"Population Growth, Agricultural Intensification, and Culture Change Among the Virgin Branch Anasazi," Journal of Field Archaeology, 22(4) 1-22, 1995.

Abstract Virgin Branch Anasazi settlement pattern data are examined to determine the extent to which agricultural practices may have been intensified along the Muddy and Virgin Rivers between A.D.100 and A.D. 1150. It is argued that as population levels increase among arid land hunters and gatherers there is an inevitable decline in the ratio between the quantities of wild resources and a region's human population. In response to such imbalances a progressive shift towards a greater reliance upon domesticated crops, storage and trade occurs which promotes yet further demographic increases and still greater demands for food production. Analyses of Periods III, IV and V settlement data derived from new intensive archaeological surveys supports the notion that in response to population growth the Virgin Branch Anasazi did intensify agricultural productivity and they did so by means of check dams and ditch canal irrigation. Change reflected in agricultural practices and technologies, storage and social organization are consistent with those predicted. Increases in population size and densities, coupled with a greater dependency upon an agricultural economy within a high risk agricultural environment, were the primary factors driving cultural evolution in this agriculturally marginal setting.

The purpose of this paper is to examine the role of population pressure in producing culture change among the Virgin Branch Anasazi between A.C.100 and A.C.1150. I argue that as populations increased within the constrained environments of the southern Great Basin, there were increased costs and risk associated with a hunting and gathering economy that exceeded the cost output requirements for an agricultural economy and led to a greater dependency upon the latter strategy. Once the Virgin Branch Anasazi became dependent primarily upon an agricultural economy, and as population size and densities continued to increase beyond that which would be economically supported by wild resources alone, the economic shift to an agricultural economy intensified and became irreversible. Patterns of population growth and culture change are developed using data from 163 archaeological sites recorded along the Virgin and Muddy Rivers of southern Nevada. This discussion attempts to inform the reader about a poorly understood group of arid land farmers who occupied the northern frontier of the American Southwest.