Doctoral Dissertation Improvement Grant: Detection and Identification of Maize in Absorbed Pottery Residues: Development and Application

Harvard University, Cambridge MA

Investigators

Abstract

Under the direction of Dr. Nikolaas van der Merwe, MS Eleanora Reber will collect data for her doctoral dissertation. The goal of her research is to develop a technique to determine whether maize was consumed at specific prehistoric sites. Maize was domesticated in highland Mexico and spread through large portions of both North and South America. Today it is widely planted in both the Old and New Worlds and is the second largest harvested crop (after sugar cane). Because of the yield in relation to labor and its relative dependability maize provided the subsistence base from which complex society arose throughout much of the New World. Archaeologists believe that it was the development of maize-based agriculture which underlies the early cultural explosions in the US Southwest, Midwest and Southeast. However because floral remains are poorly preserved in most archaeological sites, often evidence for maize is indirect and scientists have been forced to rely, for example, on subtle chemical signatures in human bone. MS Reber is developing a technique with the potential to identify maize residue on cooking pots. Ethnographic evidence suggests that Native Americans boiled corn for extended periods in ceramic vessels and because clay is porous it has the potential to absorb food residue. MS Reber will utilize both a gas chromatograph/mass spectrometer and gas chromatograph-combustion-mass spectrometry to analyze chemical residue extracted from ceramics to search for a maize signal. Specific chemical compounds will be identified and the carbon isotope ratios of each determined. In many areas of the world maize has a distinctive isotopic signature in relation to other plants and it is this which shall provide the distinctive clue. MS Reber will first conduct controlled experiments in which a traditional variety of Native American maize is cooked in ceramic vessels. These will then be buried in soil for varying lengths of time to approximate archaeological situations. Residues will then be extracted and analyzed. On the basis of these results, the process will be fine-tuned and then applied to archaeological specimens. Finally MS Reber will apply the technique to a specific archaeological question. At approximately the time that complex society arose in the American Midwest, a shift in pottery types took place and thin walled vessels replaced their thick walled counterparts. Archaeologists have postulated that this change coincides with the introduction of maize and that thin walled vessels were more efficient for preparing corn stews. Through analysis of both thick and thin walled vessels, MS Reber will evaluate this hypothesis. This research is important for several reasons. It will help to develop a technique which, if successful, will be applicable in many archaeological sites in many regions of the world. The work will provide insight into the prehistory of the United States and will assist in training a promising young scientist.