Archaeologists Put Stone Tools Through Modern Engineering Tests
Phoenix666 writes:
Archaeologists working decades ago at Olduvai noticed that those now-extinct hominins had preferred particular kinds of stone for particular types of tools. For example, quartzite was a favorite for making the small, sharp-edged cutting tools called flakes, while basalt and other lavas seem to turn up more often in the form of large cutting tools like hand-axes. To figure out why, University of Kent anthropologist Alastair Key and his colleagues put Pleistocene-style stone tools through a battery of tests usually used in modern engineering research.
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.
Journal Reference:
Alastair Key, Tomos Proffitt, and Ignacio de la Torre. Raw material optimization and stone tool engineering in the Early Stone Age of Olduvai Gorge (Tanzania)$, The Royal Society https://royalsocietypublishing.org/doi/10.1098/rsif.2019.0377
It remains unconfirmed if the Olduvai engineers gamed the testing regimen...
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