Reconstructing the origins of the Perrins Ledge cremains using strontium isotope analysis

Abstract

Strontium isotope (87Sr/86Sr) analyses have been used effectively to reconstruct the origin of osteological remains that have not been exposed to increasing temperatures. However, previous research has shown that no thermally induced changes occur to original strontium isotope values (87Sr/86Sr) of bone and tooth specimens that have been subjected to temperatures between 100 and 1000 degrees Celsius, though the published literature regarding strontium isotope ratio stability and survivorship in thermally altered bone and teeth is limited. This is surprising given the potential implications for geolocation inquiries of cremains. This research demonstrates the utility and potential of strontium isotope analysis (87Sr/86Sr) in the contexts of thermally altered osteoarchaeological materials with the focus to reconstruct the geographic origins of the prehistoric cremated human remains from the Late Woodland period (600–850 CE) Perrins Ledge crematory, located in the Lower Illinois River Valley of the American Midwest. This mortuary site is unique in both regional and temporal contexts as an isolated crematorium structure containing at least 13 individuals (ten adults and three non-adults) represented by burned human skeletal remains of unknown origins. Strontium isotope signatures derived from bone and enamel samples of the cremains are compared with values obtained from osteoarchaeological faunal remains from three contemporary neighboring sites (Carlin, Apple Creek, and Newbridge) using thermal ionization mass spectrometry. Results indicate that the majority of the Perrins Ledge individuals reflect signatures beyond the standard (two-sigma) range considered local, with one adult bone and enamel sample and two of the three non-adult enamel samples that mirror local signatures.