• The presence of streaks on a 2.4 million-year-old Australopithecus skull could suggest an act of cannibalism, according to our partner The Conversation.

  • But whether he obeyed for food, political, ritual and / or cultural purposes, the cannibalism of the earliest representatives of the genus

    Homo

    was probably not entrenched.

  • The analysis of this research was carried out by Raphaël Hanon, post-doctoral fellow in archaeozoology and taphonomy at the University of the Witwatersrand (Johannesburg, South Africa) and at the National Museum of Natural History (Paris)

This is the ultimate transgression, that which consists in the consumption of an individual of his own kind.

Beyond the act itself, an underlying symbolism is sometimes attributed to it, which can represent an assimilation of the other and its specificities.

The use of cannibalism is therefore considered inhuman, leading to dehumanization and condemnation of the peoples who practice it.

However, experts agree on this point, the cannibalistic phenomenon is a complex system.

But where does this practice come from?

During the year 2000, three eminent American researchers published the description of traces observed on the surface of a 2.4 million year old Hominina bone.

In the article published in the

American Journal of Physical Anthropology

, the authors hypothesize that these are the oldest proven traces of the practice of cannibalism in the human lineage.

Australopithecines or

Homo

 : the first cannibals?

In August 1976, paleoanthropologists Alan R. Hughes and Philip V. Tobias discovered a partially preserved skull, named Stw 53, from the famous Sterkfontein site in South Africa.

It is actually a real puzzle since nine pieces are identified as belonging to the same incomplete specimen.

From the study of his anatomy, the individual probably belongs to the Hominina sub-tribe (the Hominina sub-tribe groups together all the taxa belonging to the human line since its separation from that of the chimpanzees). With the Panina sub-tribe, corresponding to our sister group which brings together representatives of the chimpanzee lineage, they form the Hominini tribe. Specialists are not yet certain whether to place the separation of the two lineages at the level of the Hominini / Panini tribe or the Hominina / Panina sub-tribe. However, the exact identification of the skull is debated. At the time of its discovery, it was attributed to the genus

Homo

, probably belonging to the species H. habilis.

Subsequently, other work suggested that it would actually be closer to the genus

Australopithecus

. But from cladistic studies, which allow the reconstruction of phylogenetic trees, crossed to the approaches of comparative anatomy, it would seem that we are facing a representative of the species

H

.

habilis

.

Beyond its taxonomic attribution, the dating of the skull is also uncertain.

This is particularly due to the difficulty we have in correctly dating the deposits with very complex stratigraphy, that is to say the stacking of sedimentary layers, often upset, that we find in South African caves.

By taking into account all the ages proposed for this fossil, it appears that the latter was buried within the cave between 2.6 and 1.5 million years ago.

Proposed reconstruction of the Stw 53 skull according to the work of Curnoe and Tobias (2006) © Wikimedia CC BY-SA

During the late 1980s and 1990s, three American researchers examined the skull with a magnifying glass. They then discovered a series of short linear striations on the inner surface of the zygomatic bone (anatomical nomenclature varies according to the taxonomic group studied. In non-human vertebrates, the zygomatic bone is commonly referred to as the jugal or malar bone. corresponds to the bone of the cheekbones. According to them, these cutmarks correspond to “cut marks inflicted by a lithic tool such as the sharp edge of a flake.” The cutmarks are located on the insertion region of the masseter muscle (

masseter

) which participates in the movement of the mandible (manducator apparatus) and thus allows chewing.

The presence of striae in this very specific region of the skull would then indicate a desire for disarticulation of the mandible.

The authors suggest several hypotheses to explain the presence of these cutmarks such as cannibalism, an act of maintaining the body and / or a funeral act.

These hypotheses have important implications for the behaviors of the first representatives of the genus

Homo

because these striations would represent the first bone modifications of human origin observed on human fossils.

Apart from Sterkfontein, the oldest site to have yielded Hominina remains with such traces come from the Gran Dolina site, at Atapuerca in Spain, and are dated only between 900,000 and 800,000 years ago.

Details of the marks observed on the surface of the Stw 53 fossil © S. Prat (CNRS)

This is why in 2015, we decided to unravel the mystery of Stw 53. Our question was therefore the following: are the traces observed on the surface of the fossil really cut marks of anthropogenic origin? In order to test the hypothesis of the American team, we had to set up a protocol aimed at verifying whether these traces can only be created by human intervention or also by other processes. In other words, is it conceivable that these marks are created by natural physical or biological phenomena?

Among these phenomena, we are thinking in particular of carnivores, which have played a major role in the accumulation and modification of bone remains found in South African caves. Large rodents, such as porcupines, can also leave marks on bones by gnawing on them. Finally, the fossil could have undergone significant compression due to the accumulation of sediments within the cave (sediment compression) or the repeated passage of animals (trampling), coupled with the presence of many small stone chips around it. , and thus keep the eternal scar of the past.

First, we obtained a high-precision resin cast of the skull which we observed using a binocular magnifier as well as a scanning electron microscope.

This allowed us to obtain very high resolution photos and thus better describe the morphological characteristics of the tracks.

Secondly, we applied the same observation method to bone remains preserved in the taphothèque of the Institute of Human Paleontology (IPH) in Paris (a taphothèque is a collection of biological or mineral objects documenting the action of various phenomena).

In the case of the IPH taphothèque, it is possible to observe bones bearing traces of flint tools (butcher's marks), carnivorous fangs, rodent teeth or even plant roots.

Setting up the trampling experiment. Pig bones were placed in different sediments, here flour which is a neutral non-abrasive sediment, in which are placed flint shards © Raphaël Hanon

We selected remains with anthropogenic, carnivorous and rodent markings. Thirdly, we designed an experiment aimed at recreating marks of trampling and butchery. To do this, we placed the bones of pigs in sediment bins in which we had sometimes mixed shards of flint. Then, we voluntarily walked several times in these bins in order to recreate a “trampling” effect on a smaller scale. The butchery was also carried out using flint shards from the region where the fossil was found, in order to get as close as possible to the original conditions. The marks resulting from the experiment were then analyzed using the same methodology as that applied for the Stw 53 fossil.The results from our analysis show that the morphological variation of the marks observed on Stw 53 are consistent with a natural, non-anthropogenic origin.

Other sources of information, contextual this time, also converge on our hypothesis.

Clarke notably highlighted the presence of a block of flint near the skull when it was discovered, which could be the cause of the origin of the marks.

Moreover, if it is indeed an act of disarticulation of the mandible, why do not we also find marks on the preserved temporal bone?

Removal of the masseter muscle would require treatment of these two attachments, on the temporal and zygomatic, which does not appear to be the case here.

Photograph of the “Cradle of Humankind” in South Africa, the region where the Stw 53 fossil was found © Raphaël Hanon

Finally, we observe an absence of anthropogenic traces on Hominina remains up to 900–800,000 years ago, so the validation of an exceptional hypothesis requires exceptional facts.

We are faced here with an astonishing convergence of evidence towards a natural origin of the marks observed on this skull.

By taking the party to apply the principle of Ockham's razor, or the principle of parsimony, it is preferable to keep the most economical hypothesis in supposition.

Today, all cannibals?

The title of this article is loosely based on a text published in 1993 by Claude Lévi-Strauss.

Apostrophed "We are all cannibals", the article addressed the different modalities of cannibalism and questioned its instrumentalisation, its barbarization, on the part of Western societies to serve their interests.

He thus evoked, from an ethnological point of view, the place that could have transplants or blood transfusions in a broad definition of cannibalism.

He thus came to the conclusion that cannibalism had been clothed in a diabolical garb, sometimes without reason, thus becoming a tool of judgment and of justification towards the enslavement of certain human populations.

We therefore come to justify one violent act by another.

Claude Lévi-Strauss wrote in this article:

"Let us reverse this tendency and seek to perceive the facts of cannibalism in their full extent. In ways and for extraordinarily different purposes depending on the time and place, it is always a question of voluntarily introducing into the body of human beings parts or substances from the bodies of other humans. Thus exorcised, the notion of cannibalism will now appear quite commonplace. "

How does the archaeological case of the Stw 53 skull fit into this debate?

The attribution of a cannibalistic act to the Australopithecines, or even to the first representatives of the genus

Homo

, is in part to accept the hypothesis of a rooting of cannibalism within our evolutionary history, whether it is at food, political, ritual and / or cultural purposes.

However, as we have seen, this hypothesis is confronted

de facto

with our distorted view of the cannibal phenomenon, often wrongly imagined as an extremely violent phenomenon.

This violent and bloodthirsty past of humanity is reminiscent of Raymond A. Dart's theory of the “killer monkey”.

Our dossier "Cannibalism"

However, archaeological and osteological data do not currently allow us to confirm the existence of the practice of cannibalism in the first representatives of the genus

Homo

. The fossil record therefore indicates that cannibalism is not a practice common to the entire human line, nor even within the genus

Homo

. This practice appears, according to current data, around 800,000 years ago in

Homo antecessor

, and will be more intensely implemented by

H. neanderthalensis

.

So, almost thirty years after Lévi-Strauss's article, we can still ask ourselves this question: are we,

in fine

, all cannibals?

Archeology has its limits and from here we leave the question open to philosophy.

Science

Homo sapiens: why our ancestor just took a 100,000 year old shot

Science

The word would be prior to the appearance of Homo sapiens ... and it is the monkeys who tell us!

This analysis was written by Raphaël Hanon, post-doctoral fellow in archaeozoology and taphonomy at the University of the Witwatersrand (Johannesburg, South Africa) and at the National Museum of Natural History (Paris).


The original article was published on The Conversation website.

Declaration of interests

Raphaël Hanon received funding from the DST-NRF Center of Excellence in Palaeosciences.

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