Widespread cannibalism is usually not found in state-level societies, which have the means to tax and control surplus labor. Nevertheless, one of the most famous cases of cannibalism is that of the Aztecs, who sacrificed their prisoners of war and undoubtedly ate some of them. According to available evidence, most authorities agree that the partaking of human flesh is almost always a ritual practice. A minority of anthropologists, however, believe cannibalism emerged as a cultural response to chronic protein shortages. In contrast, various traditional cultures are known to have encouraged their members to eat part of their kinsmen's corpses out of respect for the deceased in a practice known as endocannibalism.
Some anthropologists believe that head-hunting evolved from cannibalism.
The term cannibalism is also used in zoology to describe species who prey upon their own kind, such as lions, crabs, ants, and some kinds of fish. See P. Brown and D. Tuzin, ed.