It’s been known that early modern humans, the Homo sapiens, in Africa could concoct a glue using various components, but that could not be said for Neanderthals, our ancient cousins, living in Europe.
Using adhesives to make tools is one of the strongest proofs of how early humans developed their culture and thinking abilities.
And in a nod to Neanderthals’ cognitive abilities and cultural sophistication, a team of researchers has recently unveiled evidence that these archaic humans did in fact craft stone tools using a sophisticated multi-component adhesive.
"This study suggests Neanderthals' cognitive processes resembled those of early Homo sapiens, shedding new light on human evolution," said Patrick Schmidt, co-author of the study.
How did they find out?
It was a chance encounter when the team revisited artifacts from Le Moustier, a French archaeological site, uncovering stone tools dating back to the Middle Palaeolithic Mousterian period, between 120,000 and 40,000 years ago.
The meticulously preserved artifacts, stored since the 1960s, revealed traces of a mixture comprising ochre and bitumen - a natural asphalt component - on tools like scrapers and blades.
The discovery astonished researchers, especially the high ochre content, which surpassed 50 percent, altering the adhesive's properties.
“We were surprised that the ochre content was more than 50 percent,” said Schmidt. “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.”
Further tests showed its suitability for tool handles, remaining sticky but not adhering to hands.
“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 Radu Iovita, who conducted a microscopic examination of the tools.
Cultural evolution and cognitive abilities
Microscopic analysis unveiled unique wear patterns consistent with stone tool usage, confirming the adhesive's practical application.
“The tools showed two kinds of microscopic wear: one is the typical polish on the sharp edges that are generally caused by working other materials,” explained Iovita.
“The other is a bright polish distributed all over the presumed hand-held part, but not elsewhere, which we interpreted as the results of abrasion from the ochre due to movement of the tool within the grip,” she added.
The effort made by Neanderthals to procure materials from distant locations implies advanced planning and cognitive abilities.
Making compound adhesives was one of the earliest signs that early humans had smart brains. These abilities they showed are still seen in people today.
However, a recent study published in Nature reveals that Homo sapiens lived in Northern Europe alongside Neanderthals around 45,000 years ago. That means that they co-existed.
Archaeologists found evidence of this coexistence through genetic analysis of bone fragments from the Ilsenhohle cave site in Germany, reported Interesting Engineering.
This discovery emphasizes a lengthy overlap between the two species, lasting thousands of years until the extinction of Neanderthals. Could it be that the adhesive-laden stone tools found do indeed belong to Homo sapiens?
The new study, published in the journal Science Advances, involved scientists from New York University, the University of Tubingen, and the National Museums in Berlin.
