Childhood mobility revealed by strontium isotope analysis: a review of the multiple tooth sampling approach

Strontium isotope analysis of archeological skeletal materials is a highly effective and commonly employed analytical tool to investigate past human mobility and migration. Most such studies to date have focused on the analysis of a single tooth sample per individual to identify migration. Increasingly, however, studies have analyzed multiple teeth from the same individual permitting the detection of migrations occurring during childhood, more fine-grained temporal resolution of the age at which migration(s) occurred, and even the identification of multiple migration episodes. In this study, we review the application of such approaches to a wide range of archeological contexts worldwide. We compiled and analyzed published 87Sr/86Sr data for 1043 individuals from 122 sites to explore the potential variability of childhood mobility patterns cross-culturally. The results demonstrate a high degree of variability in childhood mobility that differs significantly between different regions and time periods. Potential interpretations involved in multiple tooth 87Sr/86Sr analysis are reviewed, including heterogeneity in variance of regional 87Sr/86Sr, as well as variability in human mobility patterns such as residential change of whole family, fosterage, herding activities, post-marital residence rules, or forced migrations. Various limitations and caveats concerning the multiple teeth sampling approach are also critically discussed.