Measurement of 87Sr/86Sr relative abundance ratios in tooth enamel is a primary method to determine human paleomobility, and a growing number of studies now use these measurements to also reconstruct individual life histories and geographical origins. Here we test the utility and validity of this method for reconstructing individual life histories. To investigate intra-individual variability, we present results from blinded measurements of strontium isotope ratios in 42 tooth enamel samples from seven individuals found at the late prehistoric site of Pampa de los Gentiles, Chincha Valley, Peru. These samples include enamel that formed early in the development of the individual, as well as enamel that formed during adolescence. This allowed us to investigate normal variation in tooth enamel 87Sr/86Sr ratios. Within the same tooth type in the same individual, differences in 87Sr/86Sr ratios from right and left dental elements ranged from below the limit of detection (<0.00000, canine, Individual 23) to 0.00015 (first premolar, Individual 11). Because of the scale of this difference, these results validate the utility of intra-individual studies that focus on enamel that formed at different times during human development. The data also validate the utility of these strontium isotope ratio measurements when made to the third and fourth decimal place for making archaeological meaningful inferences about paleomobility.
Bibliographical noteFunding Information:
We gratefully acknowledge funding from the UCLA Vice Chancellor for Research, the Cotsen Endowments, Mr. Harris Bass, Dr. Bruce Hector, and Mr. Charles Steinmetz, and Henry Tantalean would like to acknowledge Proyecto Prometeo of the Secretaría de Educación Superior, Ciencia, Tecnología e Innovación of the República del Ecuador for its support of this research. All materials were excavated and exported with appropriate permissions from the government of Peru (024-2013-VMCPIC-MC). In Peru, Ms. Kelita Pérez Cubas was an invaluable team member. We also gratefully acknowledge the laboratory assistance of Ms. Annie Laurie Norris, Ms. Emily Schach, and Ms. Emily Sharp in the Archaeological Chemistry Laboratory at Arizona State University and the faculty and staff of the W.M. Keck Foundation Laboratory for Environmental Biogeochemistry at Arizona State University, particularly Drs. Ariel Anbar and Gwyneth Gordon. Editorial assistance of Dr. Hans Barnard (UCLA) is gratefully acknowledged. Finally, we are thankful for the constructive comments from two anonymous reviewers.
- Bone chemistry
- South America