Multi-isotope approaches to the Neolithic cemetery-cave of Bom Santo (Lisbon): new data and comparisons with fourth millennium BC populations from central–southern Portugal

Abstract

Previous multi-isotopic research on the human remains of the Neolithic cave-cemetery of Bom Santo (Lisbon, Portuguese Estremadura) led to the conclusion that this fourth millennium BC population was very heterogeneous at several levels. Two in particular were subsistence habits and mobility: although consumption of terrestrial foods was the norm, aquatic food sources totalling > 20% of overall diets were detected in 60% of the population, and, surprisingly, 79% of the individuals were classed as non-local, having lived most of their life in geologically older regions. These figures were however obtained on a sample of 15 individuals. Further isotopic analyses have enlarged the original sample to 35 individuals (i.e., half of the exhumed population) and were also employed in the study of the coeval cave-cemeteries of Barrao and Mureta. This has permitted a sounder depiction of past behaviours, with a structural difference being observed at both levels between Bom Santo and the latter sites: at the former cave, 70% of the population consumed > 20% of aquatic foods and 34% were non-local (23% from outside Estremadura), whereas the latter were all local and showed no signals of aquatic diets. Comparison with other fourth millennium BC populations in central-southern Portugal suggests a model where the exploitation of locally available aquatic/marine food sources was not mandatory but optional and that human mobility represented an important socio-economic behavioural feature of these (presumably) segmentary societies. How both aspects related to the then-emerging megalithic phenomenon is a question that should be investigated in future research.