A team of scientists has discovered that Neanderthals made stone tools that were held together with a multi-component adhesive. The findings, which are the first evidence of a complex adhesive in Europe, suggest that these predecessors to modern humans had more cognitive and cultural development than previously thought.

Work, reported in the journal Advances in scienceResearchers from New York University, the University of Tübingen, and the National Museum in Berlin were involved.

“These surprisingly well-preserved tools show a technological solution that is similar to examples of tools made by early modern humans in Africa, but the exact recipe reflects a Neanderthal ‘spin,’ which is the production of grips for handheld tools,” says Radu Iovita. An associate professor at New York University’s Center for the Study of Human Origins.

The research team, led by Patrick Schmidt from the Early Prehistory and Quaternary Ecology Section of the University of Tübingen and Eva Ditkiewicz from the Museum of Prehistory and Early History of the National Museums of Berlin, visited an archaeological site at Le Moustier. Re-examined previous findings from France which was discovered in the early 20th century.

The stone tools of Le Moustier — used by Neanderthals between 120,000 and 40,000 years ago during the Mousterian Middle Archaic period — are housed in the Museum of Prehistory and Prehistory in Berlin, and their earlier was not reviewed in detail. The tools were rediscovered during an internal review of the collection and their scientific value was recognized.

“From the 1960s the objects were individually wrapped and not touched,” says Dutkiewicz. “As a result, the remains of organic matter were very well preserved.”

The researchers discovered traces of goiter and bitumen compounds on several stone tools, such as scrapers, flakes and blades. Ocher is a naturally occurring earth pigment. Bitumen is a component of asphalt and can be made from crude oil, but it also occurs naturally in soil.

“We were surprised that the gather content was more than 50 percent,” Schmidt says. “This is because air-dried bitumen can be used as an adhesive without modification, but when such a large proportion of gero is added it loses its adhesive properties. “

He and his team tested these materials in tensile tests — used to determine strength — and other measures.

“It was different when we used liquid bitumen,” Schmidt says.

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

Indeed, microscopic examination of the wear marks on these stone tools revealed that the adhesives on the Le Mostier tools were used in this way.

“The tools showed two types of microscopic wear: one is normal polishing on sharp edges that is usually caused by other materials being worked on,” explains Iovita, who conducted the analysis. “The other is a bright polish distributed all over the hand grip, but nowhere else, which we interpreted as the result of frictional abrasion caused by tool movement within the grip.”

The use of multi-component adhesives, including various adhesives such as tree resins and ocher, was first known by modern humans. A wise man, in Africa but not from earlier Neanderthals in Europe. Overall, the development of adhesives and their use in the manufacture of tools is considered the best material evidence of the cultural evolution and cognitive abilities of early humans.

“Compound adhesives are considered among the first expressions of modern cognitive processes that are still active today,” Schmidt says.

The authors note that in the Le Moustier area, gero and bitumen had to be collected from remote locations, which meant a lot of effort, planning and a targeted approach.

“Taking into account the overall context of the food, we assume that this adhesive material was made by Neanderthals,” Dutkiewicz concluded.

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

The University of Tübingen contributed content to this story.