September 5, 2017

Researchers reveal how Neanderthals made the first glue

Long before modern man discovered the first glue, Neanderthals were using tar made from tree bark as an adhesive to craft weapons and other tools, according to a new study led by researchers from the Netherlands and published in a recent edition of the journal Scientific Reports.

In fact, as Ars Technica explained, lead investigator Paul Kozowyk, an archaeologist at Leiden University, and his colleagues found that Neanderthals were distilling tar for use in various tools as far back as 200,000 years ago, or 150,000 years before the first Homo sapiens even arrived in Western Europe!

According to Seeker, Kozowyk’s team analyzed archaeological evidence and conducted a series of experiments before determining that these archaic humans were able to invent tar and use it as an adhesive to affix handles to bone or stone tools, as well as to create improved spears and other types of weapons used for hunting.

The question is: how did they manage to pull off such a feat? After all, as Ars Technica pointed out, modern methods of tar production require it to be distilled at temperatures of 340 degrees to 370 degrees Celsius in a ceramic vessel – a difficult feat for the Neanderthals, given that ceramic was not even invented until approximately 20,000 years ago.

Based on their analysis, Kozowyk and his colleagues determined that they likely used a method known as dry distillation to create tar. This method, Popular Mechanics explained,  would have involved placing oak or birch bark into a fire to generate gases that would condense into tar.

Three possible techniques could have produced the adhesive

Even so, the Neanderthals still would have required some type of container in which to collect the gases and hold the tar, the publication added. The researchers tested various techniques using only the tools and technology that the ancient hominids would have possessed, and determined that there were three possible ways in which such a feat could have been accomplished.

The first possible technique, the “ash mound” method, involved heating bark under a pile of ash and embers, then gathering the emissions in a birch bowl. The second possible technique, the “pit roll” method, involved inserting a roll of bark into a narrow pit, then lighting the top on fire. This would have caused tar to drip onto a rock located on the bottom of the pit.

Finally, the third possible technique – the “raised structure” method – would have involved using a bowl made of birch. The bowl would have been placed in a shallow pit and covered over with a screen made from green willow wood, the researchers explained. The bark would have then been placed on top of the screen, buried and set in fire, slowly burning the bark and creating tar.

Kozowyk’s team reported that any of these methods would have produced a few grams of tar, even if the temperatures dipped below 200 degrees Celsius, and would not have required ceramic containers. Furthermore, they surmise that Neanderthals may have created tar by accident at first, then realizing its usefulness after touching it and becoming aware that it was sticky.

“It's possible that all three methods we tested, or even some different methods, were used depending on the needs or requirements at the time... My personal favorite is the pit roll method, because it's simple, but still produced reasonable quantities of tar,” Kozowyk said in an interview with Seeker. While tar was eventually used for many purposes, he added, it is “unlikely” that the Neanderthals used it for anything other than tool fabrication.


Image credit: Paul Kozowyk