Researchers have discovered traces of ancient "glue" on a stone tool from 50,000 which indicates complex thinking by Neanderthals.
The glue found on the tool was made from birch tar in a process requiring forward planning and involving several different steps, which showed that Neanderthals are capable of complex thinking.
The discovery adds to the increasing evidence that the capabilities of the Neanderthals have been previously underestimated.
While only a handful of Neanderthal tools showed signs of adhesive, the researchers believe that the process could have been used widely. The tool was discovered in the Netherlands after spending the last 50,000 years under the North Sea, which may have helped in the preservation of the tar adhesive.
According to co-author Marcel Niekus from the Stichting STONE/Foundation for Stone Age Research in Groningen, the simple stone flake may have been used either for cutting plant fibres or for scraping animal skins.
Niekus also mentioned that while birch tar may have been used by Neanderthals to attach stone tools to wooden handles, this particular tool probably had a tar-only grip since there was no imprint from a wood or bone shaft in the tar. This design would have enabled the user to to apply more pressure to the stone flake without cutting their hands, making it a precision cutting tool.
Dr. Niekus pointed out: "They had to really plan ahead, because the process needs at least 40 kilograms of wood. In steppe tundra conditions that's not easy to collect, because you only have dwarf birch trees. They also had to invest time and energy in building the fire and extracting the tar."
He added: "With the investment in time needed, you would expect them only to do it with special hunting weapons, but they did it with special domestic tools as well. We think the use of birch tar was quite widespread."
