Fingernails and diet: Stable isotope signatures of a marine hunting community from modern Uummannaq, North Greenland

C, N ad S stable isotope compositions of fossil human bones are frequently used in palaeodiet studies, but results from strictly marine communities are scarce. Modern hunting and fishing Inuit Greenlanders in the Uummannaq District in North Greenland are known to live from a diet high in local marine food (seal, whale, halibut) combined with basic foods (bread, cereals, dairy products) imported from Denmark and thus provide an excellent test population. Here were report diet anamnesis data and stable isotope compositions of fingernails from 82 Uummannaq District Inuit individuals and a control group of 32 Danes living in Denmark. The Uummannaq fingernails are significantly enriched in 13C, 15N, 34S compared to the Danish group (t-test, 99% conf. level). Calculated from isotope modelling, the Uummannaq Inuit get on average 50% of their diet (range 28 to 68%) from marine food placed high in the trophic system reflecting high proportions of carnivorous marine mammals (seal) in the diet, and the most 15N enriched individuals have trophic positions close to polar bears. Comparisons to other human hair and fingernail studies reveal the Uummannaq Inuit to be the most heavy-isotope enriched modern community analysed so far. The consistency of our data lead us to conclude that the fingernail isotope signatures are reliable measures of modern human diet composition and that fingernail isotope analyses can provide an easy quantitative supplement to other diet studies. Sulphur isotope analyses in special may provide unambiguous results in terrestrial-to-marine mixing systems.