Researchers from the Smithsonian’s National Museum of Natural History have unearthed a chilling discovery: the oldest definitive evidence of human relatives butchering and likely eating one another. The discovery comes in the form of a 1.45-million-year-old shin bone from a relative of Homo sapiens, found in northern Kenya.

Cut marks on a 1.45-million-year-old shin bone suggest stone tools were used to butcher the leg for its meat.

Analysis of the fossilized tibia, or shin bone, revealed nine distinct cut marks consistent with damage inflicted by stone tools. These marks were located where the calf muscle would have attached to the bone, suggesting a deliberate attempt to remove flesh for consumption. Additionally, the cuts were all oriented in the same direction, implying they were made with a single stone tool in quick succession.

Three fossilized animal bones from the same region and time horizon as the newly analyzed tibia show similar butchery marks

While the cut marks point towards cannibalism, the exact nature of the act remains unclear. The fossilized bone cannot be definitively assigned to a specific hominin species, a group that includes modern and extinct humans as well as our close relatives. This ambiguity leaves open the possibility that one hominin species consumed another related but distinct species.

This newly discovered shin bone stands as the strongest contender for the earliest confirmed case of hominins eating each other.  However, a roughly 2-million-year-old Homo habilis or Australopithecus skull from South Africa has also been debated as a potential example of early cannibalism. Recent studies on the skull’s markings suggest they might be from natural processes rather than butchery.

A 3D model of the incisions on the shinbone helped scientists identify them as cut marks made with stone tools.

The lead author of the study, Briana Pobiner, a paleoanthropologist at the Smithsonian, stumbled upon this discovery while examining bones at the Nairobi National Museum in Kenya.  She was initially searching for bite marks from predators on fossilized bones but instead noticed these distinctive cut marks.

Pobiner believes the cut marks most likely indicate the hominin leg was butchered for food, not as part of a ritual. This conclusion is based on the location and orientation of the cuts, which align with practices observed in the processing of animal bones for consumption.

The fossilized tibia has nine cut marks inflicted with stone tools where a calf muscle would have been attached to the bone

The researchers also identified two bite marks on the bone, likely left by a large cat, possibly a saber-toothed cat native to the region at that time. The presence of these bite marks alongside the cut marks makes it difficult to determine the sequence of events. The hominins could have scavenged the remains after a big cat 𝓀𝒾𝓁𝓁, or they might have taken over the carcass after a big cat was forced to abandon its prey.

Pobiner emphasizes the importance of revisiting museum collections. This discovery highlights the potential for groundbreaking revelations by re-examining existing fossils with fresh perspectives and techniques.

This study underscores the value of revisiting museum collections with advanced analytical techniques, potentially uncovering new insights from well-studied specimens. Pobiner hopes future research will shed light on similar finds, such as the debated marks on a South African skull, further enriching our understanding of early hominin behavior and ecology.