Andrew Michael Zipkin

ANDREW ZIPKIN, Arizona State University, Tempe, Arizona, was awarded a grant in April 2019 to aid research on “Isotopic Provenience of Ostrich Eggshell Beads to Uncover Social Networks of the Past.” Ancient and recent hunter-gatherers and pastoralists used ostrich eggshell (OES) beads to make valued personal ornaments that were gifted to underwrite relations of mutual support that increased resilience to environmental, demographic, and social pressures. The distance between the geographic origin and deposition points and the diversity in origin for beads in an object (e.g. a necklace) can be used as proxies for the scale of social networks. This research was the first phase of a multi-year project focused on provenience analysis of OES beads in the Kalahari Desert of Namibia. Using 111 modern plant samples collected in the Kalahari study area in 2019, the project constructed a spatially explicit predictive model of strontium isotope ratio (87Sr/86Sr) variation on the landscape. 87Sr/86Sr results showed significant differences when categorized by their associated bedrock formation, indicating that strontium available for uptake through ostrich diet and incorporation into OES is predominantly locally derived from bedrock weathering. In addition, minimally destructive laser ablation mass spectrometry was demonstrated to be an effective method for collecting 87Sr/86Sr data using modern ethnographic OES ornaments. These findings demonstrate that strontium isotope-based provenience analysis of OES in this study area is a viable approach.