Ancient humans butchered one other 1.45 million years ago, here's proof

Examination of the cut marks

Pobiner first stumbled across this fossilized tibia, or shin bone, placed in the collections of the National Museums of Kenya’s Nairobi National Museum. At first glance, Pobiner knew these were cut marks, but to be certain, she forwarded the "molds of the cuts" to co-author Michael Pante of Colorado State University.

Pobiner did not provide any context for the cut marks or her original observational remarks about the fossil. And just requested Panet to see the marks on the molds. As per the official release, Pante created 3D scans of the molds and conducted a comparison with the database of 898 individual teeth, butchery, and trample marks. 

The 3D examination found that nine of the 11 marks definitely matched those wounds caused by stone tools. The researchers believe the remaining markings were most probably caused by a bite from a large cat, such as a lion.  

The authors assert that we cannot assume from cut marks alone that the ancient human who inflicted the marks also ate the leg, but this appears to be the "most likely scenario." 

“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,” added Pobiner. 

The fossil shin bone was initially identified as belonging to Australopithecus boisei, however, it was later reclassified to Homo erectus in 1990. Due to the scarcity of information on the bone, it is difficult to attribute it to any prehistoric human species. Furthermore, the usage of stone tools does not limit which species may have done the cutting. 

The team plans to analyze one of the earliest skull fossils discovered in South Africa in 1976. This skull most likely exhibits comparable cut marks or was created using the same processes as found in this latest study. This investigation might assist in narrowing down the human species that practiced cannibalism back then. 

The new study results have been reported in the journal Scientific Reports on June 26.

Study abstract:

Identification of butchery marks on hominin fossils from the early Pleistocene is rare. Our taphonomic investigation of published hominin fossils from the Turkana region of Kenya revealed likely cut marks on KNM-ER 741, a ~ 1.45 Ma proximal hominin left tibia shaft found in the Okote Member of the Koobi Fora Formation. An impression of the marks was created with dental molding material and scanned with a Nanovea white-light confocal profilometer, and the resulting 3-D models were measured and compared with an actualistic database of 898 individual tooth, butchery, and trample marks created through controlled experiments. This comparison confirms the presence of multiple ancient cut marks that are consistent with those produced experimentally. These are to our knowledge the first (and to date only) cut marks identified on an early Pleistocene postcranial hominin fossil.