Scientists at the Eberhard Karls University in Tübingen (Germany) found that Neanderthals had sophisticated techniques for making synthetic materials. The researchers came to this conclusion after studying birch tar, which is used as an adhesive to strengthen stone tools. This is reported in an article published in the journal Archaeological and Anthropological Sciences.

The researchers analyzed two items made from birch resin and found in the German archaeological site of Königsaue. They date back to between 45,000 and 80,000 years ago. It is assumed that birch glue could be made either due to a unique production technology, that is, to be a synthetic material, or it was originally found on stones in the forest after a fire, after which the Neanderthals simply reproduced the natural process in the form of a condensation method.

The researchers compared the chemical composition of the birch resin artifacts with samples obtained from various methods - two above ground and three underground. For analysis, infrared spectroscopy, gas chromatography and mass spectrometry, as well as computed tomography were used. With underground methods, the access of oxygen to the wood is difficult, which leaves a clear chemical imprint.

It turned out that to obtain glue, Neanderthals used a more efficient method of stepwise distillation with limited oxygen supply during underground heating of wood. Such a complex approach would hardly have been developed as a result of a casual observation of a natural process. It is assumed that this technique began with simpler methods, which gradually became more complicated through experimentation. This points to the advanced cognitive skills of Neanderthals, and is also the oldest known example of the creation of technology in human history.