The Domestication of Maize and the Evolution of Agricultural Economies in the Balsas River Valley, Mexico

Temple University, Philadelphia PA

Investigators

Abstract

The goal of this research is to study the evolution of corn or maize (Zea mays L.) and associated agricultural practices by excavating archaeological deposits in caves and rock shelters in the Central Balsas watershed, tropical southwestern Mexico, and carrying out macrofossil (visible remains of seeds and fruits) and microfossil (phytoliths, starch grains, pollen) research on plant remains retrieved from the sediments, stone tools, and pottery. Although maize was long thought to have been domesticated in the arid Mexican highlands, molecular studies of modern varieties of wild and domesticated Zea now indicate that maize was probably domesticated in the Central Balsas River Valley. However, archaeologists have neither carried out searches for, nor excavated, early sites in this region. The absence of archaeological work perhaps explains why, despite years of research, the earliest stages of maize domestication and prior use of its wild ancestor, teosinte, as a food plant have yet be documented. Some of the archaeological sites to be excavated during this phase of the research were located on foot surveys carried out in January of 2003. Artifacts recovered from the site surfaces and from the spoil piles of previously dug pits indicate that the sites were occupied in preceramic times (before ca. 2000 B.C.). Additional foot surveys will also be initiated in the study area to locate more sites for testing that may have been occupied during the early and middle Holocene periods, and possibly earlier (ca. 10,000 to 3000 B.C.). The results of this research have the potential to make an important contribution to the comparative study of the origin and evolution of agriculture in what was one of the world's most important centers of prehistoric plant domestication. The establishment through the proposed research of the sequence of plant manipulation and domestication in this tropical region of Mexico combined with the vegetational and climatic history of the region - determined from our earlier analyses of sediment cores from lakes dating from the last Ice Age (ca. 14,000 years ago) to the modern era - will contribute to an increased awareness of how human populations made profound impacts on the flora and fauna of their landscapes millennia before the modern era. Records such as these are not just of special scholarly interest. Models of ecosystem preservation and restoration rely on empirical data generated by longitudinal studies such as this one. This project also promotes collaboration among scientists from different disciplines (archaeology, paleobotany, and geology) and countries (United States, Mexico, Uruguay and Panama) as well as training of students from different countries (United States, Mexico, Canada and Uruguay).