Neanderthals were very similar to us, making their extinction a mystery. What advantage did we have over them that allowed us to survive? However, new research suggests that we might not have had edge over the Neanderthals. Instead the Neanderthals may have driven themselves extinct with cannibalism.

There is plenty of evidence showing that our sister species would kill and eat each other. Perhaps during times of environmental stress. Although this might have allowed Neanderthal groups to survive on their own, it would be an obvious disadvantage when they had to compete with a non-cannibalistic species. Like we are (for the most part).

Neanderthal cannibalism

Evidence for Neanderthal cannibalism comes from several archaeological sites throughout Europe. This evidence is so abundant researchers have known about it for more than 100 years.

Bones from X, with cutmarks indicating cannibalism

Bones from Moula-Guercy, with cutmarks indicating cannibalism

One of the largest cannibal sites is Krapina, Croatia, which contains more than 100 Neanderthal bones (possibly representing as many as 14 individuals) with cutmarks on them. These cutmarks were suspiciously similar to those found on the animals Neanderthals butchered and ate.

Several sites in France also tell a similar story. Moula-Guercy, in the Ardeche, contains half a dozen Neanderthal remains that appear to have been ripped apart and butchered by other Neanderthals.

Curiously, at many of these sites the “victims” were treated with a degree of respect. At Krapina and other nearby locales, the bones seem to have been deliberately buried after they had been butchered. This stands in stark contrast to how Neanderthals normally treated their prey. Reindeer bones were often left scattered around the floor of the camp, for example.

Cannibalism wasn’t unique to Neanderthals either. The (pre)history of this morbid behaviour stretches back perhaps a million years. In fact, some of the earliest Europeans were already engaging in cannibalism. Some of the hominin bones from Atapuerca, Spain, contain the tell-tale cutmarks of butchery. This early case of cannibalism tells a rather chilling tale. It appears that infants were the primary victim. This is similar to the pattern seen when one chimpanzee group invades and attacks another.

The model

Cannibalism doesn’t seem like a particularly smart move if your species is trying to survive. So a group of researchers wondered: what would be the benefits of this behaviour that might drive it’s evolution. And could the negative side-effects put them at a disadvantage when competing with modern humans?

To answer these questions they came up with fancy agent-based model. It placed virtual Neanderthals in an environment with varying levels of resources and organised them into small communities. Each of these had a preference for cannibalism, which could increase or decrease through natural selection.

The cannibals (red) at the end of the first simulation dominate the regions with the highest resource areas (green)

The cannibals (shades of red) at the end of the first simulation dominate the regions with the highest resource areas (shades of green)

After letting these virtual Neanderthals run around for a while (and sometimes eat each other) they identified circumstances where cannibalism would become more common. In particular, cannibalism provided an evolutionary benefit when the Neanderthals were living in low quality environments. In these cases, cannibalism was used to supplement the food supply (and decrease competition). It eventually became universal as non-cannibals just couldn’t compete.

However, when a non-cannibalistic group entered the fray things changed. Cannibalism increases individual fitness. However, this constant infighting keeps the number of cannibals small. Thus when virtual modern humans (who didn’t cannibalise) were placed in the computer, they could outcompete the Neanderthals through sheer numbers. Eventually they were able to reach the carrying capacity of the simulation, something the cannibalistic Neanderthals couldn’t have done.

In other words, in a harsh environment full of cannibals it’s good to be the best cannibal out there. But when another group enters the picture this in-fighting proves destructive. Thus the Neanderthal extinction could have been self-inflicted.

The problems

This model presents a valid way in which cannibalism could have at first helped the Neanderthals, but ultimately led to their downfall.

But that’s assuming the premises of the model are valid, which they might not be. For example, under this model cannibalism is something done when the environment is pretty rubbish. Yet the cannibalism at Moula-Guercy took place during Marine Isotope Stage (MIS) 5c. This was a relatively warm and bountiful period of European prehistory.

The Krapina cannibalism does appear to have taken place during a cooler, harsher MIS. So it seems like there’s not much correlation between cannibalism and local environment, unlike what the model suggests.

This doesn’t necessarily invalidate this model. It could be the case that cannibalism became common much earlier and these Neanderthals inherited it. Thus they continued to eat each other regardless of the environments. But hopefully it does show that more evidence is needed to validate that the premises of this model are actually true.

For example, the simulation also indicates that cannibalism would have been very common by the end of it. However, cannibalised remains form a small minority of all Neanderthal fossils.

Again, it’s clear more data is needed to test if this model works in the real world. Or at least, worked in the Neanderthal world to help drive them extinct.

tl;dr

A simulation indicates that if environments were tough Neanderthals would have resorted to cannibalism. This would have put them at a disadvantage when modern humans turned up. However, whether this simulation is accurate remains to be seen.

References

Agustí, J. and Rubio-Campillo, X., 2016. Were Neanderthals responsible for their own extinction?.Quaternary International.

Defleur, A., White, T., Valensi, P., Slimak, L. and Crégut-Bonnoure, E., 1999. Neanderthal cannibalism at Moula-Guercy, Ardeche, France.Science, 286(5437), pp.128-131.

Russell, M.D., 1987. Mortuary practices at the Krapina Neandertal site. American Journal of Physical Anthropology, 72(3), pp.381-397.

Saladie, P., Huguet, R., Rodriguez-Hidalgo, A., Caceres, I., Esteban-Nadal, M., Arsuaga, J.L., de Castro, J.M.B. and Carbonell, E., 2012. Intergroup cannibalism in the European Early Pleistocene: The range expansion and imbalance of power hypotheses. Journal of human evolution, 63(5), pp.682-695.

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15 Comments

Peter Kvint · 10th March 2016 at 6:51 pm

1. Neanderthals was humans as was in the past.
2. The number of people was very small. And each group lived on the border of extinction, due to the dry cold unstable climate by the ice age.
3. Most people of the past have become extinct without getting descendants. Only at the end of the last ice age as were all human groups so numerous that they still exist.

Cynthia Echterling · 10th March 2016 at 7:43 pm

In some cultures the dead are eaten out of respect, not killed and eaten. We, at this point, don’t know their motivation. Oh, and there is also ritual defleshing without consumption.

    Adam Benton · 11th March 2016 at 12:21 am

    When dealing with most other prehistoric behaviour its become apparent that there may have been multiple “causes” for it. Cave art is a prime example.

    You raise many good points. Perhaps cannibalism amongst Neanderthals – if it really was that common – had a variety of causes.

Jim Birch · 11th March 2016 at 5:48 am

Cannibalism is a bit of a touchy subject, isn’t it? It seems to me that well-fed people are unable to imagine the impact of extreme hunger.

    Adam Benton · 11th March 2016 at 3:08 pm

    Interestingly, this paper didn’t identify “hunger” as always being the cause of cannibalism. Whilst the temporary boost in resources did help; by far the biggest benefit was the fact you could then occupy their territory and get more out of the environment.

Charles A. Bishop · 11th March 2016 at 8:44 pm

Interesting article! A problem is that there are different types of cannibalism. The most basic is famine cannibalism where out of desperation individuals resort to killing their own kin, especially babies and females. There is also ritual cannibalism as in parts of North America where warriors would take bites from war captives; or they would cook and eat them as among groups in New Guinea. In the case of some Neanderthals it is difficult to distinguish which type was involved. When in Italy some 25 years ago I visited Guattari Cave at Monte Circeo where the skull of a Neanderthal was found in a circle of stones in 1939. The Neanderthal Hotel was later built nearby. The skull has cut marks indicating that flesh was removed. Was this done for ritual purposes or does it represent cannibalism? I suggest the former reason because the cave is (still) filled with cattle bones indicating that there was no shortage of food. The cut marks may have been done after death and were not necessarily the cause of it. Other examples such as Krapina suggest famine cannibalism perhaps where one group killed and devoured another.

harikrv · 13th March 2016 at 1:54 pm

As you say “cannibalised remains form a small minority of all Neanderthal fossils.” I wonder how it can have a direct impact on their extinction? Further if they were successfully killing and eating their own kind what prevented them from killing and eating us also – especially as they were physically superior to us and were also using similar weapons? I wonder if the model took this possibility into consideration! Especially as our flesh would have probably been more tender and tasty compared to theirs! The theory does seem far fetched to me.

    Charles A. Bishop · 13th March 2016 at 4:31 pm

    I agree with Adam Benton. Cannibalism was not common and cannot explain the demise of Neanderthals. In the cases where there is evidence for cannibalism, it is often difficult to tell whether it followed a deliberate murder, or whether it occurred after the natural death of a person. Further, the nature of the fossil evidence makes it difficult to distinguish famine cannibalism from ritual cannibalism, and from cannibalism that occurred following a battle between two groups Also, was cannibalism among Neanderthals more common than among later hunter gatherers in Europe and the Middle East? To my knowledge the question has never been asked. Given the limited fossil evidence in the Upper Paleolithic it would seem to be impossible to answer this.

      Adam Benton · 14th March 2016 at 2:59 pm

      Whilst it may be difficult to differentiate between different types of cannibalism; I think there is enough variety in cannibal sites to indicate that there are different types going on. Even if we can’t pinpoint exactly what those different types are. At some sites for example, the cannibalised remains are buried afterwards but at others they are not. What this means for the underlying motivation is unknown, but it would suggest at least two different motivations. Thus trying to explain all Neanderthal cannibalism with a single model seems a bid simplistic.

    Adam Benton · 14th March 2016 at 2:54 pm

    I think the hypothesis isn’t so much that cannibalism directly led to their extinction, but rather that it weakened them. This made them vulnerable to interspecies competition and it was that which ultimately put them on the path to extinction. Which seems a bit more plausible, but still far fetched like you say.

harikrv · 13th March 2016 at 1:56 pm

Subscribing to comments!

Charles A. Bishop · 14th March 2016 at 4:42 pm

It could have weakened them, especially as the Neanderthal population began to decline. To confirm this, good dates of all the examples of possible cannibalism are needed. If most of them are older than about 50,000 years, then it becomes more difficult to argue that cannibalism weakened them because there was no competition from moderns and animals were relatively abundant. At this time there is insufficient evidence to make a strong case one way or the other.

Leo Rivers · 17th March 2016 at 3:42 am

What would any hominin species experience another hominin as an experience of other? Eating monkeys isn’t cannibalism for humans. Did H Erectus concider H Naledi bushmeat… or ‘sort of an us’? Did the ability to breed identify a closeness as creature to create an instinctual aversion to consumption? A question about an Neanderthal is a question about us all. Or not. Lee Berger, I believe, believes what splitters call species might actually be lumped together… in love.

    Adam Benton · 17th March 2016 at 2:50 pm

    That’s very difficult to say. People have been great at dehumanising members of our own species, so it’s hard to think about how they would have felt towards different species that were still so similar to us.

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