Denisovan man and other human ancestors. Another Denisovan man found

In the genome of an extinct species, the Denisovan, unusual pieces of DNA were found that apparently came from some other group.

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

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

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

The genome suggests that Denisovans were cousins ​​of Neanderthals - but this has long been known. Their lineage separated from ours about 400 thousand years ago, before splitting into Neanderthals and Denisovans.

This should mean that Denisovans and Neanderthals were equally different from modern humans, but on closer examination Mr. Reich discovered that this was not the case. “Denisovans appear to be further from modern humans than Neanderthals,” says the scientist. For example, scattered fragments that account for up to 1% of the Denisovan genome appear to be more ancient than the rest.

The best explanation for this is that Denisovans interbred with some other species. Or what Mr. Reich himself says happened: “The Denisovans retained the hereditary information of an unknown archaic population, unrelated to the Neanderthals.”

Johannes Krause from the University of Tübingen (Germany) considers the presented data convincing, “they are difficult to ignore.” Mr Krause is one of a number of geneticists who are studying the Denisovan genome in search of traces of interbreeding. The fact is that Denisovans’ teeth are unusually large, as if we were looking at a more primitive species. If Denisovans actually interbred with an archaic species, this might explain everything.

So, what kind of people were these with whom the Denisovans became related? Mr. Krause is betting on a species that is already familiar to us, since many hominins are known only from fossils and have never been subjected to genetic analysis. And many of them could meet Denisovans on their way.

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

A DNA analysis of 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, dry places. Other hominins preferred hot, humid areas where DNA decays quickly. A number of fossils have been found in Asia, the species of which cannot be determined, and scientists are still unsuccessfully struggling to isolate DNA samples from them.

Whoever that mysterious people turns out to be, the main thing is to understand that interspecies crossing was completely common in the history of human evolution. After our direct predecessors left 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 were not above 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 Royal Society discussion meeting on ancient DNA.

In 2008, in the Denisovskaya Cave in the Altai Territory, Russian archaeologists found the remains of ancient people: the bone of the last phalanx of a child’s (girl’s) finger, a molar that belonged to a young male and a phalanx of a toe; There are three fragments in total.

Based on these fragments, a group of researchers led by the Swede Svante Pääbo described a new species of man, called Denisovsky.

Denisovan man had brown eyes, brown hair and dark skin.
It turned out that the mitochondrial DNA of these samples differs from the mtDNA of modern humans by 385 nucleotides, while the mitochondrial DNA of Neanderthals differs from the DNA of Homo sapiens by 202 nucleotides.

Thus, Denisovan man is still closer to Neanderthal man, and their evolutionary divergence occurred about 640 thousand years ago (the divergence of Homo sapiens and Neanderthal man is dated back to 500 thousand years BC).

Traces of hybridization of Denisovan man with Homo sapiens were found: in the genome of Melanesians, about 5% of common genes were found with the read nuclear genome of Denisovan man.

At the same time, the common genes between modern humans and Neanderthals range from 1% to 4% in various populations (with the exception of the indigenous people of Africa, who do not have Neanderthal genes).

Here is the opinion of Anatoly Derevyanko, academician, director of the Institute of Archeology and Ethnography of the Russian Academy of Sciences:

I believe that man of the modern anatomical type was formed from four lines: Homo sapiens africaniensis (the central trunk, from which the largest number of speciations comes), Homo sapiens orientalensis (its subspecies, oriental man), Homo neanderthalensis, which was previously considered the ancestor of man, and then crossed out (I think it needs to be brought back, because in the genome of modern humans up to 4% is Neanderthal) and Homo sapiens altaensis (Denisovan). That is, evolution was not linear, but multifactorial, and Denisovan did not disappear without a trace, but his contribution to the genome of modern humans undoubtedly was.

Along with the remains of Denisovans, beads, rings, and tools were found in the cultural layer of Denisova Cave. In a word, objects characteristic of homo sapiens. However, the finds are 50 thousand years old. Until now, it was believed that Homo sapiens appeared on the land of Altai about 40 thousand years ago.

This (11th) cultural layer of Denisova Cave is a strange, not yet properly explained mixture of Middle Paleolithic artifacts (usually attributed to Neanderthals) and Late Paleolithic artifacts characteristic of sapiens.

A lot of objects made of bone were found here: needles, awls, bases for composite tools. Many decorations were discovered. For example, two fragments of a bracelet. Talking about them, Academician Anatoly Derevyanko noted that in the manufacture of objects 40–50 thousand years old, grinding, drilling, sawing, and polishing were used.

Although it was previously believed that such production techniques appeared 10–15 thousand years ago. It is also surprising that the stone for the bracelet was delivered from Rudny Altai - at least 200–250 kilometers away.

Beads made from ostrich egg shells were also found in Denisova Cave. The decoration should be considered “imported”, because archaeologists found ostrich egg shells only in Mongolia and Transbaikalia. It turns out that many things got into the cave through exchange, “barter.”

According to Anatoly Derevyanko, the Denisovans had a high spiritual culture, because many objects related not only to everyday life, but also to art were found in the cave.

Only five or six needles dating back 32,000 to 34,000 years have been found in excavations in Europe. In one Denisova Cave, where all the finds are older than 40 thousand years, seven needles have already been discovered.
The Denisovan knew how to make things unique for his era! And these are not rarities, not luxury items, but everyday clothes and shoes.

Is the discovery of the remains of Denisovans among the “smart” objects of human life connected with the fact that they, like homo sapiens, had a hand in them?

It is also unclear why the remains of Neanderthals were found in Denisova and neighboring caves, while a few bones of Denisovans were found only in one place?

Perhaps they did not leave their dead at their place of residence, but buried them in separate places. Archaeologists can only dream that at least some of these paleocemeteries have survived despite climate change.

And yet, why did Altai man, at one time the most developed, after existing for 250 thousand years, ultimately die out?

In the photo: Denisovo man (reconstruction)

Http://ru.wikipedia.org/wiki/Denisovsky_man

Denisova Cave is located in the valley of the Anui River, 4 km from the village of Cherny Anui, Altai Territory.

The diagram shows the difference in the mitochondrial genomes of modern humans (living and late Pleistocene), Neanderthal and “Denisovan” humans.

Denisova Cave is one of the most famous archaeological sites of the Middle and Upper Paleolithic era. It preserves traces of the activity of ancient man. Employees of the Institute of Archeology and Ethnography of the SB RAS have been excavating in Denisova Cave for many years. Geophysicists, paleobotanists, anthropologists, paleontologists and other scientists work together with archaeologists. The excavations are led by the deputy director of the institute, Doctor of Historical Sciences Mikhail Shunkov. Researchers sifted through cubic meters of soil, but for many years they could not find any remains of ancient people. Apparently, our ancestors did not bury their relatives in caves. And yet, in 2008, unique research was crowned with success - scientists discovered three teeth and a phalanx of the little finger, presumably of a girl of five to seven years old, who lived from 30 to 50 thousand years ago.

The little finger was transferred to the Max Planck Institute for Evolutionary Anthropology in Leipzig. Johansson Krause from the laboratory of paleogenetics, headed by Professor Svante Pääbo (by the way, in the same laboratory last year the Neanderthal genome was deciphered), isolated mitochondrial DNA, from which he compiled the complete genome of the “Denisovan” person. The results of a joint study by Russian and German scientists were published in the journal Nature on March 24 this year.

DNA was extracted from 30 mg of little finger bone powder. Over the past millennia, the molecule has broken down into fragments; scientists have discovered 9908 such DNA fragments. A large number of fragments were deciphered (sequenced) and assembled from them into a “puzzle” - a molecule of mitochondrial DNA of an ancient person. For greater reliability, the genome reconstruction procedure was repeated, taking the DNA of another bone fragment and using a different sequencing technique. The results were reproduced with high accuracy. Scientists believe that the reconstructed DNA actually turned out to be “ancient” and does not contain late “contaminants.”

The researchers compared the deciphered genome with the genomes of 54 modern people, one ancient person from the Kostenki-14 site on the Don, about 30 thousand years old, six European Neanderthals and two Neanderthals discovered in the Teshik-Tash grotto in Uzbekistan and in the Okladnikov cave in Altai (in a hundred kilometers about Denisova Cave). The total size of the mitochondrial genome in all three human species and chimpanzees turned out to be almost the same - 16,550-
16,570 base pairs.

It turned out that the man from Denisova Cave is genetically as far from modern man as he is from Neanderthal man. Moreover, the differences in the genome of the “Denisovan” and modern humans are twice as large as the genetic differences between modern humans and Neanderthals. The last common ancestor of all three human species lived about a million years ago, and sapiens and Neanderthals diverged about 466 thousand years ago.

Based on the analysis of mitochondrial DNA alone, it is impossible to say for sure how “Denis” man was related to sapiens and Neanderthals. The morphological characteristics of a species are determined not by mitochondrial, but by nuclear DNA. Research shows that the information contained in mitochondrial and nuclear genes does not always coincide. The mitochondrial genome is sensitive even to occasional interspecific hybridization, and only the nuclear genome carries exclusively species-specific characteristics.

Nevertheless, it is already clear that 30-50 thousand years ago the population of Altai was genetically diverse: people of different genetic lines (Neanderthals, sapiens and Denisovans) lived together in the same territory. Archaeological evidence confirms this. The layer of Denisova Cave, where the little finger was found, contains a mixture of objects typical of the Middle Paleolithic (most likely left by Neanderthals) and Late Paleotic objects made by sapiens. Archaeological finds show traces of continuity, mixing and flow of different cultures into each other.

Currently, there are two theories of the formation of modern man. Some researchers believe that it originated in Africa. Others adhere to the multiregional hypothesis, according to which sapiens also originated in Eurasia. One of the authors of the article under discussion, Director of the Institute of Archeology and Ethnography of the SB RAS, Academician A.P. Derevyanko, is a supporter of the multiregional theory, according to which the blood of not only a small group of African sapiens flows in our veins, but also Neanderthals, and perhaps Asian archanthropes. The results of studying mitochondrial DNA (mtDNA) of a person from Denisova Cave cannot serve as a strong argument either for or against his theory. But still, the emerging image of three unrelated groups of people living together on the same territory, combined with continuity and mixing of cultures, gives this version plausibility.

By the way, quite recently the theory of A.P. Derevianko received another brilliant confirmation. The journal Science, published on May 7, published an article by the same group of German scientists from the Max Planck Institute for Evolutionary Anthropology in Leipzig reporting the complete decoding of the Neanderthal nuclear genome. Now there is practically no doubt left - Neanderthal blood flows in the veins of modern Europeans and Asians.

Leipzig, Germany, under the leadership of Kay Prüfer and Svante Pääbo, studied the nuclear genome of a Neanderthal lady who lived in Altai about 50 thousand years ago. Like any serious research, this work has a backstory. Svante Pääbo and his colleagues began sequencing the Neanderthal nuclear genome back in 2006. This is not an easy task, since ancient DNA has long fallen into pieces and is often contaminated with nucleic acids from microbes and modern humans. However, in 2010, they found out that Neanderthals gave their genes to Homo sapiens living outside of Africa.

Now scientists have obtained a refined version of the genome, in which the position of each nucleotide has been adjusted at least 50 times.

Bence Viola Phalanx of a Neanderthal woman's finger

The material for the study was DNA from the phalanx of the ring or little finger of an adult woman who lived in Denisova Cave in Altai. The phalanx was found in 2010 by Denisova Cave researchers Anatoly Derevyanko and Mikhail Shunkov and transferred for analysis to Leipzig.

The Neanderthal population of Denisova Cave should not be confused with Denisovans.

They lived there a little later, about 40 thousand years ago, and although they were related to Asian Neanderthals, they represented an independent group of the genus Homo. by the same group of researchers led by Svante Pääbo and also from the phalanx of the finger.

The genome showed that the parents of the Neanderthal woman were closely related. These were relatives or cousins, or maybe uncle and niece, aunt and nephew, grandfather and granddaughter, grandmother and grandson. Scientists have concluded that consanguineous marriages were common among Neanderthals and Denisovans because they lived in small groups and were limited in their choice of mates. Researchers believe that the number of Neanderthals and Denisovans was steadily declining at that time, their time was coming to an end.

A comparison of the genomes of Neanderthals, Denisovans and modern humans showed that different groups of hominids in Late Pleistocene, 12-126 thousand years ago, met, communicated and left offspring.

Gene exchange did not occur often, but quite regularly.

Bence Viola Excavations in Denisova Cave

About 77-114 thousand years ago, Neanderthals split into Asian and European populations. Neanderthals who lived in the Caucasus exchanged genes with the ancestors of modern Eurasians and inhabitants of Australia and Oceania, Altai Neanderthals with Denisovan people, Denisovans from unknown caves with the ancestors of modern inhabitants of mainland Asia and American Indians.

The Neanderthal contribution to the genome of modern Eurasians is, according to researchers, from 1.5 to 2.1%.

And the genome of Denisovan man, unlike Neanderthal man, contains 2.7-5.8% of the DNA of some unknown ancient hominids. They may have separated 1.2-4 million years ago from the ancestors of modern humans, Neanderthals and Denisovans. Researchers do not rule out that this mysterious ancestor is Homo erectus, the fossilized bones of which anthropologists have found, but whose DNA sequence has not yet been deciphered. Further research will show whether this is true.

Scientists have compiled a list of DNA sequences that distinguish modern humans from our closest extinct relatives. The list of differences turned out to be quite short. The changes also affect genes responsible for cell division and regulation of other genes. In order to find out how these modifications affected the appearance of modern man and his biology, geneticists need to work further.

(Man from Denisova Cave (Denisova hominin))- probably a new species of extinct people, known from extremely fragmentary material discovered in Denisova Cave. This is the second species of extinct hominin for which complete mitochondrial and almost complete nuclear genomes have become known, which shed light on the identity of these remains. The species lived about 40,000 years ago and had a range that overlapped in time and place with the territories inhabited by Neanderthals and modern humans, but their appearance was caused by migrations from Africa, other than relocations Homo erectus Neanderthals and modern humans.

Opening

Denisova Cave was first explored in the 1970s by Russian paleontologist Nikolai Ovod, who was looking for remains of cave bears but found primitive tools. In 2008, Mikhail Shunkov from the Russian Academy of Sciences, together with other Russian archaeologists from the Institute of Archeology and Ethnography of Novosibirsk, explored the cave. They found a finger bone from a juvenile hominin. Artifacts, including a bracelet, that were excavated from a cave at the same level have been dated by radiocarbon dating and isotope analysis to around 40,000 BC. Continuing excavations, scientists came to the conclusion that the activity of primitive people in this cave was continuous and began around 125 thousand years BC.

Fossils

Only three fragments were found: the bone of the last phalanx of a child’s finger (based on sequencing results it turned out that this was a girl), a whole molar tooth that belonged to a young male (its size is extremely large compared to other Homo) and phalanx of the toe.

Genome

A team of scientists from the Leipzig Institute for Evolutionary Anthropology of the Max Planck Society, led by Swedish biologist Svante Pääbo, sequenced DNA taken from a fragment of a phalanx bone of a child's finger found in 2008 by Russian archaeologists in the Denisova Cave in Altai. It turned out that the mitochondrial DNA of this sample differs from the mtDNA of modern humans by 385 nucleotides, while the mitochondrial DNA of Neanderthals differs from the DNA Homo sapiens 202 nucleotides each. An article dedicated to this discovery was published in the journal Nature on March 24, 2010. Later, when sequences associated with the nuclear genome were processed, it turned out that Denisovan man was still closer to Neanderthals, and their evolutionary divergence occurred about 640 thousand years ago.

The age of finds discovered in the cave in the same layers was determined using radiocarbon dating to be 40,000 years old.

The genome of Denisovan Man, read roughly in 2010, was able to be sequenced “white” (with 30-fold coverage) thanks to new methods of working with ancient DNA. Analysis of the Denisovka genome confirmed that sapiens, after leaving Africa, interbred with the archaic Eurasian population - Neanderthals and Denisovkas. The study also showed that Denisovka were a small population with extremely low levels of genetic diversity. The most important result is the compilation of a detailed catalog of genetic changes that were fixed in sapiens after their separation from their common ancestors with Denisovka. Some of these changes affected genes that influence neuronal function and brain development. This means that there could be genetically determined differences between the psyche of Sapiens and Denisovans.

Traces of hybridization of Denisovan man with Homo sapiens. In the genome of Melanesians, about 5% of genes were found to be in common with the read nuclear genome of Denisovan man. At the same time, modern humans and Neanderthals share from 1% to 4% of common genes in different populations (with the exception of Africa, where Neanderthal genes are practically absent).

Range and hybridization

Traces of hybridization between Denisovan man and Homo sapiens (modern man) have been found. In the genome of Melanesians, about 5% of genes with the read nuclear genome of Denisovans were found. At the same time, modern humans and Neanderthals have 1% to 4% common genes in different populations (with the exception of indigenous people of Africa, in which Neanderthal genes are absent).

The Neanderthal “heritage” is most expressed in the genes of the inhabitants of Europe and Pakistan, Denisovan man - among the inhabitants of the South Pacific region, indirectly indicating the territorial division (area) of these species. It cannot be ruled out that the unique languages ​​of the Papuans of New Guinea are also associated with the Denisovans’ heritage.

The appearance of Denisovans in Asia was probably caused by migrations from Africa, distinct from those of Homo erectus, Neanderthals, and modern humans. “The Denisovans moved out of Africa before humans, from Indonesia they came to the Yangtze and possibly moved upstream,” says academician V.V. Ivanov.

In 2013, anthropologists announced that in ancient times Denisovka independently crossed the Wallace Line. They came to this conclusion by analyzing data on the presence of traces of the Denisovan human genome in the genome of the population of Southeast Asia.

According to a 2013 DNA study, Denisovka, along with Neanderthals, passed on part of the genome to modern humans; It was also established that Neanderthals interbred with anatomically modern people and Denisovka, anatomically modern people - with Denisivka, in addition, Denisovka interbred with a fourth, previously unknown species of people.

Archaeological finds

Closer to the eleventh layer of Denisova Cave, miniature stone needles from bird bones with a drilled eye, beads from ostrich egg shells, beads from animal teeth, pendants from shells, and ornaments from ornamental stone were found. The women's bracelet discovered in the cave was made of a rather fragile chloritolite stone, the nearest rock outcrops of which were recorded in Rudny Altai on the border with Kazakhstan, two hundred kilometers from here. To process the stone, techniques were used that were completely atypical for the early stage of the Upper Paleolithic: machine drilling, internal boring, grinding and polishing. The set of techniques used by the Denisians more than 45,000 years ago in modern humans is typical of a much later era - the Bronze Age.