PULLMAN – Using computer simulations to synthesize both new and earlier research, a team of scientists led by a WSU anthropology professor has given new perspective to the question: what happened more than 700 years ago to cause the Pueblo people, Anasazi, to abruptly end their 700-year-long occupation of the cliff dwellings of Mesa Verde and other communities in southwestern Colorado.
 
WSU Regents Professor Tim Kohler and three colleagues describe how computer simulatio
n techniques were used to integrate nearly a century’s worth of archeological research with new climatic, ecological and demographic data to analyze two major cycles in population growth and decline among the ancientAnasazi.The article will be published in an upcoming issue of “American Scientist.”
 
Ultimately their data suggests that the final population collapse resulted from a complex set of environmental changes and societal pressures-including climate change, population growth, increasing competition for resources and escalating conflict and violence among local societies.
 
Mesa Verde National Park was preserved in 1906 by President Theodore Roosevelt. The ancestral Pueblo homeland is also known today as the Four Corners Region of the American Southwest, an area marked by the intersection of Arizona, Colorado, New Mexico and Utah.
 
Archeological evidence has shown that the Anasazi inhabited the region and prospered there from about A.D. 600  until sometime in the late 1200s, when they abandoned their communities abruptly – often within the span of a single generation – and migrated southward.
 
Since the discovery of the Mesa Verde sites in the late 19th century, archaeologists have frequently invoked single factors-such as climate change or conflict – as explanations for the depopulation of more than 600 cliff dwellings in Mesa Verde, as well as the thousands of small residences and large community centers across the Four Corners.
 
More recently, some scholars have even suggested that better conditions or new types of social organization may have drawn the Pueblo people south.
 
In their recent article, however, Kohler and co-authors Mark D. Varien, Vice President of Programs at the Crow Canyon Archaeological Center in Cortez, Colo., Aaron M. Wright, WSU anthropology doctoral candidate and Preservation Fellow at the Center for Desert Archaeology, and Kristin A. Kuckelman, Senior Research Archaeologist at the Crow Canyon center, say their research demonstrates the factors leading to the Anasazi exodus were likely far more complex.
 
“Instead, it was a cascade of events that included climate-induced immigration from peripheral regions resulting in overpopulation, in turn generating resource depletion that was exacerbated by a decline in maize productivity.,” the authors write. “These changes provoked conflict, which in turn induced more scarcity. As these societies began to lose population, they also functioned less successfully and became vulnerable to aggression.”
 
The researchers write, “violence and famine provided potent motives for departure. Evidence suggests that the survivors of these final events moved south, following kin who had pioneered migration streams in that direction at least a century earlier. The societies that they joined and helped build there were substantially different from those they left behind. Perhaps this suggests the degree of trauma that the Pueblo people experienced toward the end in the Four Corners region, and why they never returned to farm the Mesa Verde.”