Strontium isotopes and concentrations in cremated bones suggest an increased salt consumption in Gallo-Roman diet

The high temperatures reached during cremation lead to the destruction of organic matter preventing the use of traditional isotopic methods for dietary reconstructions. Still, strontium isotope (⁸⁷Sr/⁸⁶Sr) and concentration ([Sr]) analyses of cremated human remains offer a novel way to assess changing consumption patterns in past populations that practiced cremation, as evidenced by a large amount of new data obtained from Metal Ages and Gallo-Roman human remains from Destelbergen, Belgium. The Gallo-Roman results show significantly higher [Sr] and a narrower interquartile range in ⁸⁷Sr/⁸⁶Sr (0.7093-0.7095), close to the value of modern-day seawater (0.7092). This contrasts with the Metal Ages results, which display lower concentrations and a wider range in ⁸⁷Sr/⁸⁶Sr (0.7094-0.7098). This typical Sr signature is also reflected in other sites and is most likely related to an introduction of marine Sr in the form of salt as a food preservative (e.g. salt-rich preserved meat, fish and fish sauce). Paradoxically, this study highlights caution is needed when using ⁸⁷Sr/⁸⁶Sr for palaeomobility studies in populations with high salt consumption.