However, scientists say there is not enough evidence to conclusively infer this as a sign of cannibalism
Scientists have identified possibly the oldest signs of cannibalism in humans' close relative species. A fossilized leg bone bearing cut marks made by stone tools might be the earliest evidence that ancient humans butchered and ate each other's flesh, Independent reported.
In the study published Monday in the journal Scientific Reports, researchers analysed nine cut marks on a 1.45 million-year-old left shin bone from modern human ancestors found in northern Kenya.
"This could be the oldest instance of cannibalism in a human relative species known with a high degree of confidence and specificity," they noted.
Notably, Briana Pobiner, a palaeoanthropologist at the Smithsonian Institution was combing through fossils at a museum in Nairobi, Kenya, looking for clues about the prehistoric predators that ate humans' ancient relatives.
Dr. Pobiner noticed what "looked to her like marks of butchery" and then compared the samples with controlled experiments.
While there were two bite marks from a big cat, the other nine marks were more similar to butchery marks found on animal fossils that appeared to be hunted and eaten by humans and their ancestors. She concluded that the cuts resembled those known to be made by stone tools.
Dr. Pobiner said: "The cuts are located on the shin 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. 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," Dr. Pobiner said.
While the cut marks themselves don't prove that human ancestors ate each other, Dr. Pobiner believes this is the most likely scenario. She added that the discovery was ''shocking, honestly, and very surprising, but very exciting''.
However, scientists say there is not enough evidence to conclusively infer this as a sign of cannibalism as that would require the eater and the eaten to hail from the same species. They also expressed that the use of stone tools also does not narrow down which species might have been doing the cutting.
Zeresenay Alemseged, a palaeoanthropologist at the University of Chicago, Illinois, said, ''The evidence is so sporadic at this point, all we're doing is connecting the dots. We are trying to go inside the brains of the early hominids, which means it's going to be very complex.''
Previous evidence of butchery among hominins has been found at sites in Europe and Africa, as per Nature.