Dissertation: The Temporal Resolution of Oxygen and Carbon Stable Isotope Measurements in Tooth Enamel

George Washington University, Washington DC

Investigators

Abstract

This doctoral dissertation research project will permit MS Felicitas Wiedermann to conduct a three stage research project to develop an effective protocol to extract climatic information from tooth enamel. Enamel is a dense, low porosity structure which is well preserved in many archaeological situations and is resistant to contamination from burial environment. Because the oxygen and carbon in the organic component of enamel ultimately derives from food and water consumed by the individual (and its mother) they closely reflect the isotopic ratio of the materials from which these derive. The oxygen isotope ratio of both freestanding and food-incorporated water is affected by both temperature and amount of rainfall and these climatic variables are thus reflected in tooth enamel. Carbon isotope ratio varies with the type of plants an animal consumes and enamel carbon ratios provide insight into vegetation cover. Sheep teeth, which constitute the basis for this study grow in increments and through analysis of the individual sections one can examine the degree of seasonal change across the year. Such knowledge provides an environmental context for understanding prehistoric human behavior. In a multistage study MS Wiedermann hopes to develop a robust analytic methodology. In the first stage she will feed laboratory sheep isotopically labeled water as well as timed biogenic markers which will permit her to determine the rate and geometry of tooth growth. With this information she will develop a strategy for sectioning teeth to remove chronologically relevant samples. She will then apply this technique to modern teeth from the Near East. Since the materials will be obtained from specific locales where vegetation, temperature and vegetation are known it will be possible to draw tight links between isotope ratios and these environmental variables. Finally she will apply the technique to samples from the Neolithic archaeological site of Ain Ghazal, Jordan. This will allow her to determine the extent to which such ancient teeth are subject to in ground alteration and to apply the technique directly to a significant archaeological question. This work is important because, if successful, it will develop a technique which will provide valuable data to prehistorians and other scientists who reconstruct the past. I will also help to train a very promising young scientist.