Neanderthal caveman hunt a bear about 500,000 years ago in this artist's conception. Three Lions/Getty Images

Neanderthals are often overlooked as early members of the genus Homo from Europe and Asia who were just a stepping stone in the formation of the more evolved Homo Sapien.

Now scientists have discovered the complex process by which Neanderthals made tar from birch tree bark, belying the lowly simpleton image associated with our ancestors.

The tar which was used as an adhesive to join spear points to handles, is considered an important step in human knowledge and which furthered our dominance over the food chain.

Scientists already knew of tar-coated stones dating from at least 200,000 years ago at Neanderthal sites in Europe. That discovery had surprised many as till then humans (Homo Sapiens) in Africa were credited with the discovery of adhesives some 70,000 years ago, as the process was a high-tech skill associated with anatomically modern humans.

Now, a research by archaeologist Paul Kozowyk of Leiden University in The Netherlands and his colleagues published in the journal Scientific Reports not only supports that Neanderthals invented adhesives, but also explains how they probably achieved the feat.

The team analyzed all the excavated evidence for early tar production, and conducted experiments on these samples to determine how early humans and Neanderthals used this tar and plant fibres to make a waterproof, adhesive coating to attach sharpened bone or flint to wooden/ bone handles to make tools.

These tools magnified their hunting skills, and played an important part in the evolution of humans.

The researchers have proposed three tar production methods that could have been developed by Neanderthals. They tried out all three production methods which ranged from the simple to the complex —from an ash mound on the ground to a raised structure padded with dirt to improve tar production.

The viability of the methods was checked by determining if Neanderthals had enough raw materials and the necessary tools needed for the setup.

“Our results indicate that it is possible to obtain useful amounts of tar by combining materials and technology already in use by Neanderthals,” said the report.

Experiments indicated that Neanderthals likely began producing tar by rolling the bark in hot ashes. Repeating this process could produce the quantities of tar seen in archaeological records.

They could have noticed patterns when they burnt food or just observed that certain materials such as birch wood collected tar when partially burnt,

“Neanderthals must have been able to recognize certain material properties, such as adhesive tack and viscosity,” the team wrote.

“What this paper reinforces is that all of the humans that were around 50,000 to 150,000 years ago roughly, were culturally similar and equally capable of these levels of imagination, invention and technology,” explained Washington University anthropologist Erik Trinkaus, in an interview with Gizmodo.

In order for tar production to become a perennial innovation and be used as frequently as our estimates suggest, Neanderthals must have been able to maintain the process of dry distillation as a useful technique for producing adhesives.

This diligence points to high levels of planning and intellect in our predecessors, raising questions about their eventual extinction.