Neanderthals’ use of complex adhesives reveals higher cognitive abilities, scientists find

Neanderthals created stone tools held together by a multi-component adhesive, a team of scientists has discovered. His findings, which constitute the first evidence of a complex adhesive in Europe, suggest that these predecessors of modern humans had a higher level of cognition and cultural development than previously thought.

The work, reported in the journal Scientists progressincluded researchers from New York University, the University of Tübingen and the National Museums in Berlin.

“These surprisingly well-preserved tools present a technical solution broadly similar to examples of tools made by early modern humans in Africa, but the exact recipe reflects a Neanderthal ‘version,’ which is the production of handles for hand-held tools,” says Radu Iovita. , associate professor at the Center for the Study of Human Origins at New York University.

The research team, led by Patrick Schmidt from the Ancient Prehistory and Quaternary Ecology section of the University of Tübingen and Ewa Dutkiewicz from the Museum of Prehistory and Ancient History at the National Museums in Berlin, re-examined previous discoveries from Le Moustier, an archaeological site in France discovered at the beginning of the 20th century.

The Moustier stone tools, used by Neanderthals in the Mousterian Middle Paleolithic between 120,000 and 40,000 years ago, are preserved in the collection of the Museum of Prehistory and Ancient History in Berlin and had not been examined in detail previously. The tools were rediscovered during an internal review of the collection and their scientific value was recognized.

“The items had been individually wrapped and untouched since the 1960s,” Dutkiewicz says. “As a result, the adhering remains of organic substances were very well preserved.”

Researchers found traces of a mixture of ocher and bitumen on several stone tools, such as scrapers, flakes and blades. Ocher is a natural earth pigment; Bitumen is a component of asphalt and can be produced from crude oil, but it also occurs naturally in the ground.

“We were surprised that the oche content was above 50%,” says Schmidt. “Indeed, air-dried bitumen can be used as is as an adhesive, but loses its adhesive properties when such large proportions of ocher are added.”

He and his team examined these materials in tensile tests (used to determine strength) and other measurements.

“The situation was different when we used liquid bitumen, which is not really suitable for bonding. If you add 55% ocher, a malleable mass is formed,” explains Schmidt.

The mixture was just sticky enough for a stone tool to get stuck in it, but without sticking to the hands, making it a suitable material for a handle.

Indeed, a microscopic examination of the traces of wear on these stone tools revealed that the adhesives on Le Moustier’s tools were used in this way.

“The tools showed two types of microscopic wear: one is the typical polishing of sharp edges that is usually caused by working with other materials,” explains Iovita, who carried out this analysis. “The other is a glossy varnish distributed over the entire presumed hand-held part, but not elsewhere, which we interpreted as the result of abrasion of the ocher due to movement of the tool in the handle.”

The use of adhesives containing multiple components, including various sticky substances such as tree resins and ocher, was previously known among early modern humans, Homo sapiens, in Africa, but not among earlier Neanderthals in Europe.

Overall, the development of adhesives and their use in tool making is considered some of the best material evidence for the cultural evolution and cognitive abilities of early humans.

“Compound adhesives are considered one of the earliest expressions of modern cognitive processes still active today,” says Schmidt.

In the Moustier region, ochres and bitumens had to be collected remotely, which required a lot of effort, planning and a targeted approach, the authors note.

“Given the general context of the findings, we assume that this adhesive material was made by Neanderthals,” concludes Dutkiewicz.

“Our study shows that early Homo sapiens in Africa and Neanderthals in Europe had similar thought patterns,” adds Schmidt. “Their adhesive technologies are equally important to our understanding of human evolution.”