The evolutionary stories of the Swiss Army Knife and the Big Mac just got a lot longer. An international team of scientists led by Dr. Zeresenay Alemseged from the California Academy of Sciences has discovered evidence that human ancestors were using stone tools and consuming meat from large mammals nearly a million years earlier than previously documented.
While working in the Afar Region of Ethiopia, Alemseged's "Dikika Research Project" team found fossilized bones bearing unambiguous evidence of stone tool use—cut marks inflicted while carving meat off the bone and percussion marks created while breaking the bones open to extract marrow. The bones date to roughly 3.4 million years ago and provide the first evidence that Lucy's species, Australopithecus afarensis, used stone tools and consumed meat. The research is reported in the August 12 issue of the journal Nature.
These two bones from Dikika, which have been dated to roughly 3.4 million years ago, provide the oldest known evidence of stone tool use among human ancestors. Both of the cut-marked bones came from mammals -- one is a rib fragment from a cow-sized mammal, and the other is a femur shaft fragment from a goat-sized mammal. Both bones are marred by cut, scrape, and percussion marks.
Credit: Dikika Research Project, California Academy of Sciences
"This discovery dramatically shifts the known timeframe of a game-changing behavior for our ancestors," says Alemseged, Curator of Anthropology at the California Academy of Sciences. "Tool use fundamentally altered the way our early ancestors interacted with nature, allowing them to eat new types of food and exploit new territories. It also led to tool making—a critical step in our evolutionary path that eventually enabled such advanced technologies as airplanes, MRI machines, and iPhones."
Although the butchered bones may not look like particularly noteworthy fossils to the lay person, Alemseged can hardly contain his excitement when he describes them. "This find will definitely force us to revise our text books on human evolution, since it pushes the evidence for tool use and meat eating in our family back by nearly a million years," he explains. "These developments had a huge impact on the story of humanity."
Dr. Zeresenay Alemseged, Curator of Anthropology at the California Academy of Sciences, excavates an ancient rhino skull at Dikika, Ethiopia. Alemseged's excavations at Dikika recently unearthed the oldest known evidence of stone tool use among human ancestors.
Credit: Dikika Research Project, California Academy of Sciences
Until now, the oldest known evidence of butchering with stone tools came from Bouri, Ethiopia, where several cut-marked bones were dated to about 2.5 million years ago. The oldest known stone tools, dated to around the same time, were found at nearby Gona, Ethiopia. Although no hominin fossils were found in direct association with the Gona tools or the Bouri bones, an upper jaw from an early Homo species dated to about 2.4 million years ago was found at nearby Hadar, and most paleoanthropologists believe the tools were made and used only by members of the genus Homo.
The new stone-tool-marked fossil animal bones from Dikika have been dated to approximately 3.4 million years ago and were found just 200 meters away from the site where Alemseged's team discovered "Selam" in 2000. Dubbed "Lucy's Daughter" by the international press, Selam was a young Australopithecus afarensis girl who lived about 3.3 million years ago and represents the most complete skeleton of a human ancestor discovered to date.
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