Dietary inequality marker reveals 10,000 years of gender and cultural disparity in Europe.

Diet is a key to evaluating social and health inequalities over time, as it reflects disparities in access to resources often linked to socioeconomic and gender factors. Stable carbon and nitrogen isotopes, while semi-quantitative, typically limit intersite comparisons, as the results are tied to local baseline isotope values. In this study, we overcome this limitation by applying the interdecile ratio-a metric from economics-to isotope data from 12,281 individuals across 393 European sites over millennia. Our isotope-based dietary inequality index reveals the nonlinear evolution of dietary disparities over time and across different geographical areas. Sex-based disparities are evident throughout all time periods. Male individuals are consistently overrepresented in the upper deciles, indicating greater access to animal proteins, while females dominate the lower deciles, reflecting more restricted access. Neolithic societies exhibit homogeneous diets at the population level, but animal protein consumption tends to differ between men and women. As expected, Bronze Age carbon interdecile indexes mark increasing dietary inequality, likely linked to agricultural advances and social hierarchies. Dietary disparities peak during Antiquity, although the gap between the sexes narrows slightly. This diachronic analysis highlights the complex interactions between diet, social structures, and gender and provides a robust framework for comparative studies of health inequalities in archaeology.