Strontium ( Sr/ Sr) isotope analysis of the Namu skeletal assemblage: A study of past human migration on Taumako, a Polynesian Outlier in the eastern Solomon Islands.

OBJECTIVES

This study aims to assess if inter-island mobility can be identified during the Namu period (ca. 1,510-1800 AD) using Sr/ Sr analysis of dental enamel for individuals from the Namu burial ground on Taumako Island in the eastern Solomon Island Chain. Historic evidence from this region suggests that females migrated between the Duff, Reef, and Santa Cruz islands for marriage purposes. We hypothesize that observable trends in migrational ( Sr/ Sr) and dietary (δ C and δ N) isotopes can reveal the relationship between demographic factors, social status, diet, and female mobility on Taumako.

METHODS

This research analyzes enamel Sr/ Sr for 58 individuals in the Namu skeletal sample. The Sr/ Sr results were compared with published dietary isotope data (bone collagen and dentin δ C and δ N values) and type/number of grave goods to assess whether trends within the data may be related to sex, age, or burial wealth.

RESULTS

The results show that females display significantly higher Sr/ Sr values compared to males. One young adult female displayed a Sr/ Sr value that was +2SD outside the mean for the sampled individuals. A linear mixed-effects model and principle components analysis of Sr/ Sr, δ C, and δ N values suggest that wealth, sex, and age-cohort membership have an observable influence on the isotopic variation for the Taumako population.

CONCLUSION

We suggest that during the Namu period, Taumako was patrilocal and that some females migrated there from the nearby Santa Cruz and Reef islands. One female immigrated to Taumako from a geologically distinct region outside of the Duff, Reef, and Santa Cruz Island groups.