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Wednesday, November 17, 2010

Stone tool advancements

Left: Oldowan stone tool; Right: Acheulean stone tool

Starting about 2.5 million years ago, early hominids developed the technology to shape simple stone knives. After that, there was no advancement for almost two million years. Then, about 500,000 years ago, the hand axe was developed. Why did it take so long to achieve this technological breakthrough? According to new research lead by Aldo Faisal of Imperial College, London, humans had to wait for their brains to catch up with their hands.

There had been a couple of prevailing theories as to why there was such a long lag time between the development of the first stone tools and the creation of more sophisticated axes and knives. One view was that early hominids lacked the manual dexterity and precision required to fashion the more delicate items. The other view was that we simply didn’t have the computing power needed to visualize and plan complex tool-making.

Faisal and his team outfitted an experienced flint-knapper (someone proficient at making stone tools) with a specialized ‘cyberglove’ that recorded data on grip and movement. The flint-knapper created both simple (Oldowan) stone tools and more complex (Acheulean) tools. He also performed a variety of manual activities that involved sorting and gripping items. The researchers found that the manual dexterity required to make both simple and complex tools was the same. In other words, the limiting factor in early tool use was not physical, but cognitive. Perhaps not coincidentally, the mental leap to the manufacture of complex tools coincided with the development of language.

By the way, it's not clear exactly which hominid species was responsible for inventing these different tools. Oldowan tools have been associated with some Australopithecines, and also with some early Homo species. Acheulean tools have been found with the remains of Homo erectus.

You can watch Dietrich Stout, an Emory archeologist and one of the authors on the study, discuss the making of stone tools below.