Man’s ancestors were cannibals who were eating each other at least 1.45 million years ago, suggests a new study.
Cut marks on a fossil leg bone belonging to a relative of modern humans were made by stone tools and could be evidence of cannibalism, say scientists.
Researchers have identified the oldest decisive evidence of humans’ close evolutionary relatives butchering and likely eating one another.
Paleoanthropologist Dr. Briana Pobiner and her colleagues found nine cut marks on a 1.45 million-year-old left shin bone from a relative of Homo sapiens found in Kenya.
Analysis of 3D models of the fossil’s surface revealed that the cut marks were “dead ringers” for the damage inflicted by stone tools.
It is the oldest instance of such behavior known with a high degree of confidence, according to the findings published in the journal Scientific Reports.
Dr. Pobiner, of the National Museum of Natural History, said: “The information we have tells us that hominins were likely eating other hominins at least 1.45 million years ago.
“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 recognized.”
Dr. Pobiner first encountered the fossilized tibia in the collections of a museum in the Kenyan capital of Nairobi while looking for clues about which prehistoric predators might have been hunting and eating mans’ ancient relatives.
She used a handheld magnifying lens to look at the fossilized bone for bite marks from extinct beasts when she instead noticed what immediately looked to her like evidence of butchery.
To figure out if what she saw were indeed cut marks, Dr. Pobiner sent molds of the cuts – made with the same material dentists use to create impressions of teeth – to co-author Dr. Michael Pante at Colorado State University.
She provided Dr. Pante with no details about what he was being sent, simply asking him to analyze the marks on the molds and tell her what made them.
Dr. Pante created 3D scans of the molds and compared the shape of the marks to a database of 898 individual tooth, butchery and trample marks created through controlled experiments.
The analysis positively identified nine of the 11 marks as “clear matches” for the type of damage inflicted by stone tools.
The other two marks were likely bite marks from a big cat, with a lion being the closest match.
Dr. Pobiner says the bite marks could have come from one of three different types of saber-tooth cats prowling the landscape at the time.
She said the cut marks, by themselves, do not prove that the human relative who inflicted them also made a meal out of the leg, but it seems to be the most likely scenario.
Dr. Pobiner explained that the cut marks are located where a calf muscle would have attached to the bone – a good place to cut if the goal is to remove a chunk of flesh.
She said the cut marks are also all oriented the same way, such that a hand wielding a stone tool could have made them all in succession without changing grip or adjusting the angle of attack.
Dr. Pobiner said: “These cut marks look very similar to what I’ve seen on animal fossils that were being processed for consumption.
“It seems most likely that the meat from this leg was eaten and that it was eaten for nutrition as opposed to for a ritual.”
While it may appear to be cannibalism to a casual observer, Dr. Pobiner said there is not enough evidence to make that determination because cannibalism requires that the eater and the eaten hail from the same species.
The fossil shin bone was initially identified as Australopithecus boisei and then in 1990 as Homo erectus, but today, experts agree that there is not enough information to assign the specimen to a particular species of hominin.
The use of stone tools also does not narrow down which species might have been doing the cutting.
Dr. Pobiner said the fossil could be a trace of prehistoric cannibalism, but it is also possible that it was a case of one species chowing down on its evolutionary cousin.
She says none of the stone-tool cut marks overlap with the two bite marks, which makes it hard to infer anything about the order of events that took place. For instance, a big cat may have scavenged the remains after hominins removed most of the meat from the leg bone.
It is equally possible that a big cat killed an unlucky hominin and then was chased off or scurried away before opportunistic hominins took over the kill.
One other fossil – a skull first found in South Africa in 1976 – has previously sparked debate about the earliest known case of human relatives butchering each other. Estimates for the age of that skull range from 1.5 to 2.6 million years old.
To resolve whether the fossil tibia she and her colleagues studied is indeed the oldest cut-marked hominin fossil, Dr. Pobiner said she would like to reexamine the skull from South Africa.
She added: “You can make some pretty amazing discoveries by going back into museum collections and taking a second look at fossils.
“Not everyone sees everything the first time around.
“It takes a community of scientists coming in with different questions and techniques to keep expanding our knowledge of the world.”
Produced in association with SWNS Talker
Edited by Saba Fatima and Newsdesk Manager
