A sticky solution: Know how Neanderthals made the world's first glue

Neanderthals made the world's oldest known glue 200,000 years ago by extracting tar from birch bark, scientists have found.

A Neanderthal spear is predominantly made up of two parts, a piece of flint for the point, and a stick for the shaft.

However, one aspect is often overlooked, and has recently been puzzling archaeologists: the glue that fixes the point to the shaft.

For this, Neanderthals used tar from birch bark, a material that researchers often assumed was complex and difficult to make.

Archaeologists have now shown that this assumption was unfounded. Led by Paul Kozowyk and Geeske Langejans, the researchers from University of Leiden in The Netherlands discovered no fewer than three different ways to extract tar from birch bark.

For the simplest method, all that is needed is a roll of bark and an open fire. This enabled Neanderthals to produce the first glue as early as 200,000 years ago.

The researchers made this discovery by setting to work with only the tools and materials that Neanderthals possessed.

They used experimental archaeology because the preservation of ancient adhesives is incredibly rare and there is no direct archaeological evidence about how tar was made during the Palaeolithic.

"In earlier experimental attempts, researchers only managed to extract small quantities of tar from birch bark, or they didn't get anything at all," said Kozowyk.

"It was beleived that this was because the fire needed to be controlled to within a narrow temperature range. However, we discovered that there are more ways to produce tar, and that some work even with a significant temperature variation," he said.

Researchers showed that Neanderthals discovered tar production by combining existing knowledge and materials.

Neandertals may have started with a simple method that required only fire and birch bark, and later adopted a more complex method to obtain higher yields of tar.