Bone collagen is the protein scaffold that gives bone its flexibility - chemically the same stuff used to make sweets like gummi bears. Gummi bears are made from gelatin, which is collagen extracted by boiling the bones, skin, and connective tissue of animals.

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We sample rib bones to study diet, because ribs regenerate over six to seven years. The collagen in ribs thus reflects food consumed over roughly the last decade of a person's life. Stable isotope analysis of bulk collagen extracted from rib samples can therefore reconstruct what an individual was eating with considerable precision: carbon and nitrogen isotope ratios in this collagen reflect the food web an individual was part of, with high nitrogen values indicating a diet rich in animal protein and elevated marine carbon signalling significant consumption of fish. 

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Analysis of SL15 returned values consistent with a high-status diet, rich in fish and terrestrial protein - just the kind of diet associated with wealthy households in the late medieval North East of England, where access to marine resources was a marker of social standing rather than simple proximity to the sea.

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In the final years of his life, SL15 had no teeth, and the flattening of his mandible indicates that he was using the gum ridge itself as a chewing surface. Consuming a protein-rich diet under those conditions would have required either considerable effort, more likely, assistance: food prepared in forms that required little or no chewing, or help from others with eating. The isotopic record thus does more than confirm his social standing. It places him within a community that was actively sustaining him, preparing food in ways that accommodated his needs, and ensuring that he continued to eat well even when eating had become difficult.