Stone tools unearthed in Kenya reveal that hominins regularly moved raw materials several miles

In southwestern Kenya more than 2.6 million years ago, ancient humans wielded an array of stone tools—known collectively as the Oldowan toolkit—to pound plant material and carve up large prey such as hippopotamuses.

These durable and versatile tools were crafted from special stone materials collected up to eight miles away, according to new research led by scientists at the Smithsonian’s National Museum of Natural History, Cleveland Museum of Natural History and Queens College. Their findings, published Aug. 15 in the journal Science Advances, push back the earliest known evidence of ancient humans transporting resources over long distances by some 600,000 years.

“People often focus on the tools themselves, but the real innovation of the Oldowan may actually be the transport of resources from one place to another,” said Rick Potts, the senior author of the study and the National Museum of Natural History’s Peter Buck Chair of Human Origins. “The knowledge and intent to bring stone material to rich food sources was apparently an integral part of toolmaking behavior at the outset of the Oldowan.”

In the new Scientific Advances study led by Emma Finestone, the Robert J. and Linnet E. Fritz Endowed Chair of Human Origins at the Cleveland Museum of Natural History, Finestone and Potts worked with several colleagues to analyze stone tools uncovered on Kenya’s Homa Peninsula, a fossil-rich region that juts out into the eastern margins of Lake Victoria. Potts first surveyed the region’s fossil sites in 1985. In the years since, he has worked closely with colleagues at the National Museums of Kenya to excavate the area’s gullies as part of the ongoing Homa Peninsula Paleoanthropology Project, which Potts co-directs with Queens College professor Thomas Plummer, another co-author of the new paper. Finestone joined the project in 2012, when she began working with Plummer to reconstruct hominin tool behavior on the Homa Peninsula and understand how toolmakers moved around the landscape.

One of the peninsula’s most significant sites is known as Nyayanga and contains archaeological finds dating back some three million years. A series of recent excavations yielded a trove of stone tools and hundreds of butchered hippopotamus bones. In a 2023 paper, Plummer, Potts, Finestone and their colleagues posited that these bones represent the oldest known evidence of ancient hominins using stone tools to butcher large animals.

“Hominins were using stone tools for a variety of pounding and cutting tasks, including processing plant and animal foods and working wood,” Plummer said. “The diversity of activities that used stone tools suggests that even at this early stage of cultural development stone tools enhanced the adaptability of the hominins using them.”

The development of the Oldowan toolkit made it possible for early humans to consume large prey. Around three million years ago, ancient hominins began refining their toolmaking, using hammerstones to strike stone cores and create sharp-edged flakes. By pounding, slicing and scraping, these stone tools could process and refine a greater variety of plant and animal materials.

Finding the right rocks was vital. Oldowan tools needed to be fashioned from stones that were strong yet brittle enough to easily flake. However, the local rocks at Nyayanga are relatively soft, and would produce cutting tools that would quickly dull and pounding tools that would be more likely to shatter. Like using a flimsy plastic knife trying to cut through a well-done steak, these stones would have been of little use for pounding tough plants or breaking animal bones.

As a result, hominins at Nyayanga appear to have brought in stronger stones from other areas. The researchers analyzed the geochemistry of hundreds of stone cores and flakes found at Nyayanga that date back at least 2.6 million years. They discovered that these tools were crafted from volcanic rocks like rhyolite and metamorphic rocks like quartzite. The scientists surveyed local geology and discovered that these rock types were common in drainage basins several miles east of the Homa Peninsula.

According to Finestone, Nyayanga stones are significantly older than other known examples of ancient stone transport. Previously, the oldest evidence of hominins moving rocks over significant distances was a 2-million-year-old site known as Kanjera South that is also located on the Homa Peninsula.

“It’s surprising because the Nyayanga assemblage is early in the Oldowan and we previously thought that longer transport distances may have been related to changes that happened in our more recent evolutionary history,” she said.

The distance ancient hominins traveled for stones analyzed in this study is also noteworthy. While many nonhuman primates carry food and rocks, they only utilize materials that are nearby. Some, like chimpanzees, are known to transport stones over short distances. But the hominins at Nyayanga appear to have consistently procured material from over six miles away.

The ability to transport resources is a major milestone in human evolution. According to Potts, it exhibits ancient hominins’ ability to plan ahead and assess the requirements for processing food. It also illustrates an ability to mentally map their environment and remember locations with high-quality rocks.

“The mental maps of the oldest known hominins to persistently make stone tools well surpassed their immediate surroundings, even surpassing a few miles,” Potts said.

Once ancient hominins brought their lithic haul back to Nyayanga, they fashioned the stones into flakes and cores. But the identity of these toolmakers remains elusive. At the oldest hippo butchery site, the team discovered a molar tooth from a hominin in the genus Paranthropus, a group that sported strong skulls and teeth to grind tough material. Another Paranthropus tooth was found nearby on the surface of the same geological bed. The existence of Paranthropus teeth alongside Oldowan stone tools hints that these hominins may have used stone tools like their close evolutionary relatives in the genus Homo.

However, the case is far from closed.

“Unless you find a hominin fossil actually holding a tool, you won’t be able to say definitively which species are making which stone tool assemblages,” Finestone said. “But I think that the research at Nyayanga suggests that there is a greater diversity of hominins making early stone tools than previously thought.”

The artifacts at Nyayanga also underscore that ancient humans have transported raw materials to fuel technological innovations for millions of years.

“Humans have always relied on tools to solve adaptive challenges,” Finestone said. “By understanding how this relationship began, we can better see our connection to it today—especially as we face new challenges in a world shaped by technology.”

In addition to Potts, the new paper includes contributions from Rahab Kinyanjui and Michael Petraglia, who also are affiliated with the Smithsonian’s Human Origins Program. The study includes authors affiliated with the CUNY Graduate Center; New York Consortium in Evolutionary Primatology; University of Oxford; Max Planck Institute for Evolutionary Anthropology; George Washington University; University of Nairobi; Institute of Nuclear Chemistry and Technology; University of Nottingham Ningbo China; Illinois State Museum; National Museums of Kenya; Australian Research Centre for Human Evolution, Griffith University; University of Queensland; King’s College London; Sapienza University of Rome; and the Zinman Institute of Archaeology, Haifa University.

This research was supported by a collaborative agreement with the National Museums of Kenya and the Government of Kenya and by funding from the Smithsonian, Cleveland Museum of Natural History, the National Science Foundation, the Leakey Foundation, the Leverhulme Trust, the Donner Foundation, Robert J. and Linnet E. Fritz and the Peter Buck Fund for Human Origins Research.

Bibliographic information:

Press release from the Smithsonian.

L'articolo To craft Oldowan tools, hominins at Nyayanga transported stones over long distances 600,000 years earlier than previously thought proviene da Classicult.

Discovery of stone tools and cut-marked animal bones in Kenya offers window into the dawn of stone technology.

Along the shores of Africa’s Lake Victoria in Kenya roughly 2.9 million years ago, early human ancestors used some of the oldest stone tools ever found to butcher hippos and pound plant material, according to new research led by scientists with the Smithsonian’s National Museum of Natural History and Queens College, CUNY, as well as the National Museums of Kenya,  Liverpool John Moores University and the Cleveland Museum of Natural History.

The study, published today, Feb. 9, in the journal Science, presents what are likely to be the oldest examples of a hugely important stone-age innovation known to scientists as the Oldowan toolkit, as well as the oldest evidence of hominins consuming very large animals. Though multiple lines of evidence suggest the artifacts are likely to be about 2.9 million years old, the artifacts can be more conservatively dated to between 2.6 and 3 million years old, said lead study author Thomas Plummer of Queens College, research associate in the scientific team of the Smithsonian’s Human Origins Program.

Excavations at the site, named Nyayanga and located on the Homa Peninsula in western Kenya, also produced a pair of massive molars belonging to the human species’ close evolutionary relative Paranthropus. The teeth are the oldest fossilized Paranthropus remains yet found, and their presence at a site loaded with stone tools raises intriguing questions about which human ancestor made those tools, said Rick Potts, senior author of the study and the National Museum of Natural History’s Peter Buck Chair of Human Origins.

“The assumption among researchers has long been that only the genus Homo, to which humans belong, was capable of making stone tools,” Potts said. “But finding Paranthropus alongside these stone tools opens up a fascinating whodunnit.”

Whichever hominin lineage was responsible for the tools, they were found more than 800 miles from the previously known oldest examples of Oldowan stone tools—2.6-million-year-old tools unearthed in Ledi-Geraru, Ethiopia. This greatly expands the area associated with Oldowan technology’s earliest origins. Further, the stone tools from the site in Ethiopia could not be tied to any particular function or use, leading to speculation about what the Oldowan toolkit’s earliest uses might have been.

Through analysis of the wear patterns on the stone tools and animal bones discovered at Nyayanga, Kenya, the team behind this latest discovery shows that these stone tools were used by early human ancestors to process a wide range of materials and foods, including plants, meat and even bone marrow.

The Oldowan toolkit includes three types of stone tools: hammerstones, cores and flakes. Hammerstones can be used for hitting other rocks to create tools or for pounding other materials. Cores typically have an angular or oval shape, and when struck at an angle with a hammerstone, the core splits off a piece, or flake, that can be used as a cutting or scraping edge or further refined using a hammerstone.

“With these tools you can crush better than an elephant’s molar can and cut better than a lion’s canine can,” Potts said. “Oldowan technology was like suddenly evolving a brand-new set of teeth outside your body, and it opened up a new variety of foods on the African savannah to our ancestors.”

Potts and Plummer were first drawn to the Homa Peninsula in Kenya by reports of large numbers of fossilized baboon-like monkeys named Theropithecus oswaldi, which are often found alongside evidence of human ancestors. After many visits to the peninsula, a local man named Peter Onyango working with the team suggested they check out fossils and stone tools eroding from a nearby site that was ultimately named Nyayanga after an adjacent beach.

Beginning in 2015, a series of excavations at Nyayanga returned a trove of 330 artifacts, 1,776 animal bones and the two hominin molars identified as belonging to Paranthropus. The artifacts, Plummer said, were clearly part of the stone-age technological breakthrough that was the Oldowan toolkit.

Compared to the only other stone tools known to have preceded them—a set of 3.3-million-year-old artifacts unearthed at a site called Lomekwi 3, just west of Lake Turkana in Kenya—Oldowan tools were a significant upgrade in sophistication. Oldowan tools were systematically produced and often fashioned using what is known as “freehand percussion,” meaning the core was held in one hand and then struck with a hammerstone being wielded by the opposing hand at just the right angle to produce a flake—a technique that requires significant dexterity and skill.

By contrast, most of the artifacts from Lomekwi 3 were created by using large stationary rocks as anvils, with the toolmaker either banging a core against the flat anvil stone to create flakes or by setting the core down on the anvil and striking it with a hammerstone. These more rudimentary modes of fabrication resulted in larger, cruder and more haphazard-looking tools.

Over time, the Oldowan toolkit spread all the way across Africa and even as far as modern-day Georgia and China, and it was not meaningfully replaced or amended until some 1.7 million years ago when the hand-axes of the Acheulean first appeared.

As part of their study, the researchers conducted microscopic analysis of wear patterns on the stone tools to determine how they were used, and they examined any bones seen to exhibit potential cut marks or other kinds of damage that might have come from stone tools.

The site featured at least three individual hippos. Two of these incomplete skeletons included bones that showed signs of butchery. The team found a deep cut mark on one hippo’s rib fragment and a series of four short, parallel cuts on the shin bone of another. Plummer said they also found antelope bones that showed evidence of hominins slicing away flesh with stone flakes or of having been crushed by hammerstones to extract marrow.

The analysis of wear patterns on 30 of the stone tools found at the site showed that they had been used to cut, scrape and pound both animals and plants. Because fire would not be harnessed by hominins for another 2 million years or so, these stone toolmakers would have eaten everything raw, perhaps pounding the meat into something like a hippo tartare to make it easier to chew.

Using a combination of dating techniques, including the rate of decay of radioactive elements, reversals of Earth’s magnetic field and the presence of certain fossil animals whose timing in the fossil record is well established, the research team was able to date the items recovered from Nyayanga to between 2.58 and 3 million years old.

“This is one of the oldest if not the oldest example of Oldowan technology,” Plummer said. “This shows the toolkit was more widely distributed at an earlier date than people realized, and that it was used to process a wide variety of plant and animal tissues. We don’t know for sure what the adaptive significance was but the variety of uses suggests it was important to these hominins.”

The discovery of teeth from the muscular-jawed Paranthropus alongside these stone tools begs the question of whether it might have been that lineage rather than the Homo genus that was the architect of the earliest Oldowan stone tools, or perhaps even that multiple lineages were making these tools at roughly the same time.

The excavations behind this study offer a snapshot of the world humans’ ancestors inhabited and help illustrate the ways that stone technology allowed these early hominins to adapt to different environments and, ultimately, give rise to the human species.

“East Africa wasn’t a stable cradle for our species’ ancestors,” Potts said. “It was more of a boiling cauldron of environmental change, with downpours and droughts and a diverse, ever-changing menu of foods. Oldowan stone tools could have cut and pounded through it all and helped early toolmakers adapt to new places and new opportunities, whether it’s a dead hippo or a starchy root.”

This research was supported by funding from the Smithsonian, the Leakey Foundation, the National Science Foundation, the Wenner-Gren Foundation, the City University of New York, the Donner Foundation and the Peter Buck Fund for Human Origins Research.

Bibliographic information:

Expanded geographic distribution and dietary strategies of the earliest Oldowan hominins and Paranthropus, Science (9-Feb-2023), DOI: 10.1126/science.abo7452

Press release from Smithsonian.

L'articolo 2.9-million-year-old butchery site, Nyayanga, reopens case of who made first stone tools proviene da Classicult.