Archaeologists in northern Tanzania have found a set of bone tools dating back 1.5 million years, which are now universally recognized as the oldest known bone tools ever discovered, predating previous finds by an almost unimaginable one million years.
Stone tools linked to human ancestor species have been traced back at least 3.3 million years. But before this find, the oldest bone tools dated to between 250,000 and 500,000 years in the past. But 27 freshly examined bone fragments, primarily from ancient versions of hippopotamuses and elephants, exhibit unambiguous evidence of intentional shaping, likely through the application of stone tools. Some measure up to nearly 15 inches (38 centimeters) in length, making it clear they were being used for heavy-duty work.
These tools, systematically crafted in a uniform style, were discovered in Tanzania’s Olduvai Gorge, a renowned archaeological site known for yielding some of the earliest hominin artifacts. The findings, published in the journal Nature, suggest that early human relatives adapted stone-tool-making techniques to work with bone, demonstrating impressive cognitive skills such as pattern recognition and problem-solving.
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“This expansion of technological potential indicates advances in the cognitive abilities and mental structures of these hominins, who knew how to incorporate technical innovations by adapting their knowledge of stone work to the manipulation of bone remains,” said Dr. Ignacio de la Torre, the lead study author and a researcher affiliated with the Spanish National Research Council, in a statement quoted by CNN.
Set of tools made from elephant bones by human ancestors living in Olduvai Gorge, Tanzania 1.5 million years ago. (de la Torre, et.al/Nature).
Olduvai Gorge Opens Window into Human Evolution
Olduvai Gorge, located in East Africa, is a UNESCO World Heritage site known as the “Cradle of Humankind” due to its significant contributions to our understanding of early human evolution. The site has revealed evidence of tool production and use by early hominins, including Homo habilis, Homo erectus, and early Homo sapiens.
The archaeological record of Olduvai Gorge spans from two million to 20,000 years ago, capturing a long-erm progression of cultural and technological advancements. During the Oldowan period, beginning around 2.7 million years ago, ancient humans crafted simple tools by striking rocks to produce sharp flakes. The more complex Acheulean tools, such as hand axes, emerged approximately 1.7 million years ago, showcasing a clear and distinct evolution in craftsmanship.
It would seem the hominins responsible for this breakthrough eventually got the idea to expand their toolkit through the use of bone, through a leap of imagination that many researchers would have thought was impossible.
Shockingly Early Innovations in the Human Evolutionary Line
The excavations that led to the discovery of these bone tools took place between 2015 and 2022. Researchers initially focused on a particular gully in Olduvai Gorge, after discovering hominin teeth on the surface during fieldwork between 2010 and 2011.
The largest tools, measuring between 8.6 and 15 inches (22 to 38 centimeters) in length and up to 6 inches (15 centimeters) in width, came from elephant bones, while slightly smaller tools, ranging from 7 to 12 inches (18 to 30 centimeters), were crafted from hippo bones. These tools were shaped using knapping techniques previously seen in stone tools and were made exclusively from the dense long bones of large animals.
Sampling of bone tools found in Olduvai Gorge, with flaking marks illustrated to reveal efforts of the hominin toolmakers. (de la Torre, et.al/Nature).
The researchers concluded that the tools were fashioned from fresh bones, likely scavenged from carcasses of animals that had died of natural causes.
“The tools show evidence that their creators carefully worked the bones, chipping off flakes to create useful shapes,” said study coauthor Dr. Renata Peters, an associate professor of archaeology at University College London’s Institute of Archaeology. “We were excited to find these bone tools from such an early timeframe. It means that human ancestors were capable of transferring skills from stone to bone, a level of complex cognition that we haven’t seen elsewhere for another million years.”
The discovery indicates that early hominins were undergoing a technological shift around 1.5 million years ago. Before this study, researchers only associated this period’s advancements with stone tool development, but the inclusion of bone tools expands the understanding of early human innovation.
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“Prior to our discovery, the technological transition from the Oldowan to the Acheulean was limited to the study of stone tools,” de la Torre said. “This discovery leads us to assume that early humans significantly expanded their technological options, which until then were limited to the production of stone tools and now allowed new raw materials to be incorporated into the repertoire of potential artifacts.”
The ability to apply learned techniques to different materials suggests that early human ancestors possessed more sophisticated cognitive abilities than previously thought—which raises the possibility that they were responsible for other innovations that have yet to be discovered from the archaeological record.
Ancient Hominin Brilliance on Display
While previous discoveries of bone tools have been sporadic across Europe and Asia, the 27 tools found at Olduvai Gorge suggest a more organized and widespread production process. Although later bone toolkits found in Europe—dated to around 400,000 years ago—are more refined, the newly discovered tools appear to have been highly effective for heavy-duty tasks.
Olduvai Gorge, Tanzania. (Noel Feans/CC BY-SA 2.0).
Researchers remain uncertain about the specific uses of these bone tools. But they theorize they may have been employed for processing animal carcasses and manufacturing additional tools. Another mystery is which species of human ancestor crafted them, as no hominin remains were found alongside the artifacts. Evidence suggests that Homo erectus and Paranthropus boisei inhabited the region at the time, with the former perhaps being the more likely candidate to have engaged in bone-tool making activities.
The researchers believe the inspiration for bone tool production may have stemmed from the abundance of animal remains available, particularly during seasonal migrations. Additionally, in certain regions, stones suitable for toolmaking might have been less accessible, leading hominins to experiment with alternative materials. Since bone is more susceptible to decomposition, however, bone tools from so long ago would inevitably be difficult to find.
Dr. Briana Pobiner, a paleoanthropologist at the Smithsonian National Museum of Natural History who was not involved in the study, emphasized the importance of considering non-stone tools in research on human evolution.
“That there is a collection of 27 bone tools, and not just one or a few, suggests that hominins 1.5 million years ago (at least in this one place) were able to successfully transfer their knowledge of how to knap stone to knapping bone,” Pobiner said. “To me, this signals that toolmaking was becoming an increasingly important part of our ancestors’ lives. And once again, we should be looking in museum collections for more evidence of hominin behavior — in this case, bone tool manufacture — earlier than we might have previously expected.”
Top image: Tool made from an elephant’s humerus bone, found in Olduvai Gorge and dated to 1.5 million BC.
Source: Pleistocene Archaeological Laboratory/Spanish National Research Council (CSIC).
By Nathan Falde
