A02_01

Compound-specific radiocarbon dating of lipid residues in pottery vessels: a new approach for detecting the exploitation of marine resources

Casanova E ^1,2, Knowles T², Bayliss A³, Barclay A⁴, Walton-Doyle C², Evershed R

¹Museum national d'histoire naturelle, Paris, France, ²University of Bristol, Bristol, UK, ³Historic England, London, UK, ⁴Costwold Archaeology, Cirencester, UK

Over the last decades, organic residue analysis has been shown to be especially useful in ancient diet reconstruction; however, it is only recently that the direct radiocarbon dating of lipid residues has become a reliable method for dating pottery vessels and food procurement activities. We applied lipid residue analysis to late Bronze Age pottery vessels from the site of Cliffs End Farm (UK), previously dated by their visible charred residues and dated four of these vessels by compound-specific radiocarbon analysis (CSRA) of their absorbed lipids. Lipid biomarker detection was limited to only one class of aquatic biomarker in four vessels, which indicated that the diet relied mainly on terrestrial animals. Four vessels datable from their absorbed lipids produced ¹⁴C measurements significantly older than those on the charred residues, suggesting a reservoir effect affecting the dated lipids. Furthermore, the low abundance of pig remains (1-4%) at the site suggests that enriched δ¹³C16:0 and δ¹³C18:0 values recorded on the absorbed fatty acids were caused by marine contributions. The percentage of marine products in the CSRA dated vessels was quantified using the δ¹³C values of individual fatty acids and from a modern reference database. These percentages were incorporated in mixed-source radiocarbon calibration using OxCal for the correction of a marine reservoir effect. Therefore, the combination of lipid compositions, radiocarbon dates and faunal analyses enabled the identification of marine product exploitation at the site. Finally, this allowed comparisons to be made with the dates of charred residues obtained from the same sherds.