From nature to knapping: The surprising origins of stone tools

The invention of sharp stone tools – known as “knapping” – marked a turning point in early human evolution, allowing our ancestors to access new food resources, from tough plant fibers to animal carcasses. 

This technological leap played a critical role in the expansion of brain size and the complex development of human society. 

But what led to this moment? How did the very first humans begin making sharp-edged tools in the first place?

Earliest origins of stone tools

A team of 24 scientists, led by researchers at the Cleveland Museum of Natural History, has proposed a new hypothesis to explain the earliest origins of stone tool production. 

Their theory suggests that before hominins intentionally chipped stone to make tools, they likely used sharp rocks already shaped by natural forces. 

The study was co-authored by Dr. Emma Finestone, an associate curator at the museum, along with Dr. Michelle R. Bebber and Dr. Metin I. Eren, research associates at the museum and professors at Kent State University.

Nature’s knives came first

“I don’t think it was a ‘Eureka!’ moment whereby hominins first made a sharp stone flake by intention or by accident and then went to look for something to cut,” explained Dr. Eren. “There is no reason to produce sharp stone tools unless the need to cut is already in place.”

Instead, the team argues that early humans began by using what they call “naturaliths” – naturally occurring sharp rocks that formed through geological processes like river erosion or animal trampling. While previous research had suggested these natural cutting tools were rare, the new study challenges that view.

Drawing from global fieldwork and a comprehensive review of scientific literature, the researchers show that these naturally formed sharp rocks are surprisingly common. In fact, the production of naturaliths appears to happen continuously in many environments around the world, often in large quantities.

“In some cases, sharp rocks are produced by Mother Nature in the hundreds, thousands, or more,” said Dr. Bebber, who encountered one such site during her work in Oman. “It is quite astonishing…natural knives were likely readily available to our hominin ancestors.”

Exploiting nature’s stone tools

Finestone’s own research in Kenya reveals that early human activity sites often appear near places where stone is naturally abundant. 

“A hominin could have picked up and used a naturally sharp rock to process a carcass or plant material that might have been difficult to access using just their hands and teeth,” she said.

This suggests that early hominins likely began by exploiting natural tools already present in their environment. Only after becoming accustomed to using sharp edges would there have been evolutionary pressure to begin making their own – especially in places where naturaliths were scarce or where finer control over tool shape and sharpness was needed.

In other words, once early humans recognized the usefulness of sharp edges, the challenge became one of supply and customization. 

Knapping may have emerged not as a sudden invention, but as a gradual response to practical needs: how to create sharp rocks on demand, in any location, and with particular features suited to specific tasks.

The roots of technology

“This is the most parsimonious hypothesis for the origin of hominin stone technology to date,” said Dr. Eren. “But parsimony is not necessarily correct – archaeologists now need to test our hypothesis and search for naturalith use by hominins between 3 and 6 million years ago.” 

“It is an exciting prospect… if hominins are using naturally sharp rocks as knives, then the archaeological record is going to get a whole lot older.”

If confirmed, the idea could push back the timeline of human technological behavior by hundreds of thousands – or even millions – of years. 

Tools made intentionally through knapping have been dated to at least 3.3 million years ago. But if hominins were using naturally sharp stones before they ever struck two rocks together, the behavioral roots of technology may lie deeper in prehistory than previously assumed.

The evolution of stone tools

The new hypothesis offers a refreshing shift in how we think about the dawn of toolmaking. Rather than a single “light bulb” moment, the origins of stone technology may reflect a gradual process shaped by the resources early humans found in their surroundings. 

Recognizing the value of sharp edges likely preceded the skill of making them, and innovation may have begun not with invention, but with observation and adaptation.

As researchers begin searching the archaeological record for evidence of early naturalith use, this theory opens new possibilities for understanding how hominins evolved to shape the world around them – starting with the simple, sharp gift of nature itself.

The study is published in the journal Archaeometry.

Image Credit: Archaeometry (2025)

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