Researchers working in Ethiopia's remote Afar region have recovered evidence that humans began using stone tools and eating meat far earlier than previously thought. The finds—cut-marked animal bones dating to nearly 3.4 million years ago—push the origin of butchery back a stunning 800,000 years. Furthermore, these ancient butchers were not members of our own genus, Homo, but the more primitive Australopithecus, specifically A. afarensis, the species to which the celebrated Lucy fossil belongs.
Scientists have typically viewed tool use as the purview of Homo. Indeed, in 1964 Kenyan paleoanthropologist Louis Leakey and his colleagues named the earliest Homo species, H. habilis ("handy man"), for its association with stone tools. Subsequent finds have since extended the evidence of stone tool use back to between 2.5 million and 2.6 million years ago. But exactly which member of the human family made and wielded these older tools was unclear, both because no human remains turned up in direct association with the tools and animal bones, and more than one human species lived in the area at this time. The earliest example of a clear association between humans and tools dated to 2.3 million years ago, and the human remains belonged to an early Homo species.
Still, archaeologists suspected that earlier stone tools remained to be discovered, because these examples seemed too advanced to represent humanity's first foray into tool manufacture. "Nearly everyone that works with the earliest stone tool industries at between 2.3 [million] and 2.5 million years has commented on the surprisingly high level of skill and understanding that we see in these early knappers. Most have predicted that something older will be found," says archaeologist Shannon P. McPherron of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.
That hunch helped motivate McPherron and his colleagues, who have been working at a site in the Afar region called Dikika—just a few kilometers from the Lucy site—to look in older geologic deposits in the area for earlier evidence of stone tool use or manufacture. They were rewarded with bones from two animals—one cow-size and another goat-size—that display cutmarks and percussion marks indicative of flesh removal and marrow extraction with stone tools. McPherron, along with Dikika Research Project leader Zeresenay Alemseged of the California Academy of Sciences and their collaborators, describe their discovery in an August 12 paper in Nature (Scientific American is part of Nature Publishing Group).
Because the earliest Homo remains date to just 2.3 million years ago, scientists can be certain that an australopithecine made the cut marks on the 3.4-million-year-old Dikika bones. And because the only human species that is known to have lived in the Dikika area during this time period is A. afarensis, it seems reasonably certain that this species in particular butchered the bones. (The A. afarensis remains found at Dikika include a spectacularly well-preserved skeleton of a youngster, popularly dubbed "Lucy's baby.")
Australopithecines had teeth and jaws that were in many ways adapted for eating fruit, seeds and other plant foods. "[The discovery] shows that meat was added to the diet earlier than we had thought," McPherron observes, although he notes that it is difficult to say what portion of the diet was meat. "We could now be looking at an extended period of time when hominins were including meat in their diet and experimenting with the use of stone tools."
Although the Dikika finds prove that A. afarensis was using tools, whether they were fashioning implements from stone or just picking up sharp-edged rocks from the landscape and using those to carve up the carcasses remains unknown, because no stone tools have turned up at the site. Future discoveries may resolve this question. They may also reveal the extent to which Lucy and her kin relied on stone gadgetry, setting the stage for developments that would profoundly impact the course of human evolution.
"This discovery dramatically shifts the known time frame of a game-changing behavior for our ancestors," Alemseged remarked in a prepared statement. "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."