Exploring shifts in Roman subsistence practises through a Bayesian meta-analysis of isotopic data

In our presentation we explore the interplay between shifting human subsistence practises and the establishing, expansion, apogeum and collapse of the Roman Empire. To achieve this, we introduce “Isotópia”, a collection of 695 human, animal, and plant stable isotope data (δ13C, δ15N, δ18O, δ34S, 87Sr/86Sr) measured on archaeological material dated between 800 BCE and 500 CE and set within the geographical extension of the Roman Empire. The increasing number of isotopic datasets has led to a significant accumulation of data that can be gathered together within independent databases. Amassed isotopic data, combined with historical, archaeological and biological metadata, represent a palimpsest of information providing for new insights on past human lifeways at different scales and resolutions. Isotópia is part of the IsoMemo&Pandora initiatives bringing together a network of independent isotopic databases and aiming to investigate past human societies via open-access compiled data and advanced spatio-temporal Bayesian modelling tools. We combine Isotópia and the CIMA isotopic database on medieval Europe and employ Bayesian models to explore subsistence practises over nearly two millennia. Preliminary results of the meta-analysis suggest an increase in both δ13C and δ15N values during the Roman imperial period, which could be explained by a general increase in marine protein consumption, imports of 15N-enriched cereals from North Africa and more intensive manuring and animal husbandry. A following decrease of δ13C and δ15N values during the Late Antiquity (300-600 CE) possibly relates to political and economic collapse, depopulation processes and different cultural traditions derived from incoming populations but also to climatic and/or environmental changes. Our results illustrate the research potential of large-scale meta-analysis of bioarchaeological data and obtained preliminary results reveal clear links between historical developments and human lifeways in pre-Roman, Roman and Post-Roman Europe.