Extreme diets Cannibalism, or clickbait for paleoanthropology

Everybody’s quick to see a cannibal. The Romans thought the ancient Britons feasted on human flesh, and the British thought the same about the Irish. Not a few prehistoric finds have been attributed, evocatively if not accurately, to the work of ancient cannibals. In 1871, Mark Twain commented on the discovery of the bones of a primeval man who purportedly had been made a meal of by his peers: “I ask the candid reader, Does not this look like taking advantage of a gentleman who has been dead two million years?”

In today’s scholar-eat-scholar world of paleoanthropology, claims of cannibalism are held to exacting standards of evidence. Which is why more than a few eyebrows were raised earlier this week over a study in Scientific Reports asserting that a 1.45-mn-year-old fragment of shin bone — found 53 years ago in northern Kenya, and sparsely documented — was an indication that our human ancestors not only butchered their own kind, but were probably, as an accompanying news release put it, “chowing down” on them, too.

The news release described the finding as the “oldest decisive evidence” of such behavior. “The information we have tells us that hominids were likely eating other hominids at least 1.45 million years ago,” Briana Pobiner, a paleoanthropologist at the Smithsonian’s National Museum of Natural History and first author of the paper, said in the news release. “There are numerous other examples of species from the human evolutionary tree consuming each other for nutrition, but this fossil suggests that our species’ relatives were eating each other to survive further into the past than we recognised.”

The discovery of a portion of the presumed victim threw into relief one of the questions that keep paleoanthropologists up at night: When do marks on a bone indicate cannibalism? Or, put another way, How much pre-modern evidence is needed to prove a modern theory?

Dr. Pobiner, an authority on cut marks, had spied the half-tibia fossil six summers ago while examining hominid bones housed in a Nairobi museum vault. She was inspecting the fossil for bite marks when she noticed 11 thin slashes, all angled in the same direction and clustered around a spot where a calf muscle would have attached to the bone — the meatiest chunk of the lower leg, Dr. Pobiner said in an interview.

She sent molds of the scars to Michael Pante, a paleoanthropologist at Colorado State University and an author on the study, who made 3-D scans and compared the shape of the incisions with a database of 898 tooth, trample and butchery marks. The analysis indicated that nine of the markings were consistent with the kind of damage made by stone tools. Dr. Pobiner said that the placement and orientation of the cuts implied that flesh had been stripped from the bone. From those observations she extrapolated her cannibalism thesis.

“From what we can tell, this hominin leg bone is being treated like other animals, which we presume are being eaten based on lots of butchery marks on them,” Dr. Pobiner said. “It makes the most sense to presume that this butchery was also done for the purpose of eating.” In the study, Dr. Pobiner wrote that cannibalism was one possible explanation for the defleshed bone. But her quotes in the news release sounded more definitive and, to the chagrin of colleagues, inspired headlines such as “YABBA DABBA CHEW! Cavemen were butchering and eating each other 1.45 million years ago, scientists say.”

Franz Lidz is a journalist with NYT©2023

The New York Times