Early evidence found of sophisticated human tools
Early humans developed sophisticated techniques for sharpening stone spear points more than 75,000 years ago, at least 50,000 years earlier than archaeologists had previously believed, researchers reported Thursday.
The spear points, found at the Blombos Cave in South Africa, were sharp enough to pierce the skin of prey with relative ease, representing a significant technological advantage over the relatively blunt points that had previously been used, said archaeologist Paola Villa of the University of Colorado Museum of Natural History, a co-author of the paper appearing in the journal Science.
Similar spear points have been widely found throughout North America and Europe, but the oldest ones previously found were from southern France and were only about 25,000 years old. Researchers had assumed that humans developed the technology after they migrated out of Africa, but the new findings indicate that they discovered it much earlier and took it when they left
The first crude tools were made by using stones to chip flakes away from flint to produce a sharpened edge. The next development was to use softer strikes with wood or bone hammers to produce a finer edge. The technology discovered at Blombos, called pressure flaking, involves first heating the stone, then applying pressure with the point of a bone tool to produce even narrower and sharper tips.
Villa and her colleagues studied 159 points of silcrete — quartz grains naturally cemented by silica — as well as 700 flakes and 179 pieces that had not been worked, all from a cave layer dating from 72,000 to 76,000 years ago. They concluded that at least half the finished points had been heated and retouched by pressure flaking.
The team then made its own spear points using silcrete chunks collected from outcrops about 20 miles from Blombos Cave, creating ones virtually identical to those produced by the ancient people. They demonstrated that the materials could not be pressure flaked if they were not heated first.
Pressure flaking defined the period “as a time when novel ideas were rapidly introduced,” they wrote. “This flexible approach to technology may have conferred an advantage to the groups of Homo sapiens who migrated out of Africa about 60,000 years ago.”
