Our Human Relatives Butchered and Ate Each Other 1.45 Million Years Ago

Craving the meatiest chunk of the lower leg, a Paleolithic butcher struck again and again with a sharp stone blade, removing flesh from bone with practiced skill. When the job was done, this unknown ancient relative of ours was rewarded with a satisfying feast—from the body of another early human.

A recent discovery in a Kenyan museum—previously unnoticed cut marks on a 1.45-million-year-old shin bone—may be the oldest evidence of ancient human relatives butchering and presumably eating each other. Nine distinctive marks, oriented in the same direction, show repetitive cuts in the place where calf muscle attaches to bone, revealing a stone tool methodology typically used to remove meat. Two bite marks show a big cat also chomped on the bone at some point.

Because only the shin bone survives, researchers can’t say just which ancient species of Homo sapiens relative was cut up and devoured. They also don’t know whether the same species or a different relative stripped and presumably ate the calf muscle. If the two were the same species, the find may represent the earliest known example of cannibalism. If not, the grizzly tableau still represents one evolutionary cousin having another for dinner—and not as a guest.

“We just know that some tool-wielding hominin came and cut meat off of that bone,” says paleoanthropologist Briana Pobiner of the Smithsonian’s National Museum of Natural History, who studies the evolution of human diet. “The most plausible explanation is that they did that to eat it.”

Pobiner is a co-author of a study on the find published Monday in Scientific Reports.

Famed anthropologist Mary Leakey found the fossil in 1970 among many others in Kenya’s Turkana region. Pobiner came upon it in 2017 while examining collections in Kenya’s Nairobi National Museum. She was searching through bones of ancient human relatives for bite marks to learn more about which ancient animals preyed upon them, never expecting to find another human species among those predators—or at least among the scavengers.

“I’ve seen tool marks on many animal fossils from this area and time period, so I thought, Wow, I definitely know what this is,” Pobiner recalls. “But I also thought—Surprise! This is definitely not what I thought I would find.”

Although Pobiner thought the cut marks were clearly recognizable, she subjected them to a rigorous analysis. Using the same materials that dentists employ to make impressions of teeth, she molded the cut marks and sent them to co-author Michael Pante, a paleoanthropologist at Colorado State University. She shared no background information on where they were from or what she suspected they were.

Pante and Trevor Keevil, a researcher at Purdue University’s Laboratory for Computational-Anthropology and Anthroinformatics, worked with a database of nearly 900 different tooth, butchery and other bone markings. These bone markings are modern, including bite marks from various carnivorous animals and cut marks from tools. Every one is of known origin—the better to identify unknown examples by comparison. Pante made 3D scans of the shin bone molds and compared them with his database entries to learn that 9 of the 11 marks were clearly created by stone tools, while two others were likely made by some variety of big cat. “The work that Michael Pante and Trevor Keevil did with all the modern marks is hugely important,” Pobiner says. “That’s how we can use the present to understand the past.”

But many aspects of the intriguing find remain beyond our understanding, including the identities of the two individuals involved—the victim and the butcher.

Since the shin bone’s discovery, researchers have suggested the dead hominin was a Paranthropus boisei or Homo erectus, but there’s no consensus as of yet. Scientists also don’t know what motivated the butcher. Palmira Saladié Ballesté, an archaeologist at the Catalan Institute of Human Paleoecology and Social Evolution, says researchers have a difficult time inferring much about the behaviors involved in the incident when they’re left with just a single bone showing signs of butchery. “However, in any case, it would involve the defleshing of a technologically advanced hominin by another technologically advanced one,” she says. “From this perspective, it can be considered cannibalism.”

And the human butcher wasn’t the only individual who attempted to make a meal of this particular leg bone. The two bite marks, apparently those of a big cat, are closest to matching the lion among living species. But they may have been the work of saber-toothed carnivores or other extinct cats, which are no longer around to contribute to the bite database.

This unknown cat may have killed the unfortunate victim and chewed on its leg before being driven off by humans who later took charge of the body. Or hominins could have killed and butchered the unfortunate victim before big cats got to the scraps.

Or maybe no violence was involved. Someone might have simply died, and then scavengers of several species took advantage of a free meal. “Lions do a lot of scavenging, and there’s no reason to think that any big predator on the ancient African savanna wouldn’t have also scavenged—including early humans,” Pobiner says.

Although more than 1,300 species, including some primates, are cannibalistic, the practice is considered taboo across most modern human societies. Researchers can’t be sure how our prehistoric relatives felt about it, or the various reasons that they ate their own kind in different times and places. But, perhaps surprisingly, the evidence shows that it wasn’t all that uncommon.

A South African skull that may be 1.5 million to 2.6 million years old is another candidate for the dubious honor of being the first early human relative known to have been cannibalized by its peers. But Pobiner notes that the skull’s age is uncertain, as are interpretations of the cut marks found below its right cheek bone. Scholars have disagreed whether these marks were made by stone tools, and, if so, if they would have been related to cannibalism—the relative lack of edible flesh in the skull complicates this hypothesis.

A few other such examples exist from this early period of human development. Then, beginning about half a million years ago, scientists start to see cannibalism happening not infrequently in the fossil record among our relative species, particularly Neanderthals and H. sapiens. “The interpretation with Neanderthals, particularly, is that they lived in marginal environments where they were food-stressed,” Pobiner notes. “We don’t really see evidence of aggression or rituals. We see Neanderthals being butchered and dumped in pits with other animals. So we think they were probably just eating people because they were food.”

Silvia Bello, an anthropologist at the Natural History Museum in London, thinks cannibalism might have been more common than expected. Many human remains aren’t preserved at all, and butchery marks aren’t always visible, she notes. “Some tissue may be eaten without leaving marks on bones, or bodies could have been completely consumed, as is the case of the Wari in South America, therefore leaving no evidence.”

Few would suggest that humans frequently hunted each other down for food. Even if they had no qualms about killing and eating each other, easier, less intelligent prey would have likely formed the basis of their diet. Besides, when University of Brighton archaeologist James Cole broke down the nutritional value of human meat, he found our bodies’ caloric values so low that other Paleolithic prey would have been far more desirable.

Instead, cannibalistic meals may have been dietary supplements. Our ancestors simply took advantage of the deceased as easy pickings—at least during earlier stages of our evolution. Other, younger sites from a wide range of time do show evidence of what appears to be ritual or cultural cannibalism, both within groups and representing aggression between groups.

At Gran Dolina, Spain, 11 young Homo antecessor individuals were butchered, and their brains apparently consumed, over a period of time about 800,000 years ago. Some experts, drawing parallels with chimpanzees that protect their territory by killing and eating the young of neighboring groups, interpret those Spanish remains as the result of similar conflicts. At England’s Gough’s cave, human bones that had been defleshed and chewed some 15,000 years ago also bear ritualistic markings that suggest cannibalism there may have begun to take on ceremonial or symbolic aspects.

Bello thinks that once Neanderthals and modern humans began to develop funerary rituals 100,000 years ago, cannibalism may have acquired ritualistic components, becoming more than a meal. “The reasons why this shift [occurred] may be the same as the reasons why humans started to bury and ritualize bodies,” she notes.

Though cannibalism exists in modern times, most humans find it a distasteful prospect that they’d rather not dwell on. But for those delving into the eat-or-be-eaten environments in which our ancestors survived, the topic keeps coming up, and finds like Pobiner’s push it back further toward our evolutionary origins.

“It’s interesting to think,” she notes, “about how long our ancestors and relatives have been seeing other people as potential food.”