Simulated Anasazi Storage Behavior Using Crop Yeilds Reconstructed from Tree Rings: A.D. 652-1968

A clear understanding of interactions between the arid Southwestern environment and that area’s prehistoric inhabitants has been a goal of Southwestern archaeology. This research has reconstructed annual corn and dry bean crop yields for southwestern Colorado from A.D. 650 to 1968, as well as the amounts of those foods available for each of those years. Colorado’s five southwestern county dry farming corn and dry bean crop records were combined to create two regional crop series. Modern technology’s increasing influence was recognized as being present in the two series. This influence was felt to parallel Colorado’s statewide fertilizer consumption and was removed using a multiple regression procedure. Two modern technology free regional crop series resulted. These two series, along with the original two historic crop series were calibrated against five Four Corners tree-ring chronologies from four localities. Both Douglas-fir and pinyon were employed in the calibration. The calibration process used multiple regression so that each series’ current annual crop yield could be predicted using one or more of 25 separate dendrochronological predictors. The regression equation deemed most suitable for predicting each of the four crop series was utilized to reconstruct annual crop yield estimates for the A.D. 652-1968 period. Normal verification was impossible since additional independent crop data were lacking. The reconstructed crop yield series were evaluated statistically. Portions of them were compared against historically recorded events. These two types of testing suggested that the retrodictions were probably valid. The crop yield reconstructions provided the basic data for four sets of storage simulations that attempted to determine corn and dry bean availability for each year from A.D. 652 to 1968, given certain assumptions about the levels of storage technology available to the Anasazi of southwestern Colorado. A. E. Douglass’ A.D. 1276-1299 “Great Drought” appears to be confirmed. A number of additional famines or food crises have also been recognized. In addition, periods when food was super abundant have been identified. It now appears that much of the Four Corners large public construction projects were undertaken during and perhaps because of these periods of excess surplus.