Our Ancient Ancestors Were Pretty Excellent Engineers
Scientists used robots and replica tools to stress test ancient materials and designs used by hominins.
Humans aren't millions of years old, but toolmaking certainly is.
Ancient hominins chose materials based on what worked best for the work they were doing.
Archaeologists are testing ancient stone tool designs using very modern engineering. In the journal Royal Society Interface, a group of three archaeologists based in England and Spain surveyed tools found at the two-million-year-old Olduvai Gorge site and ran them through engineering tests to try and understand if ancient hominins were iterating better and better materials and designs.
The archaeologists noticed that tools in different families were made with different materials, the same way a mallet is made of a different material than a saw or a socket wrench. Especially in a time before there was any kind of forging, ancient hominins could only use what they could find in pretty pure form in their local environments.
“For more than 1.8 million years hominins at Olduvai Gorge were faced with a choice: whether to use lavas, quartzite, or chert to produce stone tools,” the researchers explain. Lavas include igneous rocks like basalt and granite. Chert is a subgroup of sedimentary rock and includes flint, opal, and jasper.
If toolmaking was more of an unstudied crapshoot, scientists would expect tools of all kinds to be made with all three of these families of stone. Instead, the sharpest, finest cutting tools were made of delicate, but fine-textured quartzite. Bulkier, more heavy-duty cutting tools were made from lavas. The archaeologists saw a clear pattern in toolmaking, but was that evidence-based? Were ancient hominins using kind of a scientific method?
To find out, the research team made a bunch of replica tools and found a robot to stress test them. They tested sharp cutting on lengths of PVC pipe and longer-term durable cutting on tree branches. “We quantify the force, work and material deformation required by each stone type when cutting, before using these data to compare edge sharpness and durability,” the scientists write.
A sharp, fine cutting tool could be used for a ton of different jobs, from gathering wild food to scraping the bark off of sticks. Functionally it’s more like a knife, and while it certainly could be durable, that’s a lot less important than holding a sharp edge. Compare that with a larger cutting implement that’s usually used like an axe. An axe isn’t just sharp—it’s also a tough wedge that you must be able to bury in a log in order to keep forcing the two sides apart.
The edge still has to be sharp, but the axe itself must be very durable and strong. You wouldn’t use a knife to cut down a tree any more than you’d use a hand axe to cut down fine grasses or peel sticks—at least not if you had a choice. “When combined with artifact data, we demonstrate that Early Stone Age hominins optimized raw material choices based on functional performance characteristics,” the scientists write.
This shows that ancient hominins weren’t only making tools. They were considering what happened with past tools and making decisions based on what had worked best. That level of abstraction and logical decision-making is itself an accomplishment for a species that predated humans by more than a million years.
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