Kitty Roberts: Optimal Foraging Theory and Production in the Ancient Mississippi Valley

Traditionally, archaeologists assumed that the prehistoric inhabitants of the Lower Mississippi Valley were among the first people to practice maize-based agriculture in what is now the eastern United States and were committed farmers of a group of plants called the native starchy seed plants. With the advent and broad application of flotation recovery and scientific study of plant remains in the region, however, these assumptions have been proven wrong. In the Tensas Basin of the Lower Mississppi Valley, my academic advisor, Gayle Fritz, and I have demonstrated that food surplus, although probably a key component of local subsistence economies, did not derive from agriculture, or horticulture, and definitely not from maize cultivation during the time periods of Coles Creek (A.D. 700-900) and early Misissippi (A.D. 1200-1400). After this pattern became evident, I became interested why this region was so different from that of the mid-latitudes.

I chose optimal foraging theory as the source of my hypotheses about these differences; the main tenet derived from this theory was that foraging and farming activity was aimed at the highest caloric payoff. Analysis of flotation-derived collections from the Tensas suggests that this sort of behavior was in operation during Coles Creek and early Mississipi periods in the Tensas Basin. This argument is supported by the early, and continued focus on high-yielding nuts and fruit, and a later increased importance of maize in the region.

This research suggests that the more extensive use of the native starchy seeds further north may be due to the differences in seasonal availability of food between the Lower Mississippi Valley and the midlatitudes and the importance of these taxa as a stored resource. Further, the results of this work imply that continued and critical use of optimal foraging theory, used in order to discern some of the underlying principles of prehistoric foraging and farming behavior in different ecological environments, is productive and promising, especially when used in together with other sorts of explanations.

PHOTO CAPTIONS. TOP: Scanning electron micrograph of a striate-papillose coated Polygonum erectum seed recovered from an elite refuse context at a multi-mound site in Northeast Louisiana.. BOTTOM: Scanning electron micrograph of a thick-coated Chenopodium berlandieri seed found in an elite refuse context at a multi-mound site in Northeast Louisiana.