Sulphur isotope evidence for freshwater fish consumption: a case study from the Danube Gorges, SE Europe

To explore the use of sulphur isotopes as an indicator of the consumption of freshwater fish, we undertook sulphur isotope analysis on bone collagen extracted from humans and animals from five archaeological sites from the Danube Gorges region dating from the Mesolithic to the middle Neolithic periods. The results show a difference in the sulphur isotope values between freshwater and terrestrial ecosystems of 8.7‰. To reconstruct human diets, bone collagen from 24 individuals was analysed for carbon, nitrogen and sulphur isotopic values. The nitrogen isotope ratios ranged from 10.3 to 16.5‰ and the carbon isotope ratios ranged from −20.8 to −18.3‰. Low nitrogen isotope values were found for individuals with low sulphur isotope ratios reflecting the low sulphur isotopic values of the terrestrial animals. The highest human nitrogen isotope values coincided with higher sulphur isotope ratios, which are related to the higher sulphur isotope values of the freshwater fish. Intermediate human sulphur isotopic ratios between these two extremes showed mixed diets of both terrestrial and freshwater resources.