Archaeologists have found traces of ancient ochre-based multicomponent adhesives on 40,000-year-old stone tools from Le Moustier, France.
“These astonishingly well-preserved tools showcase a technical solution broadly 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,” said Dr. Radu Iovita, a researcher with the Center for the Study of Human Origins at New York University.
In the research, Dr. Iovita and colleagues examined stone tools with traces of red and yellow colorants from Le Moustier, an archaeological site in France that was discovered in the early 20th century.
These stone tools were created by Neanderthals during the Middle Paleolithic period between 120,000 and 40,000 years ago.
They are kept in the collection of Berlin’s Museum of Prehistory and Early History and had not previously been examined in detail.
“The items had been individually wrapped and untouched since the 1960s. As a result, the adhering remains of organic substances were very well preserved,” said Dr. Ewa Dutkiewicz, a researcher with Berlin’s Museum of Prehistory and Early History.
The researchers found traces of a mixture of ochre and bitumen on several Mousterian stone tools, such as scrapers, flakes, and blades.
Ochre is a naturally occurring earth pigment; bitumen is a component of asphalt and can be produced from crude oil, but also occurs naturally in the soil.
“We were surprised that the ochre content was more than 50%. This is because air-dried bitumen can be used unaltered as an adhesive, but loses its adhesive properties when such large proportions of ochre are added,” said Dr. Patrick Schmidt, a researcher at the University of Tübingen.
The scientists examined these materials in tensile tests — used to determine strength — and other measures.
“It was different when we used liquid bitumen, which is not really suitable for…
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