Isotopic evidence for anthropogenic lead exposure on a 17th/18th century Barbadian plantation

Historical overview and new directions in bioarchaeological trace element analysis: a review

Given their strong affinity for the skeleton, trace elements are often stored in bones and teeth long term. Diet, geography, health, disease, social status, activity, and occupation are some factors which may cause differential exposure to, and uptake of, trace elements, theoretically introducing variability in their concentrations and/or ratios in the skeleton. Trace element analysis of bioarchaeological remains has the potential, therefore, to provide rich insights into past human lifeways. This review provides a historical overview of bioarchaeological trace element analysis and comments on the current state of the discipline by highlighting approaches with growing momentum. Popularity for the discipline surged following preliminary studies in the 1960s to 1970s that demonstrated the utility of strontium (Sr) as a dietary indicator. During the 1980s, Sr/Ca ratio and multi-element studies were commonplace in bioarchaeology, linking trace elements with dietary phenomena. Interest in using trace elements for bioarchaeological inferences waned following a period of critiques in the late 1980s to 1990s that argued the discipline failed to account for diagenesis, simplified complex element uptake and regulation processes, and used several unsuitable elements for palaeodietary reconstruction (e.g. those under homeostatic regulation, those without a strong affinity for the skeleton). In the twenty-first century, trace element analyses have been primarily restricted to Sr and lead (Pb) isotope analysis and the study of toxic trace elements, though small pockets of bioarchaeology have continued to analyse multiple elements. Techniques such as micro-sampling, element mapping, and non-traditional stable isotope analysis have provided novel insights which hold the promise of helping to overcome limitations faced by the discipline.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s12520-020-01262-4.

Isotopic evidence for anthropogenic lead exposure on a 17th/18th century Barbadian plantation

OBJECTIVES

To identify and characterize anthropogenic lead sources on a 17th/18th century Barbadian plantation and to test if lead isotope analyses can be used to identify the geographic origins of first-generation African captives.

MATERIALS AND METHODS

We carried out lead (Pb) isotope analyses on dental enamel samples from 24 individuals from the Newton Plantation Cemetery in Barbados, which had previously been analyzed for strontium (Sr) and oxygen (O) isotope composition (Schroeder et al., American Journal of Physical Anthropology, 2009, 139:547-557) and Pb concentrations (Schroeder et al., American Journal of Physical Anthropology, 2013, 150:203-209.

RESULTS

We are able to identify British Pb sources, and more specifically Bristol/Mendips Pb, as the most likely source of anthropogenic Pb on the plantation, highlighting the impact of the British Atlantic economy on the lives of enslaved peoples in Barbados during the period of plantation slavery. Furthermore, we find that there is only one clear outlier among seven individuals who had previously been identified as African-born based on their enamel Sr isotope composition (Schroeder et al., American Journal of Physical Anthropology, 2009, 139:547-557). All other individuals present a very homogenous Pb isotope composition, which overlaps with that of British Pb sources.

CONCLUSION

Our results indicate that while Pb isotope analyses can help identify and further characterize the sources of anthropogenic Pb in plantation settings, they might not be suited for identifying the origins of African-born individuals in diasporic contexts.