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Phoenix666 [soylentnews.org] writes:

Ars Technica [arstechnica.com]:

Key and his colleagues wanted to know whether H. habilis and H. erectus knew how to choose the most practical materials for specific tools or jobs. To find out, the archaeologists compared the sharpness and durability of Olduvai basalt, chert, and quartzite: three of the most common materials for stone tools in and around the gorge. And that required letting a robot play with some replica stone tools.

An engineering testing machine lowered each sharp stone flake onto a 2mm-wide section of PVC pipe and recorded how much force had to apply to cut through the pipe, and how much the pipe’s surface gave way before splitting. To test durability, Key and his colleagues put the machine to work cutting through oak branches with the replica flakes, then measured how well each blade held its edge between uses.

Quartzite turned out to be the sharpest stone on the list, with chert coming in a close second. Basalt’s sharpness wasn’t terribly impressive; if you want to cut something with a basalt flake, it’s going to take about twice as much energy as using a chert or quartzite flake. So it makes sense that hominins at Olduvai Gorge would pick quartzite or chert for small flakes—quickly made cutting tools that would have been tossed aside after use (they're the plastic sporks of the Pleistocene).

A brand-new basalt biface is a bit duller than a biface made of chert or quartzite, but the basalt tool will hold its edge much better over time. And it seems that H. habilis tool-makers knew that 1.8 million years ago, because dull but sturdy basalt was a more common choice for heavier work or for larger cutting tools, which would be used over and over. Key and his colleagues suggest that’s not a coincidence.

It remains unconfirmed if the Olduvai engineers gamed the testing regimen...

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