Who is the "Denisovsky man"? Ancient man from Denisova cave, who is he? A new kind of man in Altai

In the January issue of the journal Nature, two articles were published at once on the habitat primitive man on the territory of Southern Siberia - in the famous Denisova cave. The researchers specified the dates: when and by whom the cave was inhabited. And if about Neanderthals and people modern type(Homo sapiens) we remember something from school, then who are the Denisovans?

A copy of a Denisovan's tooth. Photo: commons.wikimedia.org

Denisova cave is located in the south Altai Territory. Archaeological work has been carried out there since 1982. During the excavations, 22 cultural layers with human remains, associated artifacts and animal bones were discovered. The most significant discoveries awaited archaeologists in the 11th layer aged 50 thousand years - finds were made in it that glorified Denisova Cave to the whole world. These are three molars, a phalanx of the little finger, bone tools and women's jewelry.

Deciphering the DNA of the bones made a sensation and in the top list of scientific breakthroughs in 2012, according to Science magazine, took second place (after the discovery of the Higgs boson). It turned out that the remains belong to a species of people previously unknown to science. Prior to this, it was believed that only two types of people inhabited Eurasia - the Neanderthals and the Cro-Magnons who came after them (the ancestors of Homo sapiens). Genetic analysis showed that the new species (it was called the Denisovan man) is close to the Neanderthals, but nevertheless diverged from them along different branches of evolution about 640 thousand years ago.

After the discovery of geneticists, all objects and artifacts found in the cave were carefully and repeatedly examined. Dozens of scientific works in world laboratories of the world. The phalanx of the little finger, as it turned out, belonged to a girl aged 7-12 years. Partially recreated her appearance: she was dark-skinned and brown-eyed.

Denisova cave. Photo: RIA Novosti / Alexander Kryazhev

Scientists have not been able to detect the genes of the Denisovan man in modern inhabitants of Eurasia (unlike the genes of Neanderthals, we can have up to 4% of them). The only people living on Earth who is somehow genetically related to this mysterious population lives on the islands of Melanesia, which is northeast of Australia. Its representatives found 5% of common genes with the read genome of Denisovans.

It has been established that for more than 200 thousand years Denisova Cave was home to three types of people. They lived there throughout the Paleolithic era, which ended 12 thousand years ago. And the Denisovan people lived in it 50 thousand years ago.

“Over the years of work in the Denisova Cave, we have received a number of clear evidence that it is on this territory that the Denisovans own the formation of the Upper Paleolithic culture, which is usually associated throughout the world with the spread of Homo sapiens,” says Director of the Institute of Archeology and Ethnography SB RAS Mikhail Shunkov. “And the oldest Denisovan bone fragment to date was found in the lowest layer of the Denisova Cave, which is over 300,000 years old!”

Remember we discussed the issue. Let's continue our study of this topic.

The Altai Mountains are located in such a way that it was simply impossible for numerous migrations of various bipedal creatures to go around them. Nearby is a vast strip of steppes, running from the Yenisei to the Carpathians, which served as a real "gates of the peoples" (usually that was the name of that part of it that passed between the Ural Mountains and the Caspian Sea). On the other side of the mountains are deserts, opening the way to the Far East and Southeast Asia. Altai contains many interesting and mysterious places, among which the famous Denisova cave with a large grotto - it is always dry in it, and the hole under the dome gives light during the day and serves as a natural chimney.

And here's what was found...

Not surprisingly, Denisova Cave has harbored members of the genus Homo for hundreds of thousands of years, starting with the Neanderthals who settled there 280,000 years ago. Left there traces and people historical era- Turks and Huns, creators of vast nomadic empires. Throughout this gigantic period of time, people lived here, made tools, ate or butchered hunting animals - bones of a yak, donkey, rhinoceros, hyena were found in Denisova Cave.

Thus, over the natural floor of the cave, two dozen cultural layers filled with artifacts have grown - evidence of the life of various inhabitants. To explore these cultural layers (and excavations began here in the second half of the 1970s), archaeologists had to dig a deep hole. And in 2008, a famous discovery happened: in Denisova Cave, among a huge array of cultural layers, a tiny bone was found - as it turned out later, the phalanx of the little finger of a young female. We can talk about great scientific luck, since this find, plus a few more small bone fragments (two teeth, possibly a phalanx of a toe) became the only evidence of the existence of a hitherto unknown species of people on Earth.

20 cultural layers have grown on the floor of the Denisova Cave. The discovery of small bone remains of Denisovans in this massif is a great success.

Surprises continued in 2012, when the work of a group of scientists from the Max Planck Institute in Leipzig was published (the team leader was the Swedish biologist Svante Peebo). Scientists managed to sequence both nuclear and mitochondrial DNA of Denisovans with high accuracy, as our extinct cousins are now called, and it became possible to objectively talk about the relationship of people who lived in Denisova Cave 75-30 thousand years ago with Homo sapiens and Homo neanderthalensis. The sequencing of "Denisov" DNA became real only with the advent of new technologies for working with genetic material, which, as a rule, is fragmentary in fossil bones. In particular, the method of artificial restoration of double-stranded DNA was used in cases where one of the strands in the original sample turned out to be damaged.

The diagram shows the family tree of sapiens, Denisovans and Neanderthals, as well as great apes, coming from a common ancestor. Red shows the threshold after which out of 24 pairs of simian chromosomes after the fusion, 23 pairs of human chromosomes were obtained.

As for kinship, it was possible to find out that, according to the analysis of mtDNA, the difference between modern man and Denisovan is 385 nucleotides, while the difference between Homo sapiens and Neanderthal is 202 nucleotides. Nuclear DNA analysis has shown that Neanderthals and Denisovans had a common ancestor who lived perhaps about 700,000 years ago (dating is extremely approximate). The ancestor of this branch and Homo sapiens - the so-called "preceding man" (Homo antecessor) lived on Earth more than a million years ago.

So, everything is clear with kinship? Not really. It is known that Homo sapiens appeared about 200,000 years ago on the African continent. One and a half hundred thousand years later, a small population of sapiens (about 40-50 thousand people) decided to leave their African home and went to the Middle East, and the descendants of these people settled on all continents except Antarctica. Thus, all the original inhabitants of the Old and New Worlds, with the exception of Africa - that is, white Europeans, Chinese, Eskimos, American Indians - are descendants of fugitives from Africa, whose number is comparable to the population of the regional center. At the same time, sapiens were, of course, not the first representatives of the genus Homo who left for Eurasia. Prior to that, Homo erectus traveled there, giving offspring in Europe in the form of Heidelberg man or in Asia in the form of Sinanthropus and Pithecanthropus.

Arriving in the Middle East, sapiens met there earlier Neanderthals. Then what happened in science is called hybridization: our ancestors and Neanderthals began to interbreed, and they had offspring. Presumably this was the first, but not the only wave of hybridization of these species. The second episode, according to genetic data, could occur on Far East with the participation of Homo sapiens ancestors of the Chinese and American Indians. To date, the percentage of Neanderthal genes in the genome of representatives of different peoples of the world is 1-4%.

After it was possible to obtain accurate data on the Denisovan genome, another important discovery was made. It turned out that Denisovans could not avoid hybridization with Homo sapiens either. Living not far from the "gates of the peoples", they met with a certain branch of the ancestors modern people, which then proceeded towards Southeast Asia, or rather, its island part. Melanesians, representatives of the Australoid race (among them the most famous among us are the Papuans) contain in their genome up to 6% of the "Denis" genes. Although it is not at all necessary that hybridization occurred in Altai, it is now believed that this type of people had a wide habitat in Eurasia.

Thus, some modern people, living, however, mainly in one corner of the planet, may consider themselves closer relatives to the Denisovans than everyone else. However, there is another mystery that was presented by the find in Denisova Cave. It seems that on its basis it is possible to assume the existence of another type of people from whom even a tiny bone has not yet been found.

Neanderthals and Denisovans form two branches descended from a common ancestor, but, as already mentioned, Homo neanderthalensis is genetically noticeably closer to sapiens than Denisovan. Moreover, in the Denisovan genome there are approximately 1% of genes that Neanderthals do not have and which are noticeably older than the rest: the American biologist David Reich from the Harvard Medical School drew attention to this. It remains to be assumed that hybridization with sapiens was not the only one that the "Denisov" people underwent. Now it is suggested that they could interbreed with other species of the genus Homo along their historical path.

The researchers drew attention to the fact that the tooth found in Denisova Cave, which, like a fragment of the phalanx, became the subject of genetic analysis, has an unusually large size, which is typical of earlier hominids. This may mean that representatives of some kind of people who left Africa even earlier than sapiens, and Denisovans, and Neanderthals acted as partners in crossing. Perhaps nothing is known about this species so far, but it can be assumed that they were, for example, representatives of the Heidelberg man. What's stopping you from checking it? The absence of a sequenced genome of the latter.

We will have to remind again that the isolation of high-quality genetic information from the fossil remains of Denisovans was a unique case and a great scientific success. The same goes for Neanderthal genes. The fact is that both of them lived in relatively cold and humid areas of the world, and the climate ensured the safety of complex molecules inside the bone remains. In a hot climate, where the sun burned the bones white, DNA was almost completely destroyed.

Discoveries are yet to come

Unfortunately, due to the paucity of the fossil material found so far, it is very difficult to say how Denisovans differed from modern people. appearance and behavior, or whether they possessed, for example, speech. Differences in the Sapiens and Denisovan genomes may indicate that certain mutations that are responsible for important developmental functions in our genome nervous system and the work of the brain, the Denisovans, as representatives of another branch of humanity, are not marked. This may mean that these extinct people did not possess a human mind in the full sense, which, of course, did not prevent them from leaving offspring together with sapiens.

It would seem that Homo florensiensis also fits into the same series of “cryptohumans” - the remains of representatives of this species were discovered in 2003 in the Liang Bua cave on the island of Flores. These creatures, who were immediately dubbed "hobbits", were distinguished by small stature (1 m) and an extremely small brain volume - 400 cm3. This is smaller than that of a chimpanzee and is comparable to the brain volume of an Afar Australopithecus, which did not belong to the genus Homo. Thus, the Floresian dwarfs were obviously at a lower stage of development than the Neanderthals or Denisovans. Yes, they produced primitive stone tools, probably engaged in hunting and construction with their help, but Australopithecus was also capable of creating stone tools. According to one of the existing hypotheses, Homo florensiensis could be a descendant of Pithecanthropus, a fairly developed creature that fell into the conditions of island isolation (and the modern and fossil fauna of the island of Flores is filled with evolutionary curiosities) and changed there, or, one might say, degraded. The latter term, however, is hardly appropriate, since it implies an understanding of evolution as an unchanging movement from lower forms to higher ones, while in reality only adaptation by natural selection matters. Now, however, far from everyone shares the hypothesis of a reduced and dumber Pithecanthropus, suspecting some less developed creatures such as the same Australopithecus in the ancestors of the "hobbits".

However, there is another interesting example, when traces of some mysterious humanoid creature are clearly traced in the genome of modern man. True, we are again talking about a specific group of Homo sapiens.

Africa is a real treasure trove of genetic diversity. If we remember that non-African humanity goes back to several tens of thousands of Africans who went to Eurasia, it is not difficult to assume that the genetic differences between a German and a Japanese may turn out to be much smaller than between representatives of different African peoples where sapiens evolved for 200,000 years. But the Pygmies in western Cameroon and the Hadza and Sandawe peoples in Tanzania are a special case. As can be seen from geographical map, Tanzania and Cameroon are separated by a decent distance, but the representatives of the three peoples mentioned are united by common sections of DNA, and this indicates, firstly, common ancestors who lived at the latest 40,000 years ago, and, secondly, that these the very ancestors were already owners of the aforementioned plots. A group of biologists from University of Pennsylvania under the guidance of Sarah Tishkoff, published a paper in the journal Cell, in which it was argued that the DNA sections common to the three peoples are traces of hybridization with a hitherto unknown species of people who lived in Africa 80-20 thousand years ago, which descended from a common ancestor with Neanderthals about 1.2 million years ago.

The only problem is that from these hypothetical people, again, not a single bone was found - geneticists again made a discovery "on the tip of a pen." Indirect confirmation that even in the recent era in Africa there could be some types of people who are not related to sapiens, can serve as a find in Iwo-Eleru (Nigeria). A rather primitive skull was discovered there, however, dating from the era of the sapiens' reign of 13,000 years ago. In other words, there is a problem of a certain mismatch between the calculations of geneticists and the findings of paleoanthropologists working "in the field."

But let's not forget: if there was no luck with the discovery of tiny bone fragments in the Denisova Cave, today no one would know about any Denisovans at all.

Australians were the first

The map on the next page shows the migration routes of the ancestors of different groups of Homo sapiens across Eurasia. As you can see, the ancestors of the Australian Aborigines and the Papuans were in the same group of Africans as the ancestors of the future population of Europe and Asia - they together separated from their African relatives 75-62 thousand years ago. However, the “Australian” branch (red arrow) went to Eurasia first, even before the “Europeans” separated from the “Asians” 38-25 thousand years ago (in particular, the ancestral line of the Chinese, the Han, is meant). The second wave of migration, which passed through Western Asia, India and Indochina, displaced and absorbed the representatives of the "Australian" branch on the continent, and the natives of Australia and the Papuans were isolated for 50,000 years. The map also shows hybridization with Denisovans.

genetic clarity

The honor of scientific evidence of hybridization between Homo sapiens on the one hand and Denisovans and Neanderthals on the other belongs to a group of scientists from the Max Planck Institute for Evolutionary Anthropology in Leipzig (Germany) led by the Swedish geneticist Svante Peebo. Based on bone remains from Croatia, researchers were able to read the Neanderthal genome in 2010. In 2012 similar work was carried out in relation to the genome of Denisovans. The "Denisovsky" genome was sequenced with an average coverage of 31 (99.4% of nucleotides were read at least 10 times, 92.9% - at least 20). Thus, the quality of the genome reading corresponds to the sequenced genomes of modern humans, which made it possible to make comparisons.

Here's some more interesting information.

An unusual variant of the gene involved in the body's production of hemoglobin is widespread among Tibetans. This feature allows them to live in the mountains at an altitude of more than 4500 meters above sea level. Published in the journal Nature, a study shows that this gene was inherited by the Tibetans from the Denisovan man, a species (or subspecies) of the genus related to modern humans and Neanderthals. Homo. The Denisov people, who died out 40-50 thousand years ago, are known from bone remains found in the Denisova Cave in Altai.

"We have very clear evidence that this version of the gene comes from Denisovans," said Rasmus Nielsen, a professor at the University of California at Berkeley, who led the study. “This shows that humans have evolved and adapted to new environments by getting genes from other species.”

A gene known as EPAS1 is activated when oxygen levels in the blood decrease, increasing the production of red blood cells. This helps a person cope with peak loads. EPAS1 is even called the “superathlete” gene, as some variants can help athletes quickly increase their hemoglobin levels, increasing endurance. In the highlands, the usual version of the work of this gene is fatal. An increase in the number of red blood cells in the blood leads there to hypertension and heart attacks, as well as to the birth of children with lower birth weight and an increase in infant mortality. The gene variant found in Tibetans avoids these side effects because it is less active.

In 2010, studies also conducted by Rasus Nielsen and his team showed that when the ancestors of the current Tibetans settled in the Tibetan Plateau, more than 2.75 thousand years ago, their numbers dropped sharply, and then began to grow thanks to that part of the population that had genetic features that make life in the mountains easier, including a special variant of the EPAS1 gene.

“We found that part of the EPAS1 gene in Tibetans is almost identical to the Denisovan gene and is very different from all other people,” Nielsen says. Nuclear DNA extracted from a Denisovan finger bone was compared with Chinese and Tibetan genetic material provided by the Max Planck Institute for Evolutionary Anthropology. Nielsen suggests that modern humans, having left Africa, interbred in Eurasia with Denisovans. Their descendants subsequently settled China and Tibet

sources
The article "Cryptohumanity" was published in the journal Popular Mechanics (No. 141, July 2014).
http://www.popmech.ru/science/17225-denisovskiy-chelovek/#full
http://elementy.ru/lib/431435
http://paranormal-news.ru/news/denisovskij_chelovek_skreshhivalsja_s_neizvestnym_nauke_vidom_cheloveka/2013-11-21-8087
http://polit.ru/news/2014/07/03/ps_epas1/

Here is some more information for you

In the genome of an extinct species - Denisovans - unusual pieces of DNA were found, which, apparently, got it from some other group.

Perhaps this is evidence of the existence of a completely different species of hominins, still unknown to science. Or it could be the first genetic evidence for one of the many species that we only know about from fossils.

The new hominin left its mark on the Denisovan genome, an extinct hominin whose existence is known from a finger bone and two teeth found in a Siberian cave. No one knows what the Denisovans looked like, since we have no other fossils at our disposal. However, geneticists managed to decipher their genome with high accuracy.

David Reich from Harvard Medical School (USA) carefully studied the Denisovan genome and came to the conclusion that some segments do not fit into the overall picture.

The genome says that the Denisovans were cousins Neanderthals - but this has long been known. Their line split from ours about 400,000 years ago before splitting into Neanderthals and Denisovans.

This should mean that Denisovans and Neanderthals were equally different from modern humans, but upon closer inspection, Mr. Reich found that this was not the case. "The Denisovans appear to be further from modern humans than the Neanderthals," he says. For example, scattered fragments, which account for up to 1% of the Denisovan genome, look older than the rest.

This is best explained by the fact that the Denisovans interbred with some other species. Or something happened that Mr. Reich himself says: “Denisovites saved hereditary information unknown archaic population unrelated to Neanderthals."

Johannes Krause from the University of Tübingen (Germany) considers the data presented convincing, "it is difficult to ignore them." Mr. Krause is one of those geneticists who study the Denisovan genome in search of traces of interbreeding. The fact is that the teeth of the Denisovans are unusually large, as if we have a more primitive species in front of us. If the Denisovans did interbreed with an archaic species, that might explain everything.

So, what kind of people were these with whom the Denisovans intermarried? Mr. Krause is betting on a species we already know, because many hominins are known only from fossils and have never been genetically analyzed. And many of them could meet Denisovans on their way.

The most likely candidate is Heidelberg man, says Chris Stringer of the Natural History Museum in London (UK). This species existed 250–600 thousand years ago. It originated in Africa, but then spread throughout Europe and western Asia. The early Denisovans, whose ancestors followed the same path, might have come into contact with them.

Another option is Homo erectus. He was even more widespread than the Heidelberg man: he even reached Java. But its western populations - occupying the same territory as the Denisovans - could not wait for them.

DNA analysis of the Heidelberg man could clarify the situation, but this is easier said than done. The genome of Denisovans and Neanderthals survived primarily because they lived in cold and dry places. Other hominins preferred hot, humid areas where DNA quickly decays. In Asia, a number of fossils have been found, the species identity of which cannot be determined, and scientists have so far unsuccessfully struggled to isolate DNA samples from them.

Whoever that mysterious people turned out to be, the main thing is to understand that interspecific crossing was a completely common thing in the history of human evolution. After our direct predecessors went beyond Africa, they “slept” with both Neanderthals and Denisovans. And although the ancestors of today's African hunter-gatherers never left the continent, recent research has shown that they did not disdain unidentified hominins. Apparently, this episode took place approximately 35 thousand years ago, and they were interested in representatives of a species that separated from our lineage about 700 thousand years ago.

The results of the study were presented in London at a discussion meeting of the Royal Society on ancient DNA.

The nature of man, the origin of man - this is what excites people from the most ancient times. There are many versions, theories. Scientists are conducting research, trying to find answers to all questions. After reading the article, you will learn about another subspecies of ancient extinct people.

The Denisov man, or Denisovan, presumably existed in the Soloneshensky district of the Altai Territory, not far from the Denisova cave. Evidence of this was found in different periods and in different layers of the cave.

On the this moment only five fragments were found that allow us to talk about the Denisov man. However, these traces are still not enough to restore its appearance completely. However, the fragments found are enough to argue that the remains of this person are different from the remains of Homo sapiens, as well as from the remains of a Neanderthal.

Denisova cave

This cave is the most popular archaeological monument that Altai can boast of. Denisov man lived here, 250 kilometers from the city of Biysk. The cave is quite large, with an area of 270 m².

It is located near settlements, belongs to the horizontal type, which attracts a large number of tourists. However, there are also archaeologists here, whose hard work nevertheless led to a result.

According to the results of research, in the lower layers of the cave, whose age is about 120 thousand years, stone tools and jewelry were found, as well as traces of an ancient man, who was called Denisov.

Fragments of the remains of the Denisovan man

During the existence of the Soviet state, three molars were found in size much larger than the teeth of Homo sapiens. According to the examination, they belonged to a young male. A fragment of a finger phalanx was also found, the analysis of this element is still being carried out.

In a later period, already in 2008, another element was found - the bone of the phalanx of the child's finger.

Denisovan genome

The found fragment in the form of a Denisovan finger phalanx was studied by a team of scientists from the Leipzig Institute for Evolutionary Anthropology. The study showed that the mitochondrial DNA of Denisovans differs from the mitochondrial DNA of Homo sapiens by 385 nucleotides. It is worth noting that the Neanderthal genome differs from the Homo Sapiens genome in 202 nucleotides.

Denisov man is closer to Neanderthal than to Homo sapiens. It is also worth noting that his genes were found in the Melanesians, and this allows us to talk about the massive interbreeding of people at the moment when the Melanesians left Africa and migrated to the southeast.

Descendants of Denisovan man

According to the research, denisovan man separated as a subspecies about 400-800 thousand years ago. Today, the study of the fragments found in it allows us to find its genes in many modern nations. For example, most similar elements are found among the inhabitants of the countries of Southeast Asia and southern China, despite the fact that traces of these ancient people were found in Siberia.

It was also found that the named subspecies of extinct people, as well as the Neanderthal, transmitted European population genes responsible for the immune system. Thanks to this discovery, it was also possible to make computer model, demonstrating the migration path of different types of ancestors of modern people and the places of their meetings with the Denisovans.

Scientists from Sweden believe that it is possible to find traces of the Denisovan man by comparing the found DNA with the DNA of modern people.

After the comparison, information was received about the similarity of the Denisovan with modern man, and about matches found in Neanderthals and Denisovans. It was also possible to find out that the Denisovan genes are contained in the genotypes of people belonging to the oceanic and non-African populations.

Work at Harvard Medical School

According to research at Harvard Medical School, Denisovans are much further from modern humans than Neanderthals, although they were originally considered cousins. It was believed that Neanderthals and Denisovans were equally different from Homo sapiens. However, Harvard scientist David Reich managed to refute this.

However, the scientist himself says that such a difference can also be explained by the fact that Denisovans interbred with different types ancient people.

The point of view of the German scientist Johannes Krause

German geneticist Johannes Krause from the University of Tübingen believes that the fragments found should not be ignored. Together with his colleagues, the scientist is studying the genome of the Denisovan man for the presence of traces of interbreeding. The fact is that the Denisovan teeth found are very large for this type of ancient man. It seems that its immediate ancestor was a primitive species.

According to the professor, the strangeness with teeth may well be explained by the version that the Denisovans interbred with archaic versions of people. Moreover, according to the professor, most likely it was a species already known to us, since most of them have not been studied at the gene level.

What do London scientists say?

London researcher Chris Stringer from a museum in the UK believes that while settling in Europe and Western Asia, he could well meet Denisovan man, which led to mass crossing. Also, an upright can be an excellent option, since it was common in many territories and could meet Denisovans.

Of course, these disputes can be resolved using the usual DNA analysis of all these species, but this is impossible, since they simply have not been preserved. Most hominins lived in hot environments, and therefore the genome was not preserved in their remains, unlike the remains of Neanderthals and Denisovans, which were found mainly in more severe and cold conditions.

The role of crossing in human nature

To date, many species and subspecies of ancient people, who are our ancestors, are already known. At the same time, one should not deny the fact that after they left Africa, they mated with many other species. It is likely that some more interesting genomes will be identified in the future.

At the moment, it is already known that mass crossings occurred constantly, including with as yet unidentified hominins. According to many scientists, interest in other species arose about 700 thousand years ago.

On the basis of the conducted research, it can be concluded that at some point in time, human evolution was divided into several lines, one of which subsequently led to the Denisovan man, and the more ancient ancestors of Homo sapiens and Neanderthals came out of the other. Scientists also found that Neanderthals, Denisovans and other species of Homo Sapiens lived in Altai for some time and interbred with each other. In addition, crossing occurred with other species that were encountered by Denisovans in different periods of time and in different territories.

It is a pity that the DNA of other types of ancient people was not preserved, otherwise this connection could be traced more clearly. but modern sciences about a person do not stand still, and perhaps soon we will learn something new about our origin.

Bence Viola / Max Planck Institute for Evolutionary Anthropology

The teenage girl, whose bone fragment was recently discovered in the Denisova cave, was the daughter of a Neanderthal woman and a Denisovan man, according to Nature. For the first time, scientists have found a direct descendant of two extinct species. Presumably, such mixed unions were quite common.

Denisovan man is an extinct species or subspecies of people who inhabited South and East Asia and died out about 40 thousand years ago. What the Denisovans looked like is unknown, since so far several molars and individual bones or their fragments have been found. But thanks to the decoding of their genome, it turned out that the Denisovans interbred both with modern people and with Neanderthals, with whom they split, according to various estimates, from 390 to thousands of years ago. In Denisova Cave, not only the remains of Denisovans were found, but also the bones of Neanderthals from the so-called Altai population, which lived in Siberia about 120 thousand years ago.

In 2014, in the Denisova Cave, archaeologists discovered a fragment of a long bone of the Denisova man (Denisova 11). Radiocarbon analysis showed that the Denisovan lived more than 50 thousand years ago. Researchers from Germany, Russia, Canada and the UK, led by Svante Paabo of the Max Planck Institute for Evolutionary Anthropology, analyzed the thickness of Denisova 11's bone and suggested that it was an adolescent 11-13 years old. They also determined the sequence of the complete genome and found out that it was a girl.

To determine whether it belonged to Neanderthals or Denisovans, the authors of the work compared the Denisova 11 genome with the reference genomes of Denisovans and Altai Neanderthals. It turned out that in the girl's genome, 38.6 percent of the alleles correspond to the Neanderthal, and 42.3 percent to the Denisovan genome.

Then the scientists compared the number of transversions (mutations in which a purine base in DNA is replaced by a pyrimidine one and vice versa) in the Denisovan genome with mutations in the Denisovan and two Neanderthal genomes (European and Altai Neanderthals). Judging by the degree of difference between the genomes, the girl's genome contained one set of Neanderthal and one Denisovan chromosomes.

In addition, the researchers were able to determine the origin of the parents of the Denisov girl. Her mother turned out to be genetically more similar to the European Neanderthals who lived on the territory of modern Croatia about 30 thousand years ago, and not to the Altai population. Presumably, its ancestors and the Altai Neanderthals split about 140 thousand years ago, and this population separated from the European branch about 100 thousand years ago. The father of Denisova 11 also had a Neanderthal ancestor who lived 300-600 generations before him.

Suggested family ties and gene transfer between Neanderthals and Denisovans.

V. Slon et al. / Nature, 2018

Scientists believe that when ancient people met, they often interbred with each other. Another thing is that such an opportunity was limited, the habitats of Neanderthals and Denisovans overlapped little. It is possible that the mixed descendants of the two species were less viable than purebreds, and therefore Neanderthals and Denisovans did not mix, but survived as separate species.

According to the head of Russian archaeologists, scientific director of the Institute of Archeology and Ethnography of the Siberian Branch of the Russian Academy of Sciences, Academician Anatoly Derevyanko, he expressed two hypotheses regarding the coexistence of Neanderthals and Denisovans.

“The first is antagonistic, when two species compete up to mutual destruction and even the consumption of their own kind for food. This is supported by the absence of objects of the Neanderthal industry in the Denisova Cave - only fragments of the remains of themselves. Although, I note that in the Okladnikov cave, located 45 km (in a straight line), a sufficient number of Neanderthal stone products were found, more archaic compared to Denisovans.

The second hypothesis is that there were complementary relationships between Neanderthals and Denisovans, up to interbreeding. In favor of this option is last discovery... In the same eleventh layer, a fragment of a human bone was found in 2016, so tiny that it has not yet been possible to establish its exact place in the skeleton. But sequencing of the DNA obtained from the bone showed that this girl, at least 13 years old, was a hybrid of a Neanderthal and a Denisovan, and in the fourth generation. Note that mixed-breed offspring of different species (for example, horses and donkeys) are not capable of further reproduction. Since Neanderthals and Denisovans interbred repeatedly, this implies that they belong to the same biological species, with all the already established cultural and genetic differences.

This is an extremely important fundamental discovery. Denisovans and Neanderthals interbred with early people modern look, formed in Africa 200–150 thousand years ago. All this testifies to the unity of the biological species that settled in Africa and Eurasia...”, says Derevyanko.