Neanderthals did not disappear because modern humans were the smartest or the best. There were simply more of us. We can express several unexpected thoughts about the explanations that existed until recently of why our closest relatives, the Neanderthals, disappeared, and we modern humans remained.
For decades, scientists have put forward tempting explanations about modern man as a hitherto unseen creative and technologically outstanding natural force that originated in Africa and spread throughout the planet, displacing all previously existing types of people. But now, new research shows that the mystical disappearance of the Neanderthals can be explained by a much more commonplace cause. Their fate was sealed because in Africa there was a larger community of modern people who slowly penetrated Europe over many millennia.
“It now boils down to asking ourselves what happened before we came up with simple explanations like climate change, a better mind, an advanced culture or a varied diet. We can show that, all other things being equal, one would expect Neanderthals to die out anyway, regardless of all these factors. This, of course, does not mean that these factors did not exist, but we still expected what actually happened,”says Oren Kolodny, a researcher at Stanford University in the US, the author of the new study.
An article about this research was recently published in the scientific journal Nature Communications.
This study is a breath of "pleasant fresh air"
Peter Kjergård, Director and Professor of Evolutionary History at the State Museum of Science and History, is enthusiastic about a new look at one of the great and classic issues in the history of human development.
“We get a breath of pleasant fresh air using the well-known evolutionary models of hominids (individuals to which the human lineage belongs, ed.). In my opinion, there was too much conservatism and disgust in the study of human evolution. We attached too much importance to the widespread idea of praising the unique properties of man, who, however, was completely unreasonably assessed differently from all other animals,”says Kjergaard, who himself was not involved in the study.
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Mathematical model may explain the disappearance of Neanderthals
Self-praise is based on the fact that we humans have imagined over time that we are something special. Therefore, we clung to finds that could be interpreted as if our ancestors were smarter, and we said about Neanderthals that they were stupid, lazy and primitive. Instead of all this, we had to work soberly and impartially in the way scientists are trying to do it today.
By using a mathematical model that compares Neanderthals to modern humans and simply looks at differences in population size and migration patterns, scientists can explain distribution patterns that are consistent with archeology.
The replacement by Neanderthals can be explained by the fact that separate small groups of modern people, and not a powerful wave, came to Europe from Africa for thousands of years. Most of them died, some, apparently, were lucky enough to settle in Europe, several generations of them died out and were again replaced by Neanderthals.
But if small groups appeared again and again over the millennia, then, as the model shows, some of these people inevitably settled, spread and increased in number so much that, in the end, there were no Neanderthals left.
So this simple model could explain the disappearance of the Neanderthals.
“It used to be thought of as a quality issue, but now it is explored as a quantity issue and is shown using several realistic scenarios that it can now be done. This is really good, because with new data in the future it will be possible to verify some things, for example that there was a small group of modern people outside of Africa for a long time,”says Mikkel Heide Schierup, professor at the Center for Bioinformatics at Aarhus University …
Evolution is not necessarily due to selection
This research by scientists leads to the idea that the idea of our special good biological traits disappears, instead of it there is a statement that our whole existence is reduced to a question of chance. However, all this is not as unexpected as it might seem.
“Since the 70s of the last century, there has been a so-called neutral model of evolution, showing that many results of evolution should not be explained at all by selection, which many, however, perceive as the existing main source of changes in the biological world. The article leads to the realization that we need several clear hypotheses, both to explain the interaction between Neanderthals and Homo sapiens, and to explain the disappearance of Neanderthals. We can model these hypotheses and then use, for example, archeology and new DNA research to test them,”says Felix Riede, professor of prehistoric biology at Aarhus University.
One will die out or two will adapt
The idea of a new study appeared two years ago, when Oren Kolodnya, during an interesting lecture, had an idea about how to actually solve the question of the mysterious disappearance of Neanderthals.
“I realized that first you need to have a zero model that describes what you want to get when these two meet. If these were only two species of animals that usually occupy the same ecological niche, then what should have happened when they were in the same area? - says Oren Kolodny.
The answer is well known: they will compete for the same resources and then one species will become extinct. Or they will conclude an evolutionary "deal" where each species will specialize in its part of the ecological niche in order to thus divide this area among themselves.
In the case of Neanderthals and modern humans, the answer was pretty clear for Kolodnya: both species lived using the same wide range of resources, lived in the same dwellings, created the same stone tools, etc.
Oren Kolodny was very doubtful that Neanderthals and modern humans would share a niche. And since the populations of both species were relatively small, it would be difficult to imagine how they were supposed to produce offspring sufficient for each to evolutionarily specialize in its part of the biocenosis.
“I assumed as a starting point that one of the species would become extinct. The only question was which one,”says Oren Kolodny.
Neanderthals were expected to die out
The answer can be found in population size and migration between Africa and Europe. There were more people in Africa than there were Neanderthals in Europe, since conditions in Africa made it possible for more individuals to live. Therefore, the African species (modern people), on average, went more from Africa to Europe, where the Neanderthals lived, and not vice versa.
Most researchers today agree that modern people in the last 120 thousand years moved from Africa to the Middle East and, perhaps, further to Europe. This was not a large migration of thousands of fruit hunters and gatherers, but small groups of less than 50 individuals. And, perhaps, such a process occurred so rarely that the resettlement of various groups was separated by a period of 100 years or more.
If it was such a calm and quiet flow of people, all the time creating migration pressure on Europe, then the result is clear - “the death of the Neanderthals was absolutely the way I imagined it,” says Kolodny.
The important question, Kolodny said, is whether the extinction of the Neanderthals, from a realistic point of view, could have occurred in the period that the researchers envisioned.
Developed mathematical model
The thought of conducting an experiment turned into a mathematical model that clearly showed that the two species split into two groups, respectively, in Europe and Africa, and that migration took place between the two continents.
The model has a restrictive function designed for a certain number of groups, so when one group accidentally dies out, it is replaced in the model by a new group, which can be either modern humans or Neanderthals.
Together with mathematician, Stanford University professor Marcus Feldman, Kolodney tested a lot of different parameters in the model (for example, population sizes, where groups quickly replace each other, etc.) and in almost all "acceptable" parameter assumptions the result shows that the replacement of Neanderthals by modern humans occurs in accordance with a period of about 12,000 years. It is this period that actually corresponds to archaeological finds (39-51,000 years ago).
Model settles scores with our ego
The researchers also tested more complex (real-world) models. And each time the results fell within a realistic time frame in such a way that the replacement of Neanderthals could be explained by differences in population size and resettlement patterns. Therefore, the usual explanations about the special properties of modern people or the worst properties of Neanderthals disappear.
“There is a deep conviction that we are here because we were the smartest and we had some good qualities. But it's good that the model refutes all this and shows that a reason is not always needed, it may well be just a play of chances. The differences that we find between modern humans and Neanderthals may also be correct, such as the fact that we traded more (than Neanderthals, ed.), But it cannot be argued that this is why we are here now,”says Mikkel Schirup (Mikkel H. Schierup).
The driving force was not culture, but quantity
Feldman and Kolodny point out that the observations and arguments that have existed so far, confirming that modern man, who came from Africa, had new and better qualities, are untenable.
It turns out that those found improved stone tools and objects of art that are used for such arguments, in many places appear only 10-20 thousand years after the first modern people arrived there.
“So we believe that the driving force behind the replacement was not an advanced culture. Culture, on the other hand, was a product. The cultural changes were caused by the interaction between the two species with adaptation to the new biocenosis,”explains Oren Kolodny.
Research opens the door to great progress
“This study is especially interesting because it disproves the theory that Neanderthals became extinct, as Homo sapiens had advantages over them. Of course, there is no reason to believe that development has followed this model step by step all the time, but it equips us with an excellent analytical tool to look at both already known material and new recently emerging. This gives us a good starting point to test other scenarios and evaluate new and old finds,”says Peter Kjergaard.
Oren Kolodny primarily views this study as an example of how various experts can lead us forward and give us more knowledge about human evolution.
“This is such interconnected research in various fields that opens up new horizons for us and that I believe will give us answers in the future,” says Kolodny.
The same is said by Peter Kjergaard: “The time has come to get results in this area, and we are seriously using all interconnected branches of science with all their resources. I foresee great progress in the coming years."
Rasmus Kragh Jakobsen