Stable isotope palaeodiet study of humans and fauna from the multi-period (Iron Age, Viking and Late Medieval) site of Newark Bay, Orkney.

We report here on stable carbon and nitrogen isotope measurements of human and faunal bone collagen from the Iron Age, Viking Age, and Late Medieval site of Newark Bay, Orkney, Scotland. We found a wide range of results for humans in both δ13C (−15.4‰ to −20.3‰) and δ15N (8.6‰–15.6‰) values. The enriched carbon and nitrogen values indicate the consumption of significant amounts of marine protein, which is very unusual for post-Mesolithic (e.g. 4000 cal BC) UK and European populations. Also of interest is a statistically significant difference in δ13C (t = −2.48, p = 0.011) and δ15N (t = −2.44, p = 0.011) values, and therefore diets, between adult males and females at this site, with males (δ13C = −17.8 ± 1.2‰, δ15N = 13.2 ± 1.6‰) having, on average, a higher proportion of marine protein than females (δ13C = −18.9 ± 1.1‰, δ15N = 11.8 ± 1.8‰). The weaning age of the sub-adults was difficult to interpret due to the large isotopic variation in the adult females, but nearly all individuals between birth and 1.25 years have elevated δ15N values indicating that they were breastfed to some extent