The earliest known instance of cannibalism among hominids occurred roughly 800,000 years ago, in the Gran Dolina cave of the Atapuerca Mountains in north central Spain. Eudald Carbonell of the University of Rovira and Virgili in Spain and colleagues found evidence of butchering on bones belonging to Homo antecessor, a controversial species that lived in Europe as early as 1.2 million years ago.
     Because no other hominid species has been found in the region at the same time as the butchered bones, the victims must have been eaten by their own kind.
     The new study, published online in the Journal of Human Evolution, shows how anthropologists use the behaviour of modern humans and primates to make inferences about what hominids did in the past, and demonstrates the limitations of such comparisons.
     Human cannibalism occurs in a variety of contexts - for nutritional value, as part of funerary rituals, or during warfare - and leaves different patterns in the archaeological record. When humans consume other humans for purely dietary reasons, the victims are often treated like any other prey. This is what the researchers found at Gran Dolina. The team also says there's evidence of cannibalism over an extended period of time - dozens or even hundreds of years.
     Some aspects of the case don't resemble those of contemporary human cannibalism, or cannibalism seen in Neanderthals or early modern humans living 100,000 years ago. For instance, 9 of the 11 butchered individuals at Gran Dolina were children or adolescents, compared with the largely adult victims of more recent human cannibalism.
     Young victims is a pattern seen among chimpanzees, where males from one group may kill and eat the infants of female chimps from another, when found near the boundary of their territory. Carbonell and his colleagues suggest the best explanation is territorial defence and expansion, and that a similar motivation may have been the behind Homo antecessor cannibalism, but offer no evidence that the Gran Dolina cannibals came from a different group than the victims.

Edited from Smithsonian.com (5 September 2012)