Unearthing of Stone Tools and Animal Bones in Kenya Offers Window Into the Dawn of Stone Technology
New research by a team of scientists reveals that early human relatives used some of the oldest stone tools ever found to both butcher hippos and to pound plant material. The work presents what are likely to be the oldest examples of a vital stone-age innovation known as the Oldowan toolkit, as well as the oldest evidence of hominins consuming very large animals.
The tools were used along the shores of Africa’s Lake Victoria in Kenya roughly 2.9 million years ago.
Excavations at the site, named Nyayanga and located on the Homa Peninsula in western Kenya, also produced a pair of large molars belonging to the human species’ evolutionary relative Paranthropus.
The study, which appears in the journal Science and was led by researchers at the Smithsonian’s Museum of Natural History and the City University of New York’s Queens College, included NYU biological anthropologist Shara Bailey, whose analysis of the newly discovered molars aided in identifying the species to which the teeth belonged—they turned out to belong to the oldest Paranthropus remains yet found.
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 scientists note, 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 the discovery reported in Science shows that these stone tools were used by early human ancestors to process a wide range of materials and foods, including plants, meat, and 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.
“It’s exciting to start closing the gap between the earliest stone tools, which are not associated with a hominin species, and later tools associated with our genus Homo,” says Bailey, director of NYU’s Center for the Study of Human Origins. “The fact that these tools are associated with Paranthropus may force us to rethink the capabilities of these enigmatic hominins.”
The presence of the teeth at a site where stone tools were also discovered raises questions about which human ancestor made those tools, adds 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 says. “But finding Paranthropus alongside these stone tools opens up a fascinating whodunnit.”
Though multiple lines of evidence suggest the artifacts are likely to be about 2.9 million years old, they can be more conservatively dated to between 2.6 and 3 million years old, says lead study author Thomas Plummer of Queens College, research associate in the scientific team of the Smithsonian’s Human Origins Program.
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 observes. “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.”
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.