Changing subsistence practices in pre-European populations of South Vanuatu

Differences in dietary patterns between the islands of South Vanuatu are expected due to differences in ecological and cultural characteristics of the islands and their complex histories of settlement, adaptation and interaction. This paper examines the human dietary practices of 32 individuals from three of the five islands in the region: Aniwa, Futuna and Tanna, between 2000 BP and the 20th century, using for the first time carbon and nitrogen isotope data measured in bone collagen. Our analysis includes an expanded baseline of local faunal and plant resources, with taxonomic identification of local faunal remains enhanced by proteomic determinations (Zooarchaeology by Mass Spectrometry; ZooMS). Human collagen δ¹³C values ranged from −19.7 to −16.2 ‰, and δ¹⁵N values from 6,3 to 9,7 ‰, with a large inter-individual variability. Based on our improved baseline, we suggested that the individuals with the highest δ¹³C and δ¹⁵N values would have consumed marine coral reef fish along with C3 plants. An individual with the lowest δ¹³C and δ¹⁵N values could have consumed mainly resources from mangrove. Four patterns were identified that may reflect the geographical characteristics of the islands, the normalisation of diet over time, the nutritional stress of individuals in relation to environmental and climatic factors, and social differentiation in food acquisition and/or consumption, illustrating issues of equifinality in bioarchaeological data interpretation.