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 BC) and replaced by conifer resins, around which a full-fledged industry developed during the Roman period.
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Source: Phys.org