Nearly a million and a half years ago, a group of human relatives appear to have made a meal of one of their own. Cut marks on an ancient shin bone from a site in northern Kenya show signs of having been butchered to separate the meat, possibly representing the earliest known instance of cannibalism among hominins.
The butchering was likely performed by individuals who needed the food, says paleoanthropologist Briana Pobiner of the National Museum of Natural History in Washington D.C. "People are hungry, and they’re eating dead people to feed themselves.”
While this looks like clear evidence for 1.45-million-year-old cannibalism among our ancestors, neither the species of the butchers nor the butchered could be determined. It is likely they were all Homo erectus, the dominant hominin in the area at that time, but they might have been Homo habilis or even Paranthropus boisei.
If one species ate another, this technically wouldn’t have been cannibalism but instead an instance of anthropophagy, or eating hominin flesh, says Pobiner, the lead author of research published in Scientific Reports describing the discovery. All the same, she notes, these hominins may have looked somewhat alike, and the butchers were probably not choosey about who they were eating.
Among our own species, Homo sapiens, there have been many cultural taboos against cannibalism for thousands of years. As a result, instances of human cannibalism have often been ritualized to overcome those taboos. But these earlier hominins were probably not attaching any such significance to the meal, Pobiner says. “I don’t think we’re seeing that this far back.”
Whatever the reason for the butchery, Pobiner almost didn’t believe her discovery. “It was one of those moments when you look at something and go: No way,” she says.
In 2017 Pobiner traveled to Kenya to examine dozens of hominin bones housed in the National Museums of Kenya in Nairobi. She was looking for animal bite marks on the bones, which would indicate early hominins were eaten by African predators such as hyenas or wildcats.
But she didn’t find any bite marks. Instead she found what looked like cut marks on a hominin shin bone, which was discovered in 1970 in the Turkana region of northwestern Kenya by the famed British paleoanthropologist Mary Leakey.
Pobiner had seen such marks before. “I’ve studied hundreds of fossil animal bones from the same time period in the same region that have butchery marks,” she says. “So I knew immediately what they were.”
She then made impressions of the cut marks with the material that dentists use to make molds of teeth and sent them to her colleague Michael Pante, a paleoanthropologist at Colorado State University and co-author of the new study, without saying what she thought they were.
Pante and Trevor Keevil, a doctoral student in anthropology at Purdue University and study co-author, then made 3D scans of the mysterious marks and compared them to a database of 898 tooth, butchery, and trample marks made in controlled experiments. Their analysis showed that at least 9 of the 11 cut marks had been made by stone tools on the 1.45-million-year-old bone.
There’s no reason for such butchery unless the meat is to be eaten, and Pobiner says it seems the diners were trying to separate the meaty calf muscle from the bone. “They’re butchering them in the way that they butcher other animals,” she says.
Hungry for meat
Hominins have been eating hominins for more than a million years, and this may be the earliest evidence, says archaeologist and anthropologist James Cole of the University of Brighton in the United Kingdom, who wasn’t involved in the new research.
Before now, the earliest clear evidence for butchery marks on hominin bones was from the Atapuerca archaeological site in Spain, Cole says. Those bones were estimated to be more than 800,000 years old.
But “I see no problem in this behavior being older,” says Cole, who has studied hominin cannibalism. “It almost certainly was, given the abundance of the practice in the animal world.”
Why these hominins ate another is a trickier question to answer. “It is difficult to discern whether this was for nutritional consumption or for a more complex cultural activity, such as for ritual purposes,” says paleoanthropologist Michael Petraglia, director of the Australian Research Center for Human Evolution at Griffith University in Brisbane, who was not involved in the new study.
Nevertheless, Pobiner thinks this was a case of strictly nutritional cannibalism, or perhaps nutritional anthropophagy, that was carried out because the butchers needed food. There’s no evidence of burials or other ritualistic behavior among Homo erectus or other hominins at this time, so it’s unlikely they had a ritualistic approach to eating people, she says.
Cannibalistic rituals may be unique to our own species, with some inferred from Paleolithic Homo sapiens remains. More recently, cannibalism was part of Aztec religious beliefs, where strict rules applied to who could be eaten and who could do the eating. Even instances of cannibalism for survival, such as in shipwrecks, involve stories of ritualized behavior such as the drawing of lots.
There’s also evidence of cannibalism among Neanderthals, but it appears to have been purely nutritional. “It seems you get this more ritual cultural aspect to cannibalism with modern humans,” Pobiner says.
The researchers haven’t ruled out the possibility that the hominin victim was hunted for its meat, but it’s also possible it died of other causes and then was eaten. Modern apes like chimpanzees sometimes kill each other in territorial disputes and then eat the dead, Pobiner adds, and they seem to treat the bodies as just a source of meat.
The new research illustrates how much we can learn from previously discovered bones. It “shows that new behavioral information can be obtained with modern observations and the application of novel technologies to old museum collections,” Petraglia says.
“Some of the best discoveries have already been found, but perhaps not fully recognized yet,” Cole adds.
Pobiner, too, stresses the value of studying old fossils with new scientific techniques. “This really underscores the importance of going back and looking again at museum collections,” she says, “because you might find things that are unexpected.”