Investigating the presence of foreigners and pig husbandry in ancient Bali: Stable isotopes in human and domestic animal tooth enamel

Archaeological excavations at the Sembiran and Pacung archaeological sites in coastal Bali, Indonesia, have yielded pottery shards and other material culture that derives from India and other locations on the Asian mainland, demonstrating that about 2000 years ago the north coast of Bali was in contact with cultures from mainland Asia. The area may in fact have hosted a harbour and perhaps even a community of foreign traders or immigrants. The Sembiran and Pacung excavations also yielded human remains from the same time period. We performed strontium, oxygen and carbon stable isotope analyses of tooth enamel from nine human skeletons to investigate whether the people interred at Sembiran and Pacung were from the local area or had travelled there from a distant home. Strontium isotope ratios were also measured in seven archaeological pig (Sus cf. scrofa) teeth, one archaeological canid tooth, and five modern snail (Achatina fulica) shells to help identify the local strontium isotope signature. The people interred at Pacung and Sembiran had similar oxygen and carbon isotope ratios but varying strontium isotope ratios which were higher than expected based on geology. Despite the abundance of foreign materials recovered, our isotope data can be most parsimoniously explained as deriving from a group of locally raised individuals who had a varying mix of coastal and inland plant resources in their diets. In addition, strontium isotope ratios from the pig teeth show interesting clustering, suggesting that two or three different husbandry practices may have been employed.