A group of researchers has discovered the oldest remains of a complex adhesive in Europe, a type of glue that Neanderthals used to make stone tools.

The finding, published in the journal Science Advances , suggests that these close relatives of modern humans were more advanced than previously thought.

Researchers reexamined artifacts found in France at the beginning of the 20th century at a site known as Le Moustier, which had not been surveyed since the 1960s.

The tools in question were recently rediscovered during an inventory review at Berlin’s Museum of Prehistory and Early History.

“The objects had been individually wrapped and had not been touched since the 1960s. As a result, the organic remains stuck there had been very well preserved,” said researcher Ewa Dutkiewicz, one of the team leaders, in a statement.

In their analysis, the scientists found traces of ochre and bitumen, which together form a mixture sticky enough to adhere to stone tools, but not sticky to the hands, so it could be used as a handle.

It was already known that early humans in Africa used adhesive mixtures to make tools, but not that Neanderthals did the same in Europe.

“What our study shows is that early Homo sapiens in Africa and Neanderthals in Europe had similar thinking patterns,” said Patrick Schmidt, another of the researchers, who highlighted the importance of this idea for our understanding of human evolution.

Experts from New York University, the University of Tübingen, and the National Museums of Berlin participated in the study.