Strontium Isotope Analysis, the Neonatal Line, and Archaeological Caribou Herd Identity in Northwest Alaska

Abstract

Rangifer tarandus is a keystone species in the Arctic and has shaped human land use in this region for tens of thousands of years. The migratory ecotype requires large landscapes and long migrations between summer and winter ranges to meet their nutritional needs. The extent to which these ranges have remained the same has been controversial and uncertain. Archaeological caribou herd identity is usually ascribed based on modern caribou herd distribution. However, no study has assessed the validity of the implicit assumption of multi-thousand years of range stasis. Given that a caribou herd’s distribution and landscape use may change in response to ecological or climatic changes, it is important to assess whether past and present calving ground locations may have shifted. In this study, we applied strontium isotope analysis to identify calving grounds of archaeological caribou from the pre-contact/historic Lake Kaiyak site (MIS-00032) near the calving grounds of the modern Western Arctic caribou herd (WAH). We found that the 87Sr/86Sr values of the molars were consistent with those predicted for WAH ranges. The dental enamel from the neonatal line (NNL), a pathological marker of birth, was consistent with the modern WAH calving grounds and early summer range. These results suggest that the archaeological specimens were WAH animals. Broadly, this supports the use of strontium isotope analysis of permanent molars with an emphasis on the NNL to determine the herd identity of ungulates in the archaeological record, which has important implications for archaeology and modern wild ungulate herd management.