For decades, the sticky black tar that Neanderthals cooked out of birch bark has been filed away in the archaeological literature as prehistoric glue. A new round of laboratory experiments suggests that label is far too narrow. Researchers in Germany, Britain, Belgium and Canada made birch tar using methods reconstructed from Middle Palaeolithic sites, then tested it against bacteria, and every sample inhibited Staphylococcus aureus, the organism behind many infected wounds. The work, published in PLOS One, was led by Tjaark Siemssen of the University of Cologne and the University of Oxford.
A Glue That Did Much More Than Stick
Birch tar is found at Neanderthal sites across Europe, often still clinging to stone tools. It was made by heating birch bark under low-oxygen conditions, a process called dry distillation, and used to bind flint points to wooden shafts, a technique known as hafting. Ancient Origins has previously reported on the discovery of a 65,000-year-old Neanderthal tar distillation oven in Gibraltar, a purpose-built hearth for extracting tar from resin-rich plants.
But the picture has been widening. Traces of chamomile and yarrow in Neanderthal dental calculus, and the careful planning revealed by stone tools carried across the landscape, point to people who knew and used medicinal plants. Indigenous communities in northern Europe and Canada still use birch tar on wounds, which prompted Siemssen's team to ask whether the same material had a second life in the Ice Age.
Recreating an Ice Age Chemistry Set
To find out, the researchers harvested bark from silver birch and downy birch, the species that grew across Pleistocene Europe. One method followed a Mi'kmaq tradition from eastern Canada, in which bark is packed into a pierced tin and heated so that tar drips into a container below. A second used a raised clay structure built over a buried pot. A third relied on tar vapor condensing against a cool stone surface, a technique thought to belong to the earliest stages of tar production.
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Birch bark pitch produced in a single sealed pot, the same material Neanderthals made by dry distillation. (Jorre / CC BY-SA 3.0)
The experiments were messy, and the authors made no attempt to hide it. "Every step of the production is a sensory experience in itself, and getting the tar off our hands after spending hours at the fire has been a challenge every time," they admitted in a statement. The study was a collaboration with Cape Breton University in Canada, where researchers work with Mi'kmaq knowledge holders on birch bark medicine.
What the Bacteria Revealed
Every sample inhibited S. aureus, with zones of inhibition running from about 7 to 10.5 millimeters. The strongest result came from tar made with silver birch bark using the raised structure method, while one downy birch sample showed no activity at all. The same tars had no measurable effect on Escherichia coli, a Gram-negative bacterium whose outer membrane blocks many plant compounds.
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The likely culprits are phenolic compounds such as catechols and guaiacols, which earlier chemical work has tied to birch tar's antimicrobial punch. The results also chime with Mi'kmaq use of maskwio'mi, a birch bark ointment applied to skin infections, and with Saami practice in Lapland. As Siemssen put it, the findings suggest that "antimicrobial properties played a role as far back as the time of the early Neanderthals."
Distilling birch bark in a pierced tin in Cape Breton (Unama'ki), Nova Scotia, following a Mi'kmaq method used to make maskwio'mi ointment. (Nicolaas Honig / PLOS One/CC BY 4.0)
Ancient Remedies and the Modern Antibiotic Crisis
The authors are careful not to overclaim. Inhibiting bacteria on an agar plate does not prove Neanderthals dabbed tar on their wounds, and birch tar contains compounds, including polycyclic aromatic hydrocarbons, that would need safety testing before any medical use. Karen Hardy of the University of Glasgow told Smithsonian Mag that tar production was a complex, time-consuming procedure, and that proving deliberate medicinal use would require showing birch tar had a unique advantage over other remedies.
Still, the researchers argue the question deserves pursuit, especially as ancient remedies keep feeding modern drug research while antibiotic resistance tightens its grip. Similar disputes have followed other claims about Neanderthal behavior, including the long-running argument over the burials at Shanidar Cave in Iraq.
"Our findings show that it might be worthwhile to examine targeted antibiotics from ethnographic contexts, or, as in this case, from prehistoric contexts, in greater depth," Siemssen said.
Top image: Researchers used methods that Neanderthals also used to produce birch tar and to analyze its antibacterial properties. Source: Tjaark Siemssen/PLoS ONE
By Gary Manners
References
Archaeology Magazine. 2026. Neanderthals May Have Used Birch Tar to Treat Wounds. Available at: https://archaeology.org/news/2026/03/24/neanderthals-may-have-used-birch-tar-to-treat-wounds/
EurekAlert. 2026. Neanderthals may have used birch tar for its anti-bacterial properties. Available at: https://www.eurekalert.org/news-releases/1119603
ScienceDaily. 2026. Neanderthals may have used prehistoric glue as an ancient antibiotic. Available at: https://www.sciencedaily.com/releases/2026/10/261008005256.htm
Siemssen, T., Oludare, A., Schemmel, M., Puschmann, J., Bierenstiel, M. 2026. Antibacterial properties of experimentally produced birch tar and its medicinal affordances in the Pleistocene. PLOS One. Available at: https://doi.org/10.1371/journal.pone.0343618
Smithsonian Magazine. 2026. Did Neanderthals Use Birch Bark Tar as an Antibiotic to Treat Wounds and Infections? Available at: https://www.smithsonianmag.com/smart-news/did-neanderthals-use-birch-bark-tar-as-an-antibiotic-to-treat-wounds-and-infections-180988393/
