For tens of thousands of years, Neanderthals worked with birch tar. They used it to bind spear points to wooden shafts, creating composite tools that gave them a hunting advantage across Ice Age Europe. Now, researchers suggest the sticky black substance may have served another, more intimate purpose: treating their injuries and infections.
According to a study published March 18, 2026 in the journal PLOS One by researchers led by Tjaark Siemssen of the University of Cologne and the University of Oxford, Neanderthals probably used birch tar for multiple functions, including treating their wounds. The finding emerges from experimental work testing what ancient peoples may have known through observation and trial.
The research team extracted tar from modern birch species known to grow in Neanderthal-inhabited areas and tested it against samples of Staphylococcus aureus and Escherichia coli, common bacteria. All of the tar samples were effective at hindering the growth of Staphylococcus bacteria known to cause wound infections, though the tar showed no effect against E. coli. The effectiveness varied depending on the birch species and tar concentration, with silver birch producing the strongest results.
This finding aligns with long-standing practice. Indigenous communities in northern Europe and Canada use birch tar to treat wounds, and there is growing evidence that Neanderthals also employed a variety of medical practices. The researchers themselves experienced the substance's pervasive nature during their work. As they noted in their paper, contamination of the skin during tar handling proved nearly inevitable, suggesting Neanderthals could have discovered medicinal properties simply through repeated exposure to their working material.
The active compounds are phenolic derivatives, molecules that exist in many plants and form the basis of modern antiseptics and disinfectants. Terpenes and terpenoids, which protect plants from insect damage and fungal infection, likely contribute as well. Understanding exactly which compounds and proportions prove most effective could hold relevance for modern medicine, particularly as antibiotic resistance grows worldwide.
The broader picture shows Neanderthals as careful observers of material properties. Indigenous communities in northern Europe and Canada treat wounds with birch tar and there is growing evidence that Neanderthals employed a variety of medical practices, including helping their sick or injured comrades. Dental remains from archaeological sites have revealed traces of chamomile and yarrow, herbs with anti-inflammatory properties, suggesting sophisticated understanding of plant-based remedies.
The question of how much Neanderthals understood remains open. The study cannot prove they deliberately applied tar to wounds or that they grasped the concept of infection prevention. What it does establish is that birch tar would have worked if they tried it, and that repeated use of the substance made accidental skin contact inevitable. Once noticed, its soothing or healing effects might have encouraged further application, as Indigenous peoples continued to do across the centuries.
Researchers emphasise that this work sits within a broader reassessment of Neanderthal life. Recently, some researchers have raised the question of whether Neanderthals had multiple uses for this substance, and there is growing evidence that Neanderthals also employed a variety of medical practices. Other discoveries have documented spun plant-fiber yarn and wooden foraging tools, evidence of cultural practices far removed from the image of dim, brutish creatures that dominated older scientific thinking.
The study offers a humbler lesson: sometimes the most important discoveries are the ones that reveal how well-adapted our ancestors were to their world, using the materials at hand to solve the problems of survival.