Ancient DNA and biomarkers from artefacts: insights into technology and cultural practices in Neolithic Europe.

Birch bark tar was widely used throughout prehistoric Europe for hafting stone tools as well as various other purposes. While previous research has mainly focused on the identification and production of birch bark tar, its diverse uses remain to be fully explored. In this study, we combined ancient DNA with organic residue analysis to analyse 30 birch tar artefacts from nine Neolithic sites in and around the Alps. We identified birch tar as the main component, with some samples also containing conifer resin or tar, possibly added to modify its properties. Degradation markers indicate that tar used for ceramic repair was heated repeatedly, probably during cooking. Additionally, the presence of human and oral microbial DNA in some of the samples suggests the tar was chewed, in some cases by multiple individuals. The human DNA also enables us to determine the sex of those who chewed the tar, offering insights into gendered practices in the past, while plant and animal DNA shed light on past diets and the possible use of additives. This study underscores the value of integrating organic residue and ancient DNA analysis of archaeological artefacts to deepen our understanding of past cultural practices.