At the world's edge: Reconstructing diet and geographic origins in medieval Iceland using isotope and trace element analyses.

OBJECTIVES: A multi-isotope study was conducted on individuals buried at Skriðuklaustur monastery (AD 1493-1554) to investigate their geographic origins and dietary composition. Comparative material from individuals excavated from Skeljastaðir, an inland farm site was also analyzed. MATERIALS AND METHODS: Bone collagen was extracted from 50 humans (Skriðuklaustur and Skeljastaðir) and 25 animals (Skriðuklaustur) and analyzed for δ13 C, δ15 N, and δ34 S. Dental enamel samples from 31 individuals (Skriðuklaustur) were also analyzed for 87 Sr/86 Sr, δ18 O, δ13 C, and trace elements (Pb, Sr, Zn, Ba). RESULTS: The mean value determined from individuals from Skriðuklaustur (n = 36) was δ13 C = -18.7 ± 0.8‰, δ15 N = 12.8 ± 1.1‰, and δ34 S = 9.0 ± 1.6‰, whereas at Skeljastaðir (n = 14), it was δ13 C = -20.5 ± 0.8‰, δ15 N = 7.8 ± 0.9‰, and δ34 S = 9.4 ± 1.6‰. At Skriðuklaustur, human dental enamel samples (n = 31) provided a 87 Sr/86 Sr range of 0.7060-0.7088, δ18 Ophosphate from 13.9 to 16.1‰ and δ13 Ccarbonate from -16.6 to -12.9‰. Inferred drinking water (δ18 Odw ) values range from -12.3 to -8.9‰. Sr concentrations range from 25.8 to 156.7 ppm, Ba from 0.11 to 0.81 ppm, Zn from 43.8 to 145.8 ppm, and Pb from 0.13 to 9.40 ppm. DISCUSSION: A combination of results indicates that the people from Skriðuklaustur were born in Iceland, but some lived inland during childhood while others lived closer to the coast. Since Skriðuklaustur was a hospital, these individuals may have sought medical treatment at the monastery. The δ13 C and δ15 N values determined from bone collagen indicate that the people residing at Skriðuklaustur consumed a diet high in marine protein, while those residing at Skeljastaðir exhibit values more consistent with terrestrial resources.

Ancient genomes from Iceland reveal the making of a human population.

Opportunities to directly study the founding of a human population and its subsequent evolutionary history are rare. Using genome sequence data from 27 ancient Icelanders, we demonstrate that they are a combination of Norse, Gaelic, and admixed individuals. We further show that these ancient Icelanders are markedly more similar to their source populations in Scandinavia and the British-Irish Isles than to contemporary Icelanders, who have been shaped by 1100 years of extensive genetic drift. Finally, we report evidence of unequal contributions from the ancient founders to the contemporary Icelandic gene pool. These results provide detailed insights into the making of a human population that has proven extraordinarily useful for the discovery of genotype-phenotype associations.