H and O isotopes in bone and tooth protein for paleoenvironmental reconstruction

The study of past environments is an important focus for several disciplines, including archaeology. This research develops analytical tools to reconstruct paleoenvironments using molecular-based techniques; specifically, understanding the strengths and limitations of the analysis of hydrogen and oxygen isotopes from the protein in animal bones. Hydrogen and oxygen isotope ratios in the earth’s surface water vary with environmental parameters like temperature and aridity; subsequently these atoms are incorporated into animal tissues through food and water intake, and to some degree can be used as tracers of those original environmental variables. The advantages of understanding the systematics of hydrogen and oxygen isotopic records in animal bones include providing local environmental information at sites with direct human use; the integration of up to five isotope ratios (hydrogen, oxygen, carbon, nitrogen, sulfur), radiocarbon ages, and protein-based species identification; and the ability to use legacy collections and fragmentary bone samples where other materials like teeth are rare. This approach can be applied at archaeological and paleontological sites anywhere worldwide where protein is preserved in bones. Overall this work supports and complements more traditional archaeological approaches to understand the past. This research is conducted in and supports the infrastructure of the Stable Isotope Laboratory at Boise State University, a university facility serving the geosciences, archaeology, and biology. Outreach activities include participation in a campus science and engineering open day and science outreach with young tribal members. This project has three main components. First, assesses how hydrogen and oxygen isotopes in bone protein (collagen) of medium/large mammals change over time at long-duration cave sites and their utility for paleoenvironmental reconstruction, including integration with carbon and nitrogen isotopes and newly-generated radiocarbon dates. Second, furthers the use of peptide mass fingerprinting (ZooMS/MALDI-TOF) to identify the animal species of fragmentary bone material. Third, testing how these protein-based isotopic approaches compare to oxygen and carbon isotopic work on inorganic hard tissues like tooth enamel, which then allows comparison of old and new data sets. This project also investigate sites that range in age over the last few thousands of years and assesses multi-isotopic change over time. Sequential samples of modern faunal teeth are studied to generate comparisons between the organic protein-based and inorganic isotope records.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.