Early medieval Italian Alps: reconstructing diet and mobility in the valleys

In Early Middle Ages (sixth–eleventh centuries AD), South Tyrol (Italian Alps) played a key role for geographical and military reasons. Historical sources document that allochthonous groups (germani) entered the territory, and the material culture shows mutual cultural exchanges between autochthonous and germani. Besides the nature of the migration, the demographic and socio-cultural impacts on the local population are still unknown. Stable isotope analyses were performed to provide insights into dietary patterns, subsistence strategies, changes in socio-economic structures, and mobility, according to spatial (e.g. valleys, altitudes) and chronological (centuries) parameters. Bone collagen of 32 faunal and 91 human bone samples from nine sites, located at different altitudes, was extracted for stable carbon, nitrogen, and sulphur isotope analyses. In total, 94% (30/32) of the faunal remains were of good quality, while the humans displayed 93% (85/91) of good quality samples for δ13C and δ15N and 44% (40/91) for δ34S stable isotopes. The isotopic results of the animals reflected a terrestrial-based diet. Statistical differences were observed within and among the humans of the different valleys. The δ13C values of individuals sampled from higher altitudes indicated a mainly C3 plant-based diet compared to areas at lower altitudes, where more positive δ13C values showed an intake of C4 plants. The δ15N values suggested a terrestrial-based diet with a greater consumption of animal proteins at higher altitudes. The data revealed higher variability in δ34S values in the Adige valley, with individuals probably migrating and/or changing dietary habits.