ArcHives—combined palynological, genomic and lipid analysis of medieval wax seals

Beeswax is a product of honeybees ( Apis mellifera ) and has been used extensively through time, especially as the primary component in medieval sealing wax for authenticating millions of documents. Today, these seals form large collections which, along with the historical information in the documents that the seals are attached to, could be a potential biomolecular archive for honeybees. Here, we investigate the possibility of obtaining biological information from medieval wax seals by performing a palynological and shotgun metagenomic analysis on eight medieval wax seal fragments. Our palynological results show that some pollen and fungal spores remain in the seals, albeit very little. Only one out of eight samples yielded enough DNA for sequencing. Moreover, only minor parts of the DNA reads could be taxonomically identified and were identified as plant and fungal DNA. These results demonstrate some potential for using wax seals as biological archives, but most importantly provides a framework for future studies, in addition to understanding further the degradation of seals as cultural heritage objects. We emphasize that future analyses should focus on other methodologies to retrieve data for historical context or alternatively improve molecular methods and screen sample collections broadly.