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People of the Colorado Plateau
Paleoindian and Archaic Peoples
Archaeological Treasures
Prehistoric Farmers
Population Change
The Anasazi "collapse"
Pueblo Peoples
Western Apache
Navajo (Diné)
Southern Paiute
Spanish Exploration
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Anglo Settlement

peoplebutton.gif (1940 bytes)Population Change

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Sun petrogylph on Navajo sandstone boulder. Photo © 1999 Ray Wheeler

Throughout their 2000-year history on the Colorado Plateau, Anasazi populations tended to cycle between periods of clustering and dispersal, occupation and abandonment. Yet the period of 700-1130 A.D. was singular for all the various peoples of the Southwest. Technological and social innovations such as pottery for boiling foods, food-sharing and storage, together with a more settled way of life dependent on agriculture, coincided with a period of adequate rainfall. The result was a rapid increase in population.

Skeletal studies show that increases in fertility, not a decrease in mortality, were responsible for the sudden rise in populations. Over several decades, numbers increased dramatically and the Anasazi spread across the landscape. By approximately 1075-1100 A.D., people were more densely packed and widely distributed in the Southwest than ever before, a peak of population not reached again until historic times.

On Black Mesa as in many northern locations, with the exception of a brief interval from about 1030 to 1050 A.D., the density of people increased 10-fold over the course of a few generations. Indigenous population growth alone cannot account for it; significant numbers of people must have moved into the area from the surrounding countryside. Mesa tops were not alone in attracting population growth; in Grand Canyon, during the last half of the eleventh century, communities were established in scores of locations deep within the canyon.

The outposts of the Anasazi realm expanded to the edges of the Colorado Plateau and beyond. Anasazi settlements ranged west to central Utah and the Virgin river, south to the Mogollon Rim in Arizona, and east to the Rio Grande Valley in New Mexico. This demographic shift anticipated the urbanization of the United States during the twentieth century, but on a much smaller scale.

Success, however, may well have been the seed of eventual decline. A severe drought began in 1130 and lasting for 50 years. At the same time another much longer cycle unrelated to precipitation was causing water tables to drop and initiating a period of arroyo-cutting. Anasazi settlements that were on the edges of the realm, or those closer in but inhabititing poor farmland, were the first to be abandoned and left in ruins. By late in the twelfth century many localities on the more arid western extent of the Pueblo homeland were deserted.

Follow these links to:
The Anasazi "collapse"

Adler, M. A. 1994. Population aggregation and the Anasazi social landscape: A view from the Four Corners. Pp. 85-101 In: Wills, W. H. and Leonard, R., editors. The Ancient Southwestern Community: Models and Methods for the Study of Prehistoric Social Organization. University of New Mexico Press, Albuquerque.

Gregory, D. 1999. Perspectives on early agricultural period population size and sedentism. Archaeology Southwest 13: 14-15.

Hack, J. T. 1942. The changing physical environment of the Hopi Indians of Arizona. XXXV; No. 1. Harvard University, Cambridge, MA, 100 pp.

Jett, S. C. 1964. Pueblo Indian migrations: An evaluation of the possible physical and cultural determinants. American Antiquity 29: 281-300.

Kohler, T. A. 1992. Prehistoric human impact on the environment in upland North American southwest. Population and Environment. 13: 255–268.

Lekson, S. H. 1995. Tracking the movements of an ancient people. Archaeology Magazine, Archaeological Institute of America 48: 54-57.

Lipe, W. D. 1995. The depopulation of the northern San Juan: Conditions in the turbulent 1200s. Journal of Anthropological Archaeology 14: 143-169.

Petersen, K. L. 1988. Climate and the Dolores River Anasazi: A Paleoenvironmental Reconstruction from a 10,000-Year Pollen Record, La Plata Mountains, Southwestern Colorado. University of Utah Press, Salt Lake City.

Vivian, R. G. 1990. The Chacoan Prehistory of the San Juan Basin. Academic Press, San Diego, CA.