Anasazi harvests: Agroclimate, harvest variability, and agricultural strategies on prehistoric Black Mesa, northeastern Arizona

Prehistoric farmers in the American Southwest sustained corn yields in an unpredictable agricultural environment. The stability of small primitive farming communities and the potential for agricultural intensification in this area have been questioned for some time. This research examines the variability in corn harvests and the dependability of the corn diet during the Anasazi occupation of Black Mesa in northeastern Arizona.;The prehistoric agroclimate, climatic variables critical to corn growth and development, is reconstructed from a surrogate tree-ring chronology for Black Mesa. Annual variability in radial tree growth is calibrated to a prepared historic climatic series. Annual precipitation and summer temperatures are predicted for the period from A.D. 700 to 1300.;Corn harvests in the Southwest rise or fall as the climate for agriculture improves or deteriorates. A schedule of corn growth and development is designed to identify critical climatic variables. Reductions in corn yields are estimated from summer rainfall deficits for the period from A.D. 700 to 1300. A Hopi ethnographic model of farming strategies is used to simulate the volume of corn harvested, stored, and consumed over time.;Predictions for increasing variety in meals and increasing settlement mobility linked to the uncertainty of corn harvests are tested against the archaeological record. Prior dietary studies demonstrate the variety of Black Mesa meals, but fail to confirm increased reliance on non-cultigens over time. Changes in occupation span are evaluated during periods of critical food shortages.;Results of this research challenge the accepted view of the instability of prehistoric corn farming in the Southwest. The amount of acreage under cultivation and stored corn reserves temper annual reductions in corn yields to provide a dependable food supply. Anasazi communities on Black Mesa increased settlement mobility during the most severe droughts, but were sufficiently productive in better years that they were able to store enough corn to withstand periodic crop shortfalls. The demonstrated variability in corn harvests raises new questions about the potential for and the social and demographic consequences of agricultural intensification in the Southwest.