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The stone tool was attached to a handle made of liquid bitumen with 55 percent ocher added. It is no longer sticky and can be manipulated easily. Credit: Patrick Schmidt
Analysis of tools that are 40,000 years old has revealed a surprisingly sophisticated level of construction.
A team of researchers has discovered that Neanderthals made stone tools using a sophisticated multi-component glue. This discovery, the oldest known example of such an advanced adhesive in Europe, indicates that these early human relatives possessed a greater degree of intellectual and cultural sophistication than previously believed.
The work, published in the magazine Scientific advancesThey included researchers from New York University, the University of Tübingen, and the National Museums in Berlin.
Technical innovations of the Neanderthals
“These surprisingly well-preserved tools show a very similar technical solution to examples of tools made by early modern humans in Africa, but the exact recipe reflects a Neanderthal ‘turn’, which is the production of handles for portable tools,” says Radu. Iovita. , associate professor at New York UniversityCenter 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 Ewa Dutkiewicz from the Museum of Prehistory and Early History at the National Museums Berlin, re-examined previous finds from Le Moustier, an archaeological site in France that was discovered at the beginning of the 20th century.
Micrographs showing traces of wear on a tool used by Neanderthals during the Middle Paleolithic. The locations of the micrographs on the artifact are indicated in the drawing (top left) in red. a) Polish or polish the active edge of the tool handle. b) Polish under dye stains within the area covered by adhesive. c) Ridge between concave surfaces formed by the removal of pieces of stone that were removed, rather than naturally worn. d) Tarnished or worn cord in the grip area that was covered with an adhesive. A comparison of (c) and (d) indicates that the worn portion is within the area covered by the designed adhesive grip. Images are shown in microns. Credit: Drawing by D. Greinert, Staatliche Museen zu Berlin
The Le Moustier stone tools, used by Neanderthals during the Middle Paleolithic of the Mousterian, between 120,000 and 40,000 years ago, are preserved in the collection of the Museum of Prehistory and Early History in Berlin and had not previously been examined in detail. The tools were rediscovered during an internal review of the collection and their scientific value was recognized.
“The items were individually wrapped and intact from the 1960s,” Dutkiewicz says. “In this way, the adhered remains of organic substances were very well preserved.”
Discovering ancient technologies
The researchers discovered traces of a mixture of ocher and bitumen on various 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 is also found naturally in soil.
“We were surprised that the ocher content was over 50 percent,” says Schmidt. “This is because air-dried bitumen can be used unaltered 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.
Liquid bitumen and ocher earth pigment before mixing. Credit: Patrick Schmidt
“The situation was different when we used liquid bitumen, which is not very suitable for gluing. If 55 percent ocher is added, a malleable mass is formed,” says Schmidt.
The mixture was sticky enough for a stone tool to stay stuck in it, but not stick to the hands, making it a suitable material for a handle.
Importance of the findings
In fact, microscopic examination of the wear traces of 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 on sharp edges that generally occurs when working with other materials,” explains Iovita, who carried out this analysis. “The other is a bright glaze distributed over the entire part that is supposed to be held in the hand, but not elsewhere, which we interpret as the result of abrasion of the ocher due to the movement of the tool within the handle” .
Implications for human evolution
The use of adhesives with various components, including various sticky substances such as tree resins and ocher, was already known from the earliest times of modern man. Homo sapiens, in Africa, but not of the first Neanderthals in Europe. In general, the development of adhesives and their use in tool making is considered one of the best material evidence of the cultural evolution and cognitive abilities of early humans.
“Composite adhesives are considered one of the first expressions of modern cognitive processes that are still active today,” says Schmidt.
In the Le Moustier region, ocher and bitumen had to be collected from distant places, which required a lot of effort, planning and a specific approach, the authors note.
“Taking into account the general context of the findings, we assume that this adhesive material was made by Neanderthals,” concludes Dutkiewicz.
“What our study shows is 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.”
Reference: “Ochre-based composite adhesives at the Mousterian typographic site document complex cognition and high investment” by Patrick Schmidt, Radu Iovita, Armelle Charrié-Duhaut, Gunther Möller, Abay Namen and Ewa Dutkiewicz, February 21, 2024, Scientific advances.
DOI: 10.1126/sciadv.adl0822