Pig diet in medieval York: carbon and nitrogen stable isotopes

This study investigates bone stable isotopes from pigs from medieval York, to characterise the pigs' diet and to explore their contribution to isotopic values from contemporary human bones. Pig bones from the Swinegate (N=9) and Coppergate (N=14) sites were used for carbon and nitrogen stable isotope analysis to test the hypothesis that the majority of pigs in medieval York were yard-kept and fed on scraps and fish waste, elevating their nitrogen ratios. The results show that the Swinegate and Coppergate pigs gave nitrogen isotope values similar to contemporary sheep and therefore that animal protein made little or no dietary contribution. One sample showed C and N results consistent with more animal protein in the diet, and we propose that this could have been a yard-kept pig consuming human refuse. The majority of the data indicate that the pigs were eating a largely herbivorous diet and that pigs in medieval York may have been raised in rural or woodland locations rather than in the city.