Stable isotopic analysis of Early bronze Age human and animal diets in central France (Auvergne)

International audienceMetal exploitation, modifications of the production system and manifestation of a social hierarchy are attested in the Early Bronze Age in Western Europe. These social and technical modifications do not seem to appear in a linear way but rather according to regional strategies. Moreover, the subsistence pattern seems mainly turned toward herding and agriculture with a different access to the food items in relation with social and biological criteria. Based on an isotopic approach, the objectives of this research are (1) to characterize the dietary practices of individuals buried in Auvergne in the Centre of France and (2) to evaluate the impact of the local environment on the food consumed by humans and the management of their food resources. Stable isotopic analyses (δ13C, δ15N) were performed on bone collagens from 75 human individuals and 22 animal remains belonged to three contemporary nearby archaeological sites dated to the Early Bronze Age (ca. 2300-1600 BC cal.): Chantemerle (Puy de Dôme), Orcet/Le Tourteix (Puy de Dôme), and Dallet/Machal (Puy de Dôme). Results show a wide dispersion of both carbon and nitrogen isotopic values for animal (-21.7 to -19.5‰, m ± 1 Ϭ = -20.7±0.6‰; 4.3 to 10.5‰, 7.3±1.7‰; n=22) and for nitrogen isotopic values for human individuals (-20.6 to -19.6‰, -19.9±0.3‰ ; 7.9 to 13‰, 10.6±0.8‰; n=75). These values are in relation either with a varied environment or the consumption of diversified food items. Isotopic data do not show any significant consumption and/or practical of the cultivation of the millet for both animal and human groups whereas its cultivation is attested in France during the Bronze Age. For animals, δ15N values of ovicaprid are higher than expected indicating a probable consumption of specific fodder enriched in 15N. The high nitrogen isotopic range for humans (5‰) suggest a differential consumption of animal proteins within the group, which should come from the meat and secondary products (milk, butter) and a differential consumption of the meat of suid, bovid and ovicaprid. The human inter-variability of isotopic ratios has been analyzed according biological and funerary criteria, no significant cluster appears. The apparent social hierarchy of certain subjects buried in pit well-architectured is not expressed either by significant food behaviors