Archaeologists discover humanity’s first knives, carved from bone 1.5 million years ago

On Wednesday, a surprising technological breakthrough was presented: the oldest bone tools ever discovered. Nearly 30 knives, some up to 40 centimeters long, were carved by our ancestors 1.5 million years ago in the Olduvai Gorge, Tanzania. Led by Madrid archaeologist Ignacio de la Torre, the team behind the find believes that this new set of tools, made from an unusual material, represents a “qualitative leap in the cognitive abilities” of Homo erectus, the ancestor of our species, Homo sapiens.

The first knife was uncovered in 2015. It was a dark, pointed object that appeared to have been deliberately sharpened. De la Torre, a researcher at the Spanish National Research Council (CSIC) and co-director of the excavations with Jackson Njau from Indiana University, initially doubted it could be a human tool. However, in 2018, the team uncovered several more knives. They were larger, with more pronounced edges and points. Suddenly, “it was crystal clear,” recalls De la Torre. The discovery was published Wednesday in Nature, a leading journal in the world of science.

These are humanity’s first knives, says the 48-year-old CSIC researcher. Until now, the oldest known bone tools were from half a million years ago and had been found in Europe and Asia. This new discovery, the study emphasizes, “sheds new light on the almost unknown world of early hominin bone technology.”

All the daggers have a single serrated edge, sharpened with stones, and a pointed tip for stabbing. Much like the knives in our own kitchens today, many of them are blunt from use.

The first thing that surprises observers when handling one of these knives is its weight, which can reach up to 1.7 kilos. This is partly due to the fact that the bone has fossilized and turned into stone. Researchers rule out the possibility that these remains could simply be bones that were broken unintentionally. Under a microscope, the marks left by the stone hammers used to sharpen them are unmistakable, they argue.

Researchers have also attempted to recreate these tools using Yoyo, an African elephant that died in 2024 at the Barcelona Zoo, one of the oldest of its species. The animal was skinned and prepared for conservation as a scientific specimen by paleoanthropologists from the Catalan Institute of Human Paleoecology and Social Evolution (IPHES) in Tarragona. These experimental knives, carved from Yoyo’s humeri and femurs in the Olduvai style, are lighter, weighing about one kilo, and provide insight into what the original weapons may have been like, though the research is still ongoing.

The Tanzanian site is located by an ancient waterhole, where hominids likely found dead gazelles and hippos. However, most of the knives are made from elephant bone, which is harder than that of other large mammals, suggesting that hominids may have transported them from elsewhere.

The new tools coincide with one of humanity’s earliest technological revolutions. From about 2.5 million to 1.5 million years ago, our species’ technology primarily consisted of small stone chips sharpened by blows to cut meat. This period marked the emergence of the Acheulean tool, a new concept based on heavier stones that functioned as hand axes. These tools made it easier to break bones down to the marrow — a rich source of calories to fuel an expanding brain. The new findings complement the technological repertoire of the time, adding long knives that provided Homo erectus with an adaptive advantage.

Homo erectus was the first human species with a wingspan similar to modern humans and a brain of significant size. They were the first to leave Africa and reach Europe, where they gave rise to native species like Homo antecessor from Atapuerca, in Burgos, and the Neanderthals, the species closest to us. They also ventured into Asia, where they survived until as recently as 100,000 years ago, making them the longest-lived human species on Earth.

In 2019, De la Torre received a prestigious €2.5 million grant from the European Union to investigate the cultural and biological adaptations of the humans who led these early migrations. With the new collection of bone tools preserved in his laboratory in the basement of the Center for Social and Human Sciences in Madrid, he believes he now has part of the answer before him.

These bone tools were carved following an established pattern, suggesting a deep knowledge of anatomy and an understanding of which bones were suitable for such use. According to the dating, the tools were crafted over the course of several years, explains De la Torre. This implies that knowledge was transmitted between individuals to create a technology that not only helped them survive, but also allowed them to defend themselves and conquer new territories. While these humans were likely not yet hunting, “it seems clear that they were capable of scaring off any competitors to access” the carcasses, De la Torre explains.

The Olduvai Gorge has geological and climatic conditions that are ideal for preserving fossils. However, these may not be the only knives of their kind. The CSIC researcher believes similar tools may have gone unnoticed at other sites. One of his future goals is to review existing archives in search of new bone knives.

“There may be more; we shouldn’t rule it out,” agrees paleoanthropologist Juan Luis Arsuaga, co-director of Atapuerca. The scientist, who was not involved in the study, explains: “Before these 1.5-million-year-old findings, only a few loose, unmodified tools were known, such as the use of horns to extract termites from their nests,” dating back around two million years. “This study highlights the existence of systematic manufacturing,” similar to what was already observed with stone tools, like double-edged axes, he adds. The research “develops a methodology to identify this type of tool, which could be applied to other sites,” he concludes.

Archaeologist Jordi Rosell recalls the ellipsis that encapsulates the entire history of human evolution in less than five minutes. A hominid grabs a long bone and realizes he can use it as a weapon. He then throws it into the air, and it transforms into a spaceship. This is the opening scene of Stanley Kubrick’s 2001: A Space Odyssey (1968).

Ten years earlier, Australian anthropologist Raymond Dart had theorized about osteodontokeratic culture. The term referred to the use of bones, teeth, and horns to make tools, with which Australopithecus prometheus, a possible human ancestor living in Africa 3.6 million years ago, was already capable of hunting. The bone, Rosell reasons, could have been the first weapon — an idea he values in light of the new discovery.

“Until now, only double-edged axes made of elephant bone were known. These new findings reveal a much more varied spectrum than we had thought.” “I’m convinced that these hominids could hunt and combined this skill with scavenging. We know they were often the first to reach the carcasses. We assumed the animals were already dead, but what if they were the ones who killed them?” he concludes.

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