Birch bark was heated in underground chambers to create a tougher adhesive.
Neanderthal tools might look relatively simple, but new research shows that Homo neanderthalensis devised a method of generating a glue derived from birch tar to hold them together about 200,000 years ago—and it was tough. This ancient superglue made bone and stone adhere to wood, was waterproof, and didn’t decompose. The tar was also used a hundred thousand years before modern humans came up with anything synthetic. After studying ancient tools that carry residue from this glue, a team of researchers from the Eberhard Karls University of Tübingen and other institutions in Germany found evidence that this glue wasn’t just the original tar; it had been transformed in some way. This raises the question of what was involved in that transformation. To see how Neanderthals could have converted birch tar into glue, the research team tried several different processing methods. Any suspicion that the tar came directly from birch trees didn’t hold up because birch trees do not secrete anything that worked as an adhesive. So what kind of processing was needed? Each technique that was tested used only materials that Neanderthals would have been able to access. Condensation methods, which involve burning birch bark on cobblestones so the tar can condense on the stones, were the simplest techniques used—allowing bark to burn above ground doesn’t really involve much thought beyond lighting a fire. The other methods involved a recipe where the bark was not actually burned but heated after being placed underground. Two of these methods involved burying rolls of bark in embers that would heat them and produce tar. The third method would distill the tar. Because there were no ceramics during the Stone Age, sediment was shaped into upper and lower structures to hold the bark, which was then heated by fire. Distilled tar would slowly drip from the upper structure into the lower one. The resulting tars were all put through chemical and molecular analysis, as well as micro-CT scans, to determine which came closest to the residue on actual Neanderthal tools. Tars synthesized underground were closest to the residue on the original artifacts. “[Neanderthals] distilled tar in an intentionally created underground environment that restricted oxygen flow and remained invisible during the process,” the researchers wrote. “This degree of complexity is unlikely to have been invented spontaneously.”
“Every time I go to the dentist, I think about that guy,” researcher says.
The world’s first dentist was a Neanderthal, according to a recent study. 59,000 years ago in what’s now southwestern Siberia, a Neanderthal had a toothache. It must have been a doozy because they were desperate enough to sit still while someone drilled into the tooth with a sharp stone tool, removing the infected tissue and ultimately relieving the pain. The process left behind a hole in the tooth that paleoanthropologist Alisa Zubova of the Russian Academy of Sciences and her colleagues recognized, tens of millennia later, as dental work. Archaeologists unearthed the tooth at Chagyrskaya Cave in Russia, and it’s now the oldest known evidence of dentistry—or any direct medical treatment.
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To test whether the hole was made intentionally, Zubova and her colleagues examined the tooth more closely with scanning electron microscopes, micro-CT, and Raman spectroscopy, a technique for identifying the chemical makeup of an object. They also made their own stone drilll or perforator (a sharp stone tool that would have been used to drill or punch holes in hides, bone, and other materials) and tested it on three human teeth. Two of the teeth were museum specimens, whose age and context curators didn’t know, making them less useful for other kinds of research. But one, an upper left third molar with an untreated cavity, came straight from the mouth of one of the authors—for science! (In most scientific papers, a section at the end outlines the specific contributions of each author, which usually means tasks like writing, data collection, production of stone tools, and analysis. This paper’s author contributions did not list “donation of a tooth for experimental archaeology,” so we can only speculate about who bit the proverbial bullet.) The holes and striations left behind by Zubova and her colleagues’ experiments very closely matched what they saw on the molar from Chagyrskaya, which means it’s very likely that the 59,000-year-old tooth was, in fact, the aftermath of an actual Paleolithic medical procedure.
