Neanderthals may have treated wounds with antibiotic sticky tar

Neanderthals may have used tar made from tree bark as an antiseptic to treat wounds. Modern experiments with birch tar show that it has antibiotic properties regardless of how it is made, suggesting that Neanderthals may have discovered its medicinal uses.

The finding adds to a growing body of evidence suggesting that Neanderthals used medicinal plants to treat injuries and illnesses.

“Birch tar as a substance has been known for quite some time from the late Pleistocene, specifically from Neanderthal sites across Europe,” he says Tjaark Siemssen at Oxford University.

“It’s pretty clear that it was used as an adhesive,” says Siemssen, for example to attach sharpened stone heads to wooden spears. However, he says that may not have been its only use. In some indigenous communities, birch tar has been applied as a healing salve in recent centuries. Among Mi’kmaq communities in eastern Canada, it is called maskwio’mi and is used as a broad-spectrum antibiotic.

To see if the birch tar produced by Neanderthals might have similar properties, Siemssen and his colleagues collected the bark of the downy birch (Betula pubescens) and silver birch (Betula pendula) on public land in Germany. They tried three methods of making birch tar.

In the “elevated structure” method, they dug a small hole and placed a container at the bottom. They piled birch bark on top of it and wrapped it in clay. They lit a fire on this pile and after 2 hours collected the birch tar that dripped into the container.

The second method was much simpler and may have been the first to be tried by the Neanderthals. The team burned a small amount of birch bark under the firestone, causing the birch tar to condense on the stone. This “condensation” method produced much smaller quantities.

Finally, for comparison, the researchers tried a modern method used by Mi’kmaq communities. They heated birch bark in a sealed metal container with holes punched in the bottom to allow the tar to drip out.

All birch tars were tested for antimicrobial activities. All but one were effective against Staphylococcus aureusa bacterium that is often found in skin infections. The most powerful was the one made from white birch using the raised structure method. The only one that didn’t block S. aureus it was made from birch using the felt condensation method.

The experiment suggests that birch tar has persistent antimicrobial properties even when produced using low-tech methods that would have been available to Neanderthals, Siemssen says. While Neanderthals used it as an adhesive, “to reduce the use case to a single thing when it has so many different purposes is potentially quite misleading,” he says.

“I appreciate that the authors have identified some medicinal value in birch bark,” he says Karen Hardy at the University of Glasgow in Great Britain. However, Hardy points out that many plants have medicinal properties without the need for processing. “Getting pitch from birch bark is a complex and time-consuming process,” he says. “I think to prove their argument that it was made intentionally for its healing properties, they would have to show its superior or unique value.

Previous research has identified additional evidence that Neanderthals used medicinal plants. One Neanderthal with a dental abscess appears to have eaten plants with pain-relieving and anti-inflammatory properties. Hardy and his colleagues found evidence that Neanderthals ate yarrow and chamomile: plants that have medicinal uses but no nutritional value.

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