Archeologists have been finding lumps of adhesive tar on Neanderthal sites in both Italy and Germany over the past few decades. After testing the tar, they found that it was made from birch bark. The Neanderthals mostly used the adhesive tar for weapon production around 200,000 years ago and made it without using ceramic pots to help produce larger quantities of the tar.
The researchers also predict that as many as 3 techniques were used for the production of the tar and carried out these techniques to produce tar with resources only available around 200,000 years ago. One of the methods were to place embers and ash over birch bark and tie the bark with fresh wood fiber. Another method was to place hot embers directly on top of a roll of birch bark places over a pit. This produced the tar. A final method was to put a birch bark container in a pit with a loose roll of the bark placed on organic mesh over the pit. The bark was then covered with first and a fire was lit over the entire mount. This last method produced more tar, but required more tools.