Tar very much

Playing with fire reveals how Neanderthals were able to fix handles to their cutting blades.

In 2005, in an Italian quarry, palaeontologists unearthed some stone flakes – cutting blades – near ancient bones of mice and a small elephant.

The animal remains dated to the Middle Pleistocene – 781,000 to 126,000 years ago. The flakes were covered in a black tar made from birch bark. This meant the artefacts could not have been more than 200,000 years old – in line with the earliest recorded tar ever discovered.

Making tar needs time and temperature management: thought to be impossible without the use of ceramic containers – yet none were found.

There was an even more interesting matter. When the tar was made, Homo sapiens were not in the region. Neanderthals were, however, and had therefore worked out how to make tar without ceramics. The discovery prompted fresh speculation about Neanderthal cognition. Before one can make tar, after all, one first has to imagine it – and conceive a use for it.

Research by a team led by Paul Kozowyk of Leiden University in the Netherlands might have an answer as to where the tar came from.

In a paper published in the journal Scientific Reports, Kozowyk and colleagues describe methods to produce tar from birch bark, using only materials that were available during the Middle Pleistocene.

The most successful involved digging a pit into which a birch bark container was placed. The pit was covered with a makeshift organic mesh topped with loose sheets of bark. It was then covered with earth, and a fire set below it.

“This method resulted in the most variable output of tar, but when successful it gave the highest yields by a large margin,” the scientists report. Their best attempt produced almost 16 grams of tar from 100 grams of bark. Repeating the process would produce enough tar to make tools of the type found at Neanderthal excavation sites.

Kozowyk’s team also found making tar this way was a forgiving proces: “A ceramic container is not required, and temperature control need not be as precise as previously thought,” they write.

Making tar, they note, implies the early human had a high level of intelligence: “Neanderthals must have been able to recognise certain material properties, such as adhesive tack and viscosity.”