The process of making Neanderthal tools could have been simpler than we thought

Neanderthals and other humans produced a tarry glue from birch bark; this has long been regarded as evidence of a high level of cognitive and cultural development. Researchers had long believed that birch tar – used by Neanderthals to make tools – could only be created by a complex process in which the bark had to be heated in the absence of beans. air.

However, an international team led by researchers from the University of Tübingen and including professors from the Department of Anthropology at the University of New York and the TUYON School of Engineering at the University New York discovered that there was a very simple way to make this glue useful.

The study was published on August 19 in Proceedings of the National Academy of Sciences (PNAS)

"Our article challenges common beliefs that the presence of birch tar in the archaeological assemblages of Neanderthal means that they possessed sophisticated cognitive abilities," said co-author Radu Iovita, Paleoanthropologist and Paleolithic archaeologist from Department of Anthropology, University of New York, USA. the Department of Prehistory and Quaternary Ecology of the University of Tübingen.

Previous researchers had experimented with pits, clay structures, ash mounds, and metal and ceramic vases as a means of heating the bark in the absence of oxygen. Instead, this research team experimented with ordinary materials available in the Stone Age. They picked up some birch bark or dead bark cut in the forest and burned it near flat stones. After three hours, the process gave a usable amount of a black sticky material. Tar could easily be removed from the surface of stones. Its molecular characteristics were similar to the archaeological samples of Neanderthal sites and, more importantly, it formed a stronger glue than the tar produced in more complex processes without oxygen.

The team used its adhesive to make a wood scraping tool and turned to a robot using a force control technology developed by Ludovic Righetti and Johannes Pfleging.

Righetti is an associate professor in the electrical and computer engineering and mechanical and aerospace engineering departments at NYU Tandon and a senior scientist at the Max Planck Institute for Intelligent Systems in Tübingen. Pfleging is a Visiting Scholar in Anthropology at NYU and a PhD Candidate in Robotics at the Swiss Federal Institute of Technology (ETH) in Zurich, Switzerland.

Their robot arm has dragged the tool with a precision that humans can not emulate more than 170 shots. The approach also allowed researchers to accurately measure effects: the tool showed no weakening of the adhesive bond.

In another test, the researchers used the adhesive to stick a scraper to a wooden handle, as had the Neanderthals. Iovita was able to scrape the hard outer membrane of the femur of a calf.

The researchers explain that this method of making birch tar is so simple that early humans would have easily discovered it by chance during their daily activities. The production and use of birch tar can no longer serve as an indicator of modern or complex behavior.

"The extraction of birch tar does not prove the behavioral complexity of Neanderthal", appears in PNAS – Proceedings of the National Academy of Sciences, week of August 19, 2019.