Bioarchaeological and Forensic Applications of Oxygen and Strontium Isoscape Methods

Scaffidi Cassandra K, Nashville TN

Investigators

Abstract

This award was provided as part of NSF's Social, Behavioral and Economic Sciences Postdoctoral Research Fellowships (SPRF) program. The goal of the SPRF program is to prepare promising, early career doctoral-level scientists for scientific careers in academia, industry or private sector, and government. SPRF awards involve two years of training under the sponsorship of established scientists and encourage Postdoctoral Fellows to perform independent research. NSF seeks to promote the participation of scientists from all segments of the scientific community, including those from underrepresented groups, in its research programs and activities; the postdoctoral period is considered to be an important level of professional development in attaining this goal. Each Postdoctoral Fellow must address important scientific questions that advance their respective disciplinary fields. Under the sponsorship of Dr. Kelly Knudson at Arizona State University, this postdoctoral fellowship award supports an early career scientist investigating how spatial variation in stable and radiogenic isotopes throughout complex hydrological systems can be used to "geo-locate" or assign human or animal individuals of unknown geographic origin to specific places of origin along an isotopic landscape or "isoscape" Mammalian tissues record the signature of oxygen and strontium isotopes from the food, water, and air consumed during the period of development. Comparing oxygen and strontium tissue values enables the identification of outlier individuals, or first-generation migrant. However, to match migrants to their places of origin, it is first necessary to develop predictive, spatially-explicit isotope models of oxygen and strontium values throughout a study region. This project will systematically collect samples of water, soil, plants, and animals from ten major river valleys, analyze these materials to establish isotopic baseline values, and generate predictive dual-isotope and single-isotope models. Human archaeological values will then be matched to their most likely place of origin using probabilistic statistical methods. This project, conducted with the Archaeological Chemistry Laboratory of the Center for Bioarchaeological Research and the W. M. Keck Foundation Laboratory for Environmental Biogeochemistry at Arizona State University, analyzes biogeochemical variation in order to generate predictive isotope models for the probabilistic determination of provenience and isotopic life histories. The Fellow will carry out dry and wet season sampling campaigns, systematically collecting environmental samples of water, soil, plants, and fauna from regular altitudinal intervals. Samples from 100 control points will be re-sampled in the wet and dry season to understand the impact of seasonal weather patterns on isotope values. Archaeological applications of these methods can be used to trace ancient migration and trade networks between specific locations, or to identify the isotopic provenience of important people or artifacts. Importantly, this project will also establish a database, which will be a collaborative, cloud-based application for collecting and sharing isotope baseline data before and after publication. The field collection side of the database will be critical in standardizing the collection of baseline data, which will allow the scientific community to explore the relationships between landscape conditions and isotope values. The data-sharing side of the database will allow professionals and scientists access to isotope data and isoscape models, which will provide a tool for helping forensic and other researchers to pinpoint likely origins for individuals. These data and methods will serve as the foundation for geostatistically robust baseline maps, which can be used by anthropologists to understand human responses to environmental and cultural change, by ecologists or biologists working with these species, or by researchers investigating similar questions throughout the world. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.