Fast or feast: reconstructing diet in later medieval England by stable isotope analysis

A re-evaluation of the Longin collagen-extraction method shows that a lower reflux temperature reduces degradation of protein (“collagen”) remnants. This allows additional purification through ultrafiltration to isolate the >30kDalton fraction of the reflux product.

The delta 15N values of bone collagen from Eskimos and from Northwest Coast Indians dependent on salmon fishing are about 10 per mil more positive than those from agriculturalists in historic times. Among prehistoric humans, two groups dependent on marine food sources show bone collagen delta 15N values that are 4 to 6 per mil more positive than those from two agricultural groups. The nitrogen isotope ratios of bone collagen from prehistoric inhabitants of the Bahamas are anomalously low for reasons that relate to the biogeochemical cycle of nitrogen in coral reefs.