A new computer simulation of the changing environmental conditions around one of the Anasazi cultural centers early in the past millennium suggest that drought was not the only factor behind a sudden collapse of the civilization.
Northeastern Arizona's Long House Valley was home to the Kayenta Anasazi, one of several branches of a complex culture that disappeared from the American Southwest in the 12th century. Anasazi were subsistence farmers who grew maize, beans, and squash. The rich archaeological record in the 96-square-kilometer valley, along with a wealth of data about environmental conditions there, enables scientists to construct detailed computer models of population growth in the valley, says George J. Gumerman, director of the Arizona State Museum in Tucson.
The simulation uses data about climate from tree rings, pollen in geologic sediments, and soil erosion in Long House Valley to estimate crop yields for each hectare--an area about 2.5 times the size of a football field--from A. …