Prehistoric people in southern Africa developed a highly skilled way of shaping stones into sharp-edged tools long before Europeans did, suggested a study released Thursday.
A technique known as pressure-flaking, which scientists previously thought was invented in Europe some 20,000 years ago, involves using an animal bone or some other object to exert pressure near the edge of a stone piece and precisely carve out a small flake.
Researchers from the University of Colorado at Boulder examined stone tools dating from the Middle Stone Age, some 75,000 years ago, from Blombos Cave in what is now South Africa.
The team found that 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.
The technique provides a better means of controlling the sharpness, thickness and overall shape of two-sided tools like spearheads and stone knives, said Paola Villa, a curator at the University of Colorado Museum of Natural History and a co-author of the study published in the journal Science.
"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 said. "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.