Washington, May 12 (ANI): Stone Age humans who lived about 70,000 years ago were such good chemists that they made a sophisticated kind of natural glue by tweaking the chemical and physical properties of an iron-containing pigment, known as red ochre, with the gum of acacia trees for their shafted tools, according to a study.
While it has long been believed that the blood-red pigment served a decorative or symbolic purpose, scientists also suspected that the pigment might have been purposely added to improve glue that held the peoples' tools together.
With a view to testing this idea, researchers at the University of the Witwatersrand in Johannesburg, South Africa, recreated the ancient glue using only Stone Age materials and technologies.
The results showed that glue containing red ochre was less brittle and more shatterproof than glue made from acacia gum alone.
"We discovered that when we used ochre, the glue is much more robust, and the stone tool doesn't come off the shaft," National Geographic News quoted study team member Lyn Wadley as saying.
The researchers also believe that making the glue was mentally taxing work that would have needed the ancient people to account for differences in the chemistry of gum harvested from different trees, and in the iron content of ochre from different sites.
"They couldn't possibly have known about chemical pH or iron content ... but they knew that certain combinations of things worked very well," Wadley said.
She further said that the intelligence of Stone Age humans was more akin to that of modern humans than previously thought.
"Our study shows that there's a lot of overlap between ourselves and these ancient people. Their technology was a lot more competent than we have given them credit for."
A research article on this work has been published in the journal Proceedings of the National Academy of Sciences. (ANI)