It is not necessary to divide the genus Homo into species

Nobel laureate: dividing people into different types is a meaningless activity

Julia Tisler, ERR

The Nobel Prize in Physiology and Medicine this year was awarded to a geneticist with Estonian-Swedish roots, one of the founders of paleogenetics Svante Peabo. He developed a method for reconstructing the genome from scraps of DNA and used it to read the genomes of the Neanderthal, Denisov man and many other ancient people.

Paabo and his colleagues proved for the first time that it is possible to isolate DNA or hereditary material even from human bones that are thousands of years old. In 1985, he managed to obtain the DNA of a 2,400-year-old Egyptian mummy.

In 2002, Peabo attracted a lot of attention when he announced the discovery of the "speech gene" — FOXP2, which is missing or damaged in people with speech disorders. In the following decades, Peabo succeeded in sequencing the complete genome of the Neanderthal, a now extinct human-related species. The scientist also found a new human species — Denisovans, who at one time lived with Neanderthals and humans and mixed with them.

In recent years, Peabo has investigated, among other things, the possibility of isolating ancient DNA from sediments, and the influence of Neanderthal gene variants on brain development. The latter may help to understand why modern humans survived and Neanderthals became extinct.

In 2019, Peabo was elected a foreign member of the Estonian Academy of Sciences. In the same year, the Novaator portal published an interview with the scientist.

"Culture is much more important than genes when it comes to people's self-determination and their history. Dividing people into different species is a meaningless academic exercise," says Svante Peabo, the founder of paleogenetics.

— Why are we still so concerned about the question of where we came from?

— It's really interesting. Many have been studying their genealogy for the past few hundred years. In the same vein, the research of where all the people living on the planet today come from. It is here that Neanderthals and Denisovans, our closest relatives, come on the scene. If we want to understand what is characteristic of a person in a phylogenetic sense, we must compare ourselves with him.

— But still, should we spend time and effort trying to find a specific valley or swampy place where the common ancestor of all people lived?

— I don't think we can find a specific point. It is quite obvious that the ancestors of people living today came from Africa. They acquired their modern appearance 300,000-200,000 years ago. However, it is unclear exactly where this happened. Probably, the territories were very extensive. Then these modern humans began migrating from Africa, more massively just 100,000 years ago, meeting, for example, Neanderthals in Europe.

Neanderthals eventually died out naturally, but before that they mixed with modern humans. If your genetic roots are outside Africa, for example, in Europe or Estonia, about two percent of your DNA comes from Neanderthals. If you like, you can say that we have a Neanderthal component. 

Although I haven't seen the most recent textbooks, you must have made life much more difficult for children. Biologists have had problems defining species in the past, but your findings seem to indicate that the word "species" is outdated, at least when dividing the genus Homo into groups.

Yes! The notion of a species as such is an academic construct. We know that in nature groups gradually diverge. But then quite often they get together again and mix. It makes no sense to me to discuss whether Neanderthals were a different species from modern humans or not.

It is known that we mixed. We could have shared descendants. And those, in turn, also had their descendants. If you want to call them a different species because they looked and behaved a little differently from us, that's up to you. I have nothing against it.

— In that case, what characteristics can we use to divide people into different groups? To this end, sorting into different groups based on phylogenetic analysis — the shape of bones or DNA — is somewhat similar to using the Schrodinger equation in physics. We know that it works, but if you don't delve into the result, then something is slipping away.

— Beauty is in the eyes of the beholder. It depends on what scale we are talking about and what characteristics we consider important. Nowadays, people mostly define themselves by the language they speak. Culture is very important. Through it, we define ourselves, including our native language.

Of course, there is also a genetic history. We all have a better understanding of where our genes were in the past, but I would even say that they are not very important for our history. I often tell students how I feel about my roots when I visit the Acropolis in Greece. Our democracy, most of our culture and architecture come from there. However, I know for sure that my genes have never been to Greece.

— In light of recent archaeological finds, it increasingly seems that we cannot use culture to distinguish Neanderthals from our ancestors.

— The more we learn about Neanderthals through archaeology, the more we understand that they were also involved in things previously considered characteristic of modern humans, such as the creation of certain art forms.

But I still think there is something special about modern people. All other early human forms — Denisovans, Neanderthals, other people who lived in Indonesia, Asia and parts of Africa — existed much longer than modern humans. Despite this, they did not do many things that are characteristic of us. They did not cross reservoirs, the other shore of which was not visible. Their population probably never exceeded 100,000.

Compared to them, our technology and culture have changed very quickly. For example, when we compare tools made by Neanderthals in Western Europe and Central Africa, we see that they look the same for hundreds of thousands of years.

On the other hand, in the case of modern people, it is very quickly possible to understand which of them came from Asia, Europe, etc. Their numbers also increased rapidly, and they began to spread across Europe and the world. They did it in 50,000-60,000 years. Today we already influence most of the biosphere.

There is still something special about modern people. But what exactly? This could become a million-dollar question that will probably take at least the next decade to answer.

— Another important area in which you are collaborating with Dr. Vivian Elephant concerns the sequencing of DNA found in the environment.

It is very interesting that we can use extremely sensitive methods to isolate DNA from sediments. During archaeological excavations, we often find stone tools, traces of human habitation, but not bones. In this case, we don't even know what kind of group of people it was.

Now it is possible to obtain genetic material from the sediments and tell whether it was a Denisovan, a Neanderthal or a modern man. I hope we can elaborate on this in more detail. Therefore, I think that this method will become a standard tool in archaeology.

— Speculation is a thankless occupation, but can we find additional unknown groups of people in the process?

— I would not discount the possibility of the existence of other groups of people who lived between 50,000 and 40,000 years ago. We know, for example, that dwarf people lived in Indonesia at that time. We have tried to isolate their DNA, but so far to no avail. They probably separated from other people before the appearance of Neanderthals. We know about them and other groups that lived in Africa on the basis of archaeological finds. Therefore, in the future, we will learn more about them.

— I often think about what would happen to our current society if we met today a group of people whose intelligence would be at least comparable to ours.

A lot of fiction has been published on this topic, for example, about the discovery of Neanderthals in some remote valley or mountain. I would wait until it actually happens.

Of course, it's interesting to think about what we would do with them. Would they show even more racism than to other groups of people living today? Or will it help to erase the clear line that we now draw between animals and people?

Neanderthals had tools, they communicated with each other in a certain way, but they were different from us. Perhaps this would make us more receptive to the idea that there is no absolute difference between humans and animals, there is a continuous scale. Who knows how the chain of these events will develop further?

— And finally, how has paleogenetics changed our ideas about ourselves as people? The idea of genetic purity at any level seems to have become meaningless.

— From the point of view of human evolution, it became obvious that extinct human groups bequeathed their genetic material to people living today. We mixed not only with each other, but also with all other forms. From other works it also became clear that people migrated, for example, to Europe during the Stone, Bronze and Iron Ages much more actively than previously thought.

These groups were strongly mixed and replaced each other on a larger scale than we thought 10-20 years ago. It shows that our story was very interesting and we were often on the move.

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