An experiment is casting doubt on the history of stone tools

It's one of the biggest controversies in archaeology.
Grant Currin
Olduvai stone chopping tool, made from basalt, from Olduvai Gorge, Tanzania, 1.8-2 million years old. British Museum (1934,1214.1).BabelStone / Wikimedia

Electronics, airplanes, internal combustion engines, and the wheel are the descendants of a far more rudimentary technology: stone tools. Early stone tools might seem simple, but their invention represents a massive milestone in the history of our species. 

Archaeologists have long believed the knowledge of how to make stone tools — what kind of materials to use, where to find them, and how to reshape rocks to make something useful — was the collective effort of many individuals working together and learning from each other. A new set of experiments where volunteers were brought into the lab to make stone tools suggests that may not be the case. The results were published Wednesday in the peer-reviewed journal Science Advances.

Archaeologist William Snyder, one of the co-authors, tells IE "we have shifted the timeline of the beginnings of cognitive humanness forward in time by hundreds of thousands, if not even one million years."

However, not everyone is convinced.

Archaeological experiments yield surprising results

The researchers brought 28 participants into the lab. Each one was given the raw materials they needed to accomplish a simple task: cutting a string to access a reward. Working by themselves, the participants had to figure out how to use the materials to make a tool capable of cutting the string. Here's the catch: they didn't get any instructions on how to do it. The researchers wanted to see if these regular people could figure out how to make the kind of tools ancient hominins were making two million years ago. 

The results of the experiment were stunning. During the four hours they had to work, all 28 of the research participants (including the two participants who'd never even heard of stone tools before) independently discovered toolmaking techniques that were used by the earliest toolmakers.

"The toolmaking techniques these individuals used were very much the same as the ones that would have been used over 2 million years ago. For now, we see this as strong proof of principle that one can re-innovate the techniques without having seen them," Snyder says.

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The results of the experiments aren't clear-cut

Archaeologist Justin Pargeter, who also researches early toolmaking but wasn't involved in these experiments, says he's glad the researchers behind the new study are bringing fresh data to a longstanding debate — but he's not convinced by the study's conclusions.

"If I look at these results, I see a set of technologies that have been replicated by these individuals that do not match with what we find [in the archaeological record from] 2.6 million years ago," he says. While the participants in the new study did discover the four major techniques ancient toolmakers employed, the modern-day toolmakers didn't show any preference for the technique most commonly used more than two million years ago, during the period the researchers are interested in.

As the number of artifacts in the archaeological record has grown, archaeologists are increasingly turning to the number of various types of tools to understand ancient technology. "The archaeological record is about numbers and frequencies. It's not about rare events," Pargeter says. That's important here because the study participants didn't develop techniques in ratios that match what's found in the period of interest for the study authors.  "The majority of behavior that pops up in this experiment is actually much more like [a] 3.3 million-year-old period," he says. Unfortunately, researchers don't know much about that earlier period because it's represented by a single site: Lomekwi, in northern Kenya.

"I think a lot of people would be quite happy to argue that, yeah, there's probably a lot of individual experimentation going on over 3 million years ago with hominins who are even further removed from our lineage," he says. 

The study authors disagree, writing "[a]bsent new lines of evidence, the earliest unequivocal evidence for technique transmission, and with it, cumulative culture of know-how, should be pushed forward to a later time." They call for more experiments to determine how recently cultural transmission of knowledge began.

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