for Trump and Sanders represents that discontent.\u201d<\/p>\n
Bocinksy said leaders and policymakers in the Southwest need to consider \u201cthe pernicious nature of inequality, combined with climate change, to destabilize societies.\u201d<\/p>\n
It\u2019s happened before.<\/p>\n
Bocinsky and Kohler collaborated on their paper with Jonathan Rush of the National Center for Super Computing Applications at the University of Illinois at Urbana-Champaign and Keith Kintigh of the School of Human Evolution and Social Change at Arizona State University.<\/p>\n