Birch bark tar, the oldest glue in the world, was in use for at least 50,000 years, from the Palaeolithic Period up until the time of the Gauls. Made by heating birch bark, it served as an adhesive for hafting tools and decorating objects.
     Scientists mistakenly thought it had been abandoned in western Europe at the end of the Iron Age (800-25 BCE) and replaced by conifer resins, around which a full-fledged industry developed during the Roman period. But by studying artefacts that date back to the first six centuries CE through the lens of chemistry, archaeology, and textual analysis, researchers from the CNRS, Université Nice Sophia Antipolis / Université Côte d'Azur, and Inrap have discovered birch tar was being used right up to late antiquity, if not longer.
     
Edited from EurekAlert!, PhysORG (13 November 2019)