​The moment of Neanderthal extinction is, of course, fundamental to what human evolution meant. The problem is that as important as this moment is, it is so controversial and unclear today. Not only is there no consensus on when this happened, but the reasons for the extinction of this human species are nowhere close to being understood.

In principle, there are three broad categories into which we can include hypotheses regarding the extinction of Neanderthal man. First, it concerns the cognitive superiority of Homo sapiens and the more or less violent extinction of Neanderthals after contact with our species. A species with excellent skills, culture and technique.

The second category is the one that reduces the influence of Homo sapiens to almost zero. Rather, the hypotheses included here take into account climatic or geological factors (see the case of a volcanic supereruption). The last, the version that talks about the assimilation of the Neanderthal population and, implicitly, about its continuity in the form of hybrid individuals. I mean us modern people.

No, I didn’t eat Neanderthals

The truth is hard to determine and most likely lies somewhere in the middle. Returning to the first category, the one about the violent extinction of our evolutionary relatives, which was so often cited a decade or two ago, is rarely mentioned today. No, we didn’t eat Neanderthals and hunt them to extinction.

That’s because there is no evidence, absolutely none, of a massive conflict on a continental scale between the two species. The reality is that there are only two cases, and they are quite controversial, that indicate a possible interaction between the species. The first is the skeleton of a Neanderthal about 50,000 years old, discovered in Iraq, at the Shanidar site. In this case, the skeleton shows an intercostal mark left by a projectile that went ballistic, possibly a spear, a technique associated with anatomically modern humans.

The second example comes from France, from the place of St. Cesaire 1. This case is part of a young Neanderthal skeleton showing a cranial wound caused by a sharp, blade-shaped object. Another technique related to modern human anatomy. As I said, both examples are controversial, but even if they reveal traces of violent interaction between species, this is not enough to conclusively prove continental conflict.

As for the hypothesis of dog domestication, voiced by the American anthropologist Pat Shipman in 2015, it has fallen out of favor. Even if the effect on the efficiency of hunters must have been enormous, even with devastating consequences for other human species, the moment of domestication of dogs came at a time when Neanderthals, according to new dates, were already extinct. As for the spread of pathogens, it is unlikely in highly rarefied populations.

The last item on the list – the cognitive inferiority of Neanderthals – is also no longer relevant. In fact, it is well known that individuals of this species not only had technological advances similar to our species, but even preceded us with certain innovations.

In the light of such arguments, there are only two directions in which hypotheses could be directed: natural factors (climatic or geological) and assimilation. And here a relatively new hypothesis appears, which has been talked about for about 2-3 years. This is Metcalfe’s law and the dimensions of the human community.

Metcalf’s law and the Neanderthal extinction

Metcalf’s Law is not actually a mathematical law. Rather, it is a metaphor, but here it finds its application in an area that few expected. Adopted in the 80s of the last century, the law states that the cost of a communication network is proportional to the square of the number of users connected to the system. More precisely, there are about 190 possible connections among a hypothetical group of 20 people. In a group of 60 people, there are no less than 1,770. And here the problem of the disappearance of Neanderthals arises.

It is a well-known and archaeologically proven fact that Neanderthals lived in small communities. Most likely, they were members of the same family or small groups of families. Sometimes such tribes met in hunting grounds, where a large number of hunters were needed (meetings closely related to the seasonal migration of animals, and ambushes arranged by hunters at certain points on their way). In short, the Neanderthal community had an average of no more than 10-20 members. On the other hand, in the case of Homo sapiens, we are talking about communities that exceed 30 people on average.

And if you think about such a community, then reduce by two-thirds the number of members capable of hunting medium and large animals (we are talking about children and mothers who cared for them, as well as about the sick and wounded). Basically, the Neanderthal community consisted of no more than 6-7 hunters. An option that greatly increased the risk of the group disappearing, especially since the interaction between the various communities was extremely low. What cannot be said about Homo sapiens.

On the other hand, a small group gave a short-term advantage. It has been proven that Neanderthals were strong people who needed at least twice as much calories as Homo sapiens. Thus, food obtained from hunting one or more animals was distributed among a smaller number of individuals. As I said, a short term advantage as it also meant that the geographical area could only support a limited number of Neanderthals. And such individuals, despite the idea of ​​a decade or two ago, rarely migrated long distances.

Last but not least, and here we come to Metcalfe’s Law, it refers to the advantage of more brains. More intelligence will be able to solve more complex problems, find more solutions or diversify community actions. And last, but not least: a larger number of individuals can ensure an increase in genetic diversity. And all of these aspects can be found in Homo sapiens communities, at least those dating back to the Upper Paleolithic.

The difference is not given by individuality

For comparison, remember an anthill! Taken individually, ants are not fantastically intelligent. But when they act as a group, or even more, when they interact between groups, they are able not only to create especially complex colonies, to wage wars, to destroy animals that are hundreds of times their size. The same thing happens with people. The difference is not in individuality, but in how the brains are connected and combined. The more brains, the more efficient the group, implicitly the species.

As I mentioned, Neanderthals never lived in large groups. They only occasionally migrated thousands of kilometers away. Recent analyzes of strontium isotopes in the teeth of Neanderthals from Greece and France show that these people lived in the same area their entire lives. This fact is also confirmed by the origin of the stone material from which they made their weapons and tools. In most cases, it comes from a radius of 5-10-20 kilometers around the camp. It is rarely brought from a distance of 80-100 kilometers. For comparison, at sites associated with Homo sapiens from the Upper Paleolithic and at the beginning of this period, some materials were also brought from a distance of 500-1000 kilometers. And this indicates high mobility.

Interaction between Neanderthal communities, going back to them, was low, as evidenced by low genetic diversity. Probably, migrations took place during periods of climatic fluctuations. And then groups of Neanderthals retreated to their ancestors (Mediterranean, Black Sea, etc.). It is true that many communities disappeared at such times, unable to reach their destination. And in such periods, the number of Neanderthals decreased sharply. The same thing happened with Homo sapiens. They were not superhuman. They were just as vulnerable to the elements.

But the strategy of large groups, the demographic pools from which they could recruit new members when some disappeared, was probably the key to our species’ success.

Well, here is a really clear reason that may explain, not completely, but at least partially, why Neanderthals disappeared (or were assimilated) and Homo sapiens took over.

Bibliography:

• Banks, W., d’Errico, F., Peterson, A.T., Kageyama, N., Shima, A., Sánchez-Goni, M.F., 2008, Neanderthal extinction through competitive exclusion, PLoS ONE, no. 3(12): e3972. doi: 10.1371/journal.pone.0003972.

• Churchill SE, Francis RG, McKean-Peraza HA, Daniel JA, Warren BR, 2009, Shanidar 3 Neanderthal Impaled Rib Wound and Paleolithic Weapons, Journal of Human Evolution, no. . 57 (2), p. 163-178.

• Ovodov N.D., Crockford S.J., Kuzmin Y.V., Higham TFG, Hodgins GWL, van der Plicht J., 2011, 33,000-Year-Old Incipined Dog from the Altai Mountains of Siberia: Evidence of the Earliest Domestication Disrupted the Last Glacial Maximum, PloS ONE, no. 6(7): e22821. doi:10.1371/journal.pone.0022821.

• Shapiro C., Varian HR, 1999, Information Rules, Ed. Harvard Business Press, ISBN 087584863X.

• Shipman, P., 2015, The Invaders: How Humans and Their Dogs Drove the Neanderthals to Extinction, Ed. Belknap Press, Harvard, 288 pp., ISBN 978-0674736764.

• Thiébaut C., Meignen L., Lévêque F., 2009, Les dernières occupations moustériennes de Saint-Césaire (Charente-Maritime, France): diversité des techniques utilizes et comportement

• Trinkaus E., 1983, The Shanidar Neandertals, Ed. Academic Press, London, 528 p., ISBN 1483276473.

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