Archaeology | Human Origins
by Evan Hadingham
At first glance, they might look like broken garden rocks. But the sharp-edged river cobbles unearthed at Gona in Ethiopia—about five miles from Hadar, where Donald Johanson discovered Lucy—have been a focus of scientific investigation for over two decades. Stone tools for cutting and pounding enabled our ancestors to process meat and plants more efficiently, expanding their diet and releasing calories to fuel bigger brains. These tools were long considered a crucial innovation of our genus, Homo. But the groundbreaking finds at Gona, and subsequent discoveries (many funded by The Leakey Foundation), have overturned simple assumptions and inspired a quest to pin down the elusive identity of the first toolmakers.
“You needed to be a goat”
The Gona project was founded by Ethiopian-born Sileshi Semaw, a paleoanthropologist at Spain’s Centro Nacional de Investigación sobre la Evolución Humana (CENIEH). Raised in a disadvantaged neighborhood of Addis Ababa, Semaw overcame many challenges until a scholarship enabled him to pursue graduate studies at Rutgers University.
In 1992, he carried out the first systematic excavations at Gona in the harsh badlands of Ethiopia’s Awash Basin. When eventually published, two of these sites triggered global headlines: they consisted of thousands of undisturbed stone tools securely dated to around 2.6 million years ago—the earliest date for the world’s first stone tool technology, known as the Oldowan.
“That was extraordinary,” says Semaw, “because it was the first time that abundant materials dated to such antiquity were discovered in the world.”
In 2000, Semaw’s colleague and co-director of the Gona project, Michael Rogers of Southern Connecticut State University, made another momentous discovery. Rogers jokes, “You needed to be a goat,” recalling how he scrambled around Gona’s steep, crumbling gullies that fiercely hot February morning.
Hundreds of tools
At a spot later called OGS-7, Rogers glimpsed a scatter of sharp little stone flakes that looked unnatural. They were eroding from a 4-inch-thick layer of silt below a layer of volcanic ash, mixed with fragments of animal bone. When Rogers’ team dug down to expose the layer, they revealed hundreds more stone tools and bone fragments in near-perfect condition, lying undisturbed for more than 2.5 million years.
“We kept pinching ourselves,” he says. “It looked as if the tools were made yesterday.” Moreover, at other nearby sites, the animal bones mixed with the tools bore cut marks—telltale signs of butchering. They had found the world’s earliest stone tools definitively associated with processing animals.
Two opposing views of Oldowan (top) and Acheulian (bottom) stone tools from DAN5 at Gona. Photo Credit: Dr. Michael J. Rogers, Southern Connecticut State University
Selecting stones with skill
OGS-7 yielded many other intriguing clues. Whoever fashioned the tools had fetched cobbles from a streambed, then struck them together systematically to produce sharp-edged flakes capable of cutting open a carcass. After studying gravel from the ancient streambeds, the Gona researchers realized that the toolmakers had carefully selected rare, fine-grained volcanic cobbles, which were easier to work with and produced a sharper edge.
Not only had they picked out the best kind of stone for flaking, but modern experimenters have found it takes careful hand-eye coordination and many hours of practice to reproduce the skills apparent in the ancient debris. The toolmakers evidently held a river cobble in one hand while systematically and precisely striking sharp flakes off it with a hammerstone grasped in the other.
“If this was the earliest site in the world,” says Rogers about OGS-7, “we expected things to be crude, but the tools appear to have been well made.” That begged the question: just how much earlier did the very first, cruder efforts at toolmaking begin?
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A wrong turn in Kenya
On July 9, 2011, archaeologist Sonia Harmand of Stony Brook University was driving her jeep in a desolate area known as Lomekwi near the shores of Lake Turkana in Kenya when she took a wrong turn and ended up in a dead-end gully. Deciding to look around, she stumbled on a scatter of stone debris. Her team eventually recovered around 150 artifacts that are larger and less well-shaped than the Gona tools.
Some flakes are as big as a human hand while other worked rocks weigh up to 30 pounds—seemingly too unwieldy for butchering meat. Experiments suggest the Lomekwi tools were the product of a more primitive technique: instead of holding a cobble in one hand and carefully striking it with a hammerstone, the toolmakers used two methods. They either held a cobble in both hands and struck it against a larger rock or placed it on an anvil and smashed it with a hammerstone.
Today, chimpanzees in the Ivory Coast’s Taï forest and capuchin monkeys in Costa Rica use a similar hammering technique to crack open hard-shelled nuts.
Dated to 3.3 million years old, the Lomekwi tools raise major questions. Were they a one-off episode? A transition between using natural rocks and crafting sharp tools? And who was making them? Lomekwi is roughly contemporary with Lucy and predates the earliest known Homo, raising the possibility that australopithecines—whose brains were only slightly bigger than a chimpanzee’s—may have been the first toolmakers.
The hippo inquest
In 2023, the publication of a surprising discovery in Kenya pointed to another possible candidate. An international team led by Queens College anthropologist Tom Plummer investigated the site of Nyayanga, overlooking Lake Victoria. They excavated skeletons of two hippos and other animals, some bearing cut marks, mingled with characteristic Oldowan cores, pounding tools, and flakes.
Microscopic analysis of these tools indicates they were used for butchering animals, cutting plants, pounding tubers, and possibly woodworking. Dated to 2.6–2.9 million years ago, the Nyayanga finds are currently the world’s earliest systematically worked stone tools. They are potentially 300,000 years older than the Oldowan artifacts at Gona.
The real surprise came as Plummer’s team was excavating hippo bones under an approaching thunderstorm. Blasto Onyango, head fossil preparator at the National Museums of Kenya, found most of a lower hominin molar, directly associated with the butchered hippo skeleton. The tooth belonged neither to Homo nor Australopithecus, but to Paranthropus, a genus known for its massive jaws, robust build, and chimp-sized brain.
Plummer notes, “The fact that we found what’s probably the earliest Oldowan site and that the hominin found there is Paranthropus made us reconsider whether the traditional assumption of Homo as the first toolmaker should be made.”
The original “Nutcracker Man”
Ironically, back in 1959, the first sensational fossil human find in East Africa pointed to Paranthropus as a likely toolmaker. At Olduvai Gorge in Tanzania, Mary Leakey found a rugged skull near an array of stone tools—later named “Oldowan” by Louis Leakey.
At first, Louis Leakey identified the skull—nicknamed “Nutcracker Man”—as responsible for the tools. But less than a year later, remains of a less primitive-looking ancestor appeared at Olduvai. Leakey named the new find Homo habilis, or “handy man.” He dismissed Paranthropus as the innovator, arguing that only the human lineage could be responsible for such a breakthrough.
For decades, the Leakeys’ influence helped entrench the idea that only Homo made tools. Yet hand and wrist anatomy shows that australopithecines and Paranthropus were perfectly capable of the precision grip needed to make and use tools.
Moreover, further clues linking Paranthropus with stone tools emerge from South Africa. Oldowan technology appears in the limestone caves of The Cradle of Humankind, about an hour’s drive from Johannesburg. In those caves, two-million-year-old Paranthropus remains mingle with tools. Although early Homo remains are also found there, it now seems likely that more than one hominin species made tools.
A multitude of toolmakers
The investigations Semaw began at Gona in the 1990s marked the start of a broader reassessment of our ancient technological origins. If ancestors besides Homo were among the first toolmakers, wildlife studies remind us that many living species can make tools from stone and other materials—not only primates, but Caledonian crows, dolphins, octopuses, sea otters, and more.
As in so many areas of science, old assumptions about human uniqueness are giving way to a richer, humbler view. Our capacity to innovate is one of many traits we share with the endless variety of creatures on our planet.
This story by Evan Hadingham is based on an essay from the book Discovering Us: Fifty Great Discoveries in Human Origins. Find the book at your local bookstore and listen to the Discovering Us podcast with Ashley Judd
