Quirks & Quarks

Three ways Neanderthals made glue from birch bark

Neanderthals made glue from birch bark to keep their stone tools together two-hundred thousand years ago.
('Kozowyk et al. Scientific Reports')

The discovery
The excavation of two Neanderthal sites in Europe revealed that these early humans knew how to make glue from birch bark. In 2002, archaeologists found what has been described as two small  'lumps' of black tar at a 40,000 year old Neanderthal site in Germany. One included the impression of a stone tool, the other included a Neanderthal thumb print.  Four years later, similar tar was found at a much older Neanderthal site - dating back 200,000 years - in Italy. In this case the tar was still attached to a stone tool. Researchers determined that the tar at both sites was distilled from birch bark and used as glue for holding various stone tools together.

The experiment
Using methods and materials known to Neanderthals, scientists including Canadian Ph.D candidate Paul Kozowyk at Leiden University in the Netherlands, did some "experimental archaeology" to figure how the glue was made. They set up three different methods for distilling the tar from the birch bark. They key was to heat the bark without completely burning it, so that the dripping tar could be contained for use as glue. In its hardened state, Neanderthal glue was then subjected to modern adhesive impact tests and performed remarkably well. 

Why is this significant?
The traditional thinking has been that Neanderthals were mentally inferior to modern Homo Sapiens, but this study adds to a growing amount of research that suggests a much higher level of sophistication than previously thought. Neanderthals were the first to make glue, one of humanity's oldest technical innovations.