Exploring the Neolithic food system through the lipid residue analysis of heat-altered stones

Heat-altered stones (HAS) remain a largely untapped archaeological resource, despite their long-standing association with cooking and food processing. While Early Neolithic culinary practices are frequently reconstructed through archaeozoological, botanical, and ceramic analyses, HAS have yet to be fully integrated into the standard analytical toolkit. This research addresses this gap by investigating the potential of HAS as molecular archives of past human activities, including subsistence practices. With this aim, we employed a multi-analytical approach, based on observation of heat-induced modifications and molecular and isotopic composition of lipids of HAS of two Early Neolithic sites (La Draga, lacustrin context, Spain and Pendimoun, rockshelter, France). We showed that HAS are characterised by a mixture of environmental and anthropogenic-derived lipids at both sites, with a higher yield of lipids in Pendimoun. At Pendimoun, our results revealed that HAS from the Fireplace and the Cooking Area retained distinct lipid sources. In the Fireplace, the lipid signal in the HAS is mainly inherited from the surrounding sediment. In contrast, samples from the Cooking Area reveal molecular signatures associated with the processing of adipose fats and dairy products. These results align with the contents of ceramic vessels previously investigated at the site. Our study highlights the significant potential of HAS to inform past culinary practices and calls for their inclusion in broader research on prehistoric economies, technology, and diet.