Thus cannibalism has conditioned the evolution of the human species

Among the Homininaethe hominid subfamily that includes humans, chimpanzees, and gorillas, along with all the ancestors of each of these three species, cannibalism has been documented among both humans and chimpanzees. For gorillas, there is only one observation from the 1970s, when primatologist Dian Fossey found the remains of two gorillas in the feces of a gorilla mother and her daughter; since then, nothing. Cut marks on 800,000-year-old hominin remains from Atapuerca, Spain, and on more recent Neanderthal bones suggest that in our evolutionary branch cannibalism was widespread, although the nutritional value of this type of diet is not that important compared to what can be obtained from alternative prey. In our own species, there are even signs of this behavior in the human genome: a mutation has been found in Papua New Guinea that protects them from kurua prion disease transmitted through the ritual cannibalism they perform on the dead.

Aside from cannibalism, the consumption of the flesh of other living hominins by modern humans is a well-known fact: despite their status of protected species, in Africa you can eat chimpanzee and gorilla meat. Conversely, chimpanzees frequently hunt other monkeys and prosimians and, in some populations, use pointed sticks, like spits or spears, to capture their prey, tools obtained through steps that include preparing the tip with the teeth. This behavior has been documented hundreds of times, proving that it is not accidental. The picture, as regards both our species and those evolutionarily closest, is therefore clear: when not the conspecifics directly, we habitually and extensively prey on any type of other monkey, more or less similar to us.

A new article confirms this state of affairs, proving that even in very ancient times, i.e. about 1.45 million years ago, at the beginning of the Pleistocene, hominins slaughtered and presumably consumed other hominins as food. The study authors were initially conducting a study to identify the predators of hominins from those remote times by analyzing their bones. These, in fact, maintain specific chewing signs in the case connected to the consumption of meat, signs that can frequently be traced back to the type of animal that ate a very ancient body. Well, on a tibia found in Kenya, belonging to an uncertain species but certainly connected to us (an australopithecine or perhaps Homo erectus), traces of a bite by a large feline have been identified, through the comparison of the visible signs on the bones with a database of 898 referable to different possible causes. However, the signs of the felines – such as the saber-toothed tigers that frequented Kenya at the time – are only the minor part of the markings present on the tibia: the bulk, or at least 11 other sets of signs, are instead undoubtedly associated with the cutting with stone tools.

Previous research of animal remains with slaughter marks at the same locality to which the findings discussed by the authors refer shows that around 1.5 million years ago, present hominins frequently used stone tools to flesh, disarticulate and extract marrow from a variety of animal species and of different sizes and coming from different habitats: given the way in which the tibia in question was processed, i.e. in a very similar way to what has been observed for other types of prey, the stripping does not seem to have a significant ritual, but instead corresponds to an opportunistic eating behavior, for the sole purpose of obtaining food.

It is not possible to know who made those cuts, whether individuals of the same species, in a case of cannibalism, or of different species, as happens today when chimpanzees prey on other monkeys; moreover, it is not known if the remains of the leg were subsequently consumed by some big feline, or if instead the hominins that probably fed on them stole the prey from the latter. In any case, however, the information we have thanks to this new study seems quite clear: 1.45 million years ago, in the midst of our ancient evolution, hominins ate hominins, not unlike what we observe today, when African forest hunters prey on chimpanzees. That is, at least some of our behaviors are very ancient, probably pre-human, and have contributed to competition between different species and between individuals within species.