Isotopic Studies of Human Movement in the Prehistoric American Southwest

University Of Wisconsin-Madison, Madison WI

Investigators

Abstract

NSF funding will be used for the study of human mobility in the prehistoric Southwestern United States. This area witnessed millennia of migration and movement for various reasons, including colonization, conflict, and climate change. Many questions regarding mobility in this area remain difficult to answer, however, in part because archaeological methods have focused on artifacts and architecture as proxies for people. Things and ideas can be borrowed, stolen, or traded. A new method in archaeology involving the analysis of isotopes in human tooth enamel, however, provides a direct measure of movement. Prof. T. Douglas Price and colleagues will use isotopes of strontium, oxygen, and carbon in tooth enamel to directly investigate human movement, building on a successful earlier study at Grasshopper Pueblo, Arizona. The principle of the method is straightforward and well documented. Enamel forms in early childhood and incorporates the isotopic ratio of the place of birth. Enamel is inert and resistant to contamination and decomposition, thus providing an isotopic signature of place of birth. This signature is retained after death and often after burial. Because the isotopic signal in bone is continually updated during life it reflects recent residence. If the isotopic signal of the place of death is different from the enamel, the individual must have moved to a different geological location during his/her lifetime. Carbon isotopes reflect diet. A pilot study of 32 teeth from 3 sites in three different areas documents significant variability and the presence of non-locals. Related projects will measure carbon and nitrogen isotopes in bone for paleodiet and ancient DNA for genetic relationships in the same individuals. Samples will be shared among the research groups to reduce the impact on collections. The three study areas for this project, and some of the important research questions, are 1. The introduction of agriculture into Four Corners region, and relationships between Eastern and Western Basketmaker cultures. 2. Human movement and interaction in Chaco Canyon and northwestern New Mexico where isotope studies of timber, maize, and deer have documented long-distance transport. Fascinating questions concern the origin, nature, and causes for this phenomenon. The relationship between the Chaco Great Houses and their satellite communities remain one of the more intriguing mysteries in American archaeology. Research will focus on the humans at Pueblo Bonito and other Great House pueblos where evidence from burial practices suggests social inequality. Samples from outlier communities will be included for comparison. 3. Investigation of the Mimbres culture of southwestern New Mexico will focus on the relationship between Mimbres and Hohokam and Mogollon groups in the ancient Southwest. There are also indications of ties with the large, regional center of Casas Grandes, some 200 km to the south in northern Mexico. A more general question concerns the movement of Uto-Aztecan groups from Central Mexico into the Southwest and their relationship with indigenous populations. Isotopic analysis of human tooth enamel from these three areas should provide substantial insight into many of these questions. This research will help us understand the nature and extent of human movement during the last 2000 years or so of prehistory in the American Southwest.