Figure 3. BLG pattern in dental calculus is consistent with bone collagen stable isotope evidence of a decline of the dairy economy in Norse Greenland with the onset of the Little Ice Age (ca.1250 CE).

(a) Total spectra matching BLG peptides recovered from dental calculus samples from the earlier Tjodhildes Church at Ø29a Brattahlið in the Eastern Settlement (individuals KAL1064 and KAL1052) and from the later V51 Sandnes site in the Western Settlement (individuals KAL934, KAL933, KAL936, and KAL930). (b) Bone collagen carbon and nitrogen stable isotope values measured from burials at Tjodhildes Church (black) and Sandnes (white)²²,²³, showing a major dietary shift toward marine resources at the later Sandnes site. Isotopic values for individuals also analyzed for dental calculus BLG peptides are represented by triangles, and from left to right on the x-axis are: KAL1064, KAL1052, KAL934, KAL933, KAL936, and KAL930. Isotopic data for KAL1064 and KAL1052 were measured in this study.