After a decade-long excavation at a remote site in Kenya, scientists have unearthed evidence that our early human relatives continuously fashioned the same tools across thousands of generations, hinting that sophisticated tool use may have originated much earlier than previously known, according to a new study in Nature Communications.
The discovery of nearly 1,300 artifacts—with ages that span 2.44 to 2.75 million years old—reveals that the influential Oldowan tool-making tradition existed across at least 300,000 years of turbulent environmental shifts. The wealth of new tools from Kenya’s Namorotukunan site suggest that their makers adapted to major environmental changes in part by passing technological knowledge down through the ages.
“The question was: did they generally just reinvent the [Oldowan tradition] over and over again? That made a lot of sense when you had a record that was kind of sporadic,” said David R. Braun, a professor of anthropology at the George Washington University who led the study, in a call with 404 Media.
“But the fact that we see so much similarity between 2.4 and 2.75 [million years ago] suggests that this is generally something that they do,” he continued. “Some of it may be passed down through social learning, like observation of others doing it. There’s some kind of tradition that continues on for this timeframe that would argue against this idea of just constantly reinventing the wheel.”
Oldowan tools, which date back at least 2.75 million years, are distinct from earlier traditions in part because hominins, the broader family to which humans belong, specifically sought out high-quality materials such as chert and quartz to craft sharp-edged cutting and digging tools. This advancement allowed them to butcher large animals, like hippos, and possibly dig for underground food sources.
When Braun and his colleagues began excavating at Namorotukunan in 2013, they found many artifacts made of chalcedony, a fine-grained rock that is typically associated with much later tool-making traditions. To the team’s surprise, the rocks were dated to periods as early as 2.75 million years ago, making them among the oldest artifacts in the Oldowan record.
“Even though Oldowan technology is really just hitting one rock against the other, there's good and bad ways of doing it,” Braun explained. “So even though it's pretty simple, what they seem to be figuring out is where to hit the rock, and which angles to select. They seem to be getting a grip on that—not as well as later in time—but they're definitely getting an understanding at this timeframe.”
The excavation was difficult as it takes several days just to reach the remote offroad site, while much of the work involved tiptoing along steep outcrops. Braun joked that their auto mechanic lined up all the vehicle shocks that had been broken during the drive each season, as a testament to the challenge.
But by the time the project finally concluded in 2022, the researchers had established that Oldowan tools were made at this site over the course of 300,000 years. During this span, the landscape of Namorotukunan shifted from lush humid forests to arid desert shrubland and back again. Despite these destabilizing shifts in their climate and biome, the hominins that made these tools endured in part because this technology opened up new food sources to them, such as the carcasses of large animals.
“The whole landscape really shifts,” Braun said. “But hominins are able to basically ameliorate those rapid changes in the amount of rainfall and the vegetation around by using tools to adapt to what’s happening.”
“That's a human superpower—it’s that ability we have to keep this information stored in our collective heads, so that when new challenges show up, there's somebody in our group that remembers how to deal with this particular adaptation,” he added.
It’s not clear exactly which species of hominin made the tools at Namorotukunan; it may have been early members of our own genus Homo, or other relatives, like Australopithecus afarensis, that later went extinct. Regardless, the discovery of such a long-lived and continuous assemblage may hint that the origins of these tools are much older than we currently know.
“I think that we're going to start to find tool use much earlier” perhaps “going back five, six, or seven million years,” Braun said. “That’s total speculation. I've got no evidence that that's the case. But judging from what primates do, I don't really understand why we wouldn't see it.”
To that end, the researchers plan to continue excavating these bygone landscapes to search for more artifacts and hominin remains that could shed light on the identity of these tool makers, probing the origins of these early technologies that eventually led to humanity’s dominance on the planet.
“It's possible that this tool use is so diverse and so different from our expectations that we have blinders on,” Braun concluded. “We have to open our search for what tool use looks like, and then we might start to see that they're actually doing a lot more of it than we thought they were.”