Washington: Prehistoric humans were using a highly skilled method to craft sharp-edged stone tools some 75,000 years ago in Africa, over 50,000 years earlier than previously thought, according to a new study.
It has been assumed that the advanced tool-sharpening technique known as pressure-flaking, in which stone pieces were sharpened by using pressure, was invented by Europeans some 20,000 years ago.
But researchers from the University of Colorado found the same delicate technology being used in sharpening the stone weapons discovered from Blombos Cave in South Africa dating from the Middle Stone Age, some 75,000 years ago.
According to the researchers, the tools had been made by pressure flaking, whereby a toolmaker would typically first strike a stone with hammer-like tools to give the piece its initial shape, and then refine the blade`s edges and shape its tip.
Study co-author Paola Villa, a curator at the University of Colorado Museum of Natural History, said the technique provides a better means of controlling the sharpness, thickness and overall shape of two-sided tools like spearheads and stone knives.
"Using the pressure flaking technique required strong hands and allowed toolmakers to exert a high degree of control on the final shape and thinness that cannot be achieved by percussion," Villa was quoted as saying by the Discovery News.
"This control helped to produce narrower and sharper tool tips."
To arrive at their conclusion that prehistoric Africans could have been the first to use pressure flaking to make tools, the researchers compared stone points, believed to be spearheads, made of silcrete -- quartz grains cemented by silica -- from Blombos Cave, and compared them to points that they made themselves by heating and pressure-flaking silcrete collected at the same site.
The similarities between the ancient points and modern replicas led the scientists to conclude that many of the artifacts from Blombos Cave were made by pressure flaking, which scientists previously thought dated from the Upper Paleolithic Solutrean culture in France and Spain, roughly 20,000 years ago.
"This finding is important because it shows that modern humans in South Africa had a sophisticated repertoire of tool-making techniques at a very early time," said Villa.
The authors speculated that pressure flaking may have been invented in Africa and only later adopted in Europe, Australia and North America.
The new findings were published in the journal Science.