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 O_phosphate from 13.9 to 16.1‰ and δ¹³ C_carbonate from -16.6 to -12.9‰. Inferred drinking water (δ¹⁸ O_dw ) 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.