Neanderthals may have used birch tar as more than just glue; it could have helped them ward off infection and even insect bites. People from several modern Indigenous cultures, including the Mi’kmaq of eastern Canada, use tar from birch bark to treat skin infections and keep wounds from festering. We know from several archaeological sites that Neanderthals also knew how to extract birch tar and that they used it as an adhesive to haft weapons. A recent study tested distilled birch tar against the bacteria S. aureleus and E. coli and found that Neanderthals could easily have used the same material as medicine for their frequent injuries. This is the simplest step-by-step tutorial for making birch tar: find a tree, set some bark on fire, get messy hands. Credit: Tjaark Siemssen, CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/) Medicine can be messy What we call “birch tar” in English has a lot of other names in multiple Indigenous languages, and it can range from an oily fluid to a brittle, almost solid tarry resin, depending on how long you heat it in the open air after extracting it from the bark. The Mi’kmaq of eastern Canada prefer the more fluid version, which they call maskwio’mi, for wound dressings and skin ointment. To test how well birch tar fends off common bacteria, the team gathered up rolls of bark from birch trees, choosing species that had been found at Neanderthal sites. They tested a few different methods to extract the sticky resin, or tar, from the bark. The simplest involved burning a roll of birch bark next to, or underneath, a flat rock, so the resin collects on the underside of the rock; the most efficient requires heating the roll of bark in a clay vessel buried inside a mound of dirt. Another method, popular with some modern Indigenous peoples, uses a tin can instead of a clay bowl. A team led by archaeologist Tjaark Siemssen, of the University of Cologne and the University of Oxford, tested the resulting sticky mess against cultures of Staphylococcus aureus—best known for its role in skin infections and its evolution of the antibiotic-resistant MRSA strain—and the gut bacterium Escherichia coli, a frequent culprit in food poisoning.