On the Homa Peninsula in southwestern Kenya, east of Lake Victoria, lies an archaeological site where researchers have found some of humanity’s oldest tools. These implements, known to experts as Oldowan—named after the Olduvai Gorge, an archaeologically rich site nearby in Tanzania—were shaped by our human ancestors into an impressive variety of wedges and hammers between 2.6 million and 1.6 million years ago, at the very start of the Stone Age. Studying this breakthrough technology, researchers have gained new insights into this Lower Paleolithic phase of human evolution. Long before widespread agriculture, the development of Oldowan led to better-fed, smarter hominins—and may well have enabled these largely itinerant early humans to begin establishing a sense of home.
The site, known as Kanjera South, was established in 1987 by the National Museums of Kenya in collaboration with the Smithsonian’s Human Origins Program, whose founding director, the paleoanthropologist Richard Potts, began excavations that summer. Kenyans worked alongside U.S.-educated archaeologists, including Thomas Plummer, then a doctoral student at Yale University, whom Potts had met while teaching there.
According to Potts, it was Plummer who suggested the group would find far greater archaeological riches if they focused their attention around 800 feet to the south. And, sure enough, Potts and Plummer soon unearthed a mesmerizing stone tool approximately two million years old. On loan from the Kenyan government since 2011, this stone, known as the Kanjera tool after the site where it lay buried, is the oldest human-made object in any Smithsonian collection.
The stone appears well used, the scars on its numerous edges indicating serious wear and tear. The business sides of the tool are marked by flakes, the result of a chipping process that created serrated edges sharp enough for cutting. The handle side, meanwhile, is flat and smooth. It’s easy to imagine this rock as it was before hominins instrumentalized it—a flat, rounded stone.
While visitors to the Smithsonian will not get a chance to hold the tool, anyone can see it fits nicely in one’s hands; according to Potts, the implement offers an easy grip and weighs about half a pound. Also notable is the reddish iron color on the 12 flakes of the sharp end. Though such a color typically points to a volcanic origin, and though hominins often used volcanic rocks for tools, geological analysis indicates that the Kanjera stone is actually a quartzite rock, and non-volcanic. Smithsonian archaeologists surmise it may have been pulled from the ground five or six miles away from Kanjera South. Most likely, then, hominins struck and used the Kanjera tool at various other locations before it found its final resting place.
To make a sharp tool such as the Kanjera stone, a hominin would use a hammer stone to serrate the new tool, creating sharp edges capable of cutting different materials, from animal flesh to vegetation to wood. The consequence of our ancestors’ innovating the sharper tools of the Oldowan is that all sorts of food in the African savanna, from the grasslands to the wetlands, became newly available: Hominins could suddenly cut and prepare tubers, which entered their diet in this period, and meat became more regular fare, as hominins scavenged antelopes and other prey from larger predators, such as lions. Researchers at Kanjera South have discovered a variety of animal bones dating to the same period scarred by stone tools—some of the earliest evidence of human carnivory.
Potts says these novel Oldowan helped hominins adjust to an impressive array of environments, now that their diet included “everything that any animal could eat in African environments, in a very, very dynamic world of environmental change.” Some researchers even suggest that this new diet contributed to an increase in human brain size.
Yet perhaps equally important, the Kanjera stone evokes a period of transition from an itinerant life to one more rooted in a particular place. The first generations to pioneer these tools treated Kanjera South as their headquarters. Further excavation has revealed that these early humans made “repeated visits to [Kanjera South] over hundreds to thousands of years,” Briana Pobiner, a paleoanthropologist with the Smithsonian Human Origins Program, once wrote. Collecting quartzite rocks on their forays into surrounding areas, these ancestors returned to Kanjera South over and over to make more tools, to gather, to eat, to live. “There is this hint that this place is the beginning of a sense of home for early humans,” Potts says.