Neanderthals’ Ancient Medicine Cabinet: Birch Tar’s Antibacterial Power Revealed

International research led by the University of Cologne has demonstrated that birch tar, a material traditionally associated with Neanderthal toolmaking, possesses antibacterial properties that these hominids may have intentionally used to treat wounds. The findings, published in the journal PLOS One, offer a latest perspective on the medical capabilities of our extinct human relatives.

Birch Tar: More Than Just Glue?

The research team, comprised of scientists from the University of Cologne, the University of Oxford, the University of Liège, and Cape Breton University in Canada, analyzed the antimicrobial potential of birch tar using production techniques archaeologically plausible for Neanderthals. Birch tar is a viscous substance obtained from birch bark, and its remains are frequently found at Middle Paleolithic European sites. Traditionally, archaeologists believed these finds indicated its leverage as an adhesive for stone tools—a process involving attaching different pieces to create composite implements.

However, new ethnographic data combined with growing evidence of medicinal behaviors and plant use by Neanderthals prompted researchers to reconsider the material’s functions. As Tjaark Siemssen, from the universities of Cologne and Oxford and the study’s first author, explains, “New studies suggest that birch tar could have been used for other purposes. Ethnographic findings in global contexts show that it also has medicinal applications. As there is increasing evidence of medical behaviors and plant use among Neanderthals, we were interested in exploring birch tar in this context.”

Recreating Neanderthal Tar Production

To investigate, scientists experimentally produced tar using two methods documented in the archaeological record. The first involved burying birch bark in a sealed pit and burning it in an oxygen-limited environment—a dry distillation process that decomposes the bark without complete combustion, leaving tar as a residue. The second method replicated burning the bark on a hard surface, like stone, allowing the product to condense during burning. Both methods utilized birch species present in Pleistocene Europe, ensuring the samples mirrored those available to Neanderthals.

Significant Antibacterial Activity

Laboratory analysis of the experimental samples revealed that all birch tar produced using Neanderthal methods significantly inhibited the growth of Staphylococcus aureus, a pathogenic bacteria central to wound infections and known for its increasing resistance to antibiotics. This antibacterial efficacy was consistent across all samples, regardless of the production method, suggesting the antimicrobial properties are inherent to the material itself.

The authors propose that the availability and medicinal qualities of birch tar may have been recognized and utilized by Neanderthal groups. “The findings indicate that antimicrobial properties already played a role in the time of the first Neanderthals and could be used intentionally,” Siemssen states.

Implications for Modern Medicine

The study’s relevance extends beyond archaeology. The global rise of antibiotic-resistant bacteria necessitates exploring new pharmacological sources. Investigating compounds with antimicrobial properties found in ethnographic and prehistoric contexts, as this research demonstrates, may open avenues for developing new therapeutic agents.

Siemssen concludes, “Our results show that it may be worth examining in more depth specific-acting antibiotics from ethnographic contexts or, as in this case, also from prehistoric contexts.”

This research provides experimental evidence of Neanderthal medical capabilities and bridges experimental archeology with contemporary pharmacology, suggesting knowledge of natural resource healing properties may be far older than previously thought. A related study from the University of Cologne, published in PLOS One in December 2025, modeled the transition from Neanderthals to modern humans in Europe, analyzing potential interactions between the two groups on the Iberian Peninsula.