While finding cut marks on animal bones is fairly common after the advent of stone tools in the archaeological record, finding cut marks on hominin bones is much more surprising. Dating to 1.45 million years ago from Koobi Fora, Kenya, a hominin tibia (shin bone), appears to exhibit multiple cut marks. The bone belongs to one of two hominin species: Paranthropus boisei or Homo erectus. The marks, which are clustered and facing the same direction, are all the same color as the surrounding bone, indicating that they were not made during excavation. Nine of the eleven marks were straight in trajectory and V-shaped, consistent with marks made by stone tools. The remaining two resemble lion tooth marks based on comparison to modern specimens, although they may have been left by another hominin. Without hominin tooth marks on the bone, cut marks are the strongest evidence of potential anthropophagy, or cannibalism - one member of a species eating another. 

These findings were presented in the journal Nature on June 26th, 2023, by Briana Pobiner and colleagues.