Mesolithic dietary heterogeneity on the European Atlantic Coastline: Stable isotope insights into hunter-gatherer diet and subsistence in the Sado Valley, Portugal

Stable carbon and nitrogen isotope data from the bone collagen of human remains excavated in the Sado Valley in the Alentejo region of Portugal provide evidence for the existence of two Mesolithic communities living in close proximity along the shores of an estuarine environment with significantly different diets. These findings add to the limited isotope paleodiet data set from this period in southern Europe and offer a valuable contribution to understandings of the wider European Mesolithic along the Atlantic coastline by (1) providing evidence of coastal Mesolithic hunter-gatherers with mainly terrestrial diets in Europe and (2) suggesting the presence of regional heterogeneity, at a small geographical scale, in subsistence choices among coastal Mesolithic groups. These results show the complexity of human subsistence adaptations in the European Mesolithic and have wider-reaching implications for understanding hunter-gatherer group interactions.