Neanderthals made the very first adhesive without a lot of fuss

31 August 2017

The world’s oldest known adhesive was made by Neanderthals. But how on earth did they make that sticky stuff 200,000 years ago? Archaeologists from Leiden University have discovered three possibilities. Nature Scientific Reports published an article about these today. The research was made possible by funding from the NWO Talent Scheme and ARCHON Research School of Archaeology.

Tar yield from pit roll method in bark container. Credit P. KozowykTar yield from pit roll method in bark container. Credit P. Kozowyk

A Neanderthal spear is made out of two parts: a wooden shaft and a flint spearhead. The adhesive holding the shaft and spearhead together had remained a mystery to archaeologists. The Neanderthals used tar from birch bark, a substance archaeologists often thought was difficult to extract.

Archaeologists from Leiden University have now shown that this assumption is incorrect. The scientists working under Paul Kozowyk and Geeske Langejans discovered no less than three different ways of extracting tar from the birch bark. For the simplest method nothing more than a roll of bark and an open fire were needed. Thanks to that method Neanderthals could already produce adhesive 200,000 years ago.

The scientists made this amazing discovery when they began experimenting with the few instruments the Neanderthals had available. The researchers used experimental archaeology because only a very small amount of adhesive has remained conserved and no direct archaeological proof was found from which it was possible to deduce the production methods used by the Neanderthals.

Temperature control

“Earlier attempts by scientists only succeeded in extracting a small amount of tar from birch bark, or even nothing at all,” says Kozowyk. “It was thought that it was absolutely necessary to keep the temperature of the fire constant. But we discovered that there are various ways of producing tar and that some of these can also work with large variations in temperature. So meticulously controlling the temperature of the fire is not as important as originally thought.”
Kozowyk and his colleagues suspected that the Neanderthals discovered tar production by combining existing knowledge and materials. The process most likely began with a simple method using only fire and birch bark. Later on, the Neanderthals switched to a more complex method that yielded greater amounts of tar.

More information

Kozowyk, P., Soressi, M., Pomstra, D., Langejans, G. (2017). Experimental methods for the Palaeolithic dry distillation of birch bark: implications for the origin and development of Neanderthal adhesive technology. Scientific Reports, http://nature.com/articles/doi:10.1038/s41598-017-08106-7

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