Paleogeneticists from the United States discovered in the DNA of Denisovans and Neanderthals traces of an extremely ancient population of people, which separated from the common tree of human evolution almost 2 million years ago. They met a common ancestor of the Denisovans and Neanderthals about 750 thousand years ago, scientists write in the journal Science Advances.
“We recently learned that the ancestors of modern inhabitants of Eurasia came into contact with ancient people, Neanderthals and Denisovans. Europe and Asia, "write Alan Rogers, professor at the University of Utah at Salt Lake City (USA), and his colleagues.
10 years ago, Russian anthropologists and paleogeneticist Svante Paabo announced the discovery of the so-called Denisovans, a previously unknown species of people whose remains were found in the Denisova Cave in Altai. Scientists managed to make this discovery due to the fact that they were able to extract and study fragments of the Denisovans' genome, preserved inside the teeth and knuckles.
Initially, their discoverers believed that the ancient inhabitants of Altai were relatives of the Neanderthals who lived in the Denisova cave about 50 thousand years ago. Subsequently, it turned out that the Denisovans appeared much earlier and were a separate subspecies of people, traces of whose DNA were preserved in the genomes of modern Polynesians, Indians of South America and a number of peoples of Southeast Asia.
The similarities in the DNA structure of Denisovans and Neanderthals, Rogers says, led many scientists to believe that they were close relatives, whose common ancestor left Africa about 600-800 thousand years ago. In the past five years, scientists have fiercely argued about what exactly happened next and when the "purebred" Homo neanderthalensis and their Altai "cousins" appeared.
In particular, Rogers and his colleagues suggested three years ago, comparing the DNA of Neanderthals and Denisovans, that their ancestors separated unexpectedly early, about 700 thousand years ago. Their opponents, anthropologists, believe that this happened much later, citing the fact that the small size of the populations of ancient people distorted the results of Rogers' calculations.
The first people of the Earth
These discrepancies and controversies, as Rogers found out, were generated by the fact that the DNA of Neanderthals and Denisovans hides traces of another, much more ancient population of people, genetically extremely distant from all other known representatives of the genus Homo.
Paleogeneticists came to this conclusion using a new technique that allows one to find common features and differences in the genomes of modern Eurasians, Africans, as well as Neanderthals and Denisovans. Comparing how common and unique mutations were common for each of these representatives of the genus Homo, scientists tried to understand whether traces of previously unknown groups of ancient people are hidden in their genomes.
A large number of common mutations in the genomes of Neanderthals and Denisovans, as well as their absence in Europeans and Africans, indicated that the common ancestor of the first two species came into contact with a previously unknown and very ancient human population. The number of this group of ancient Homo was quite large, reaching 20-50 thousand individuals.
Scientists' calculations show that its representatives separated from the common tree of human evolution about 2 million years ago. This suggests that these ancient hominids are among the Homo erectus, erectus people, the oldest "Eurasian" remains of which were found in the Georgian Dmanisi at the end of the last century.
Representatives of this ancient species of hominids, as the calculations of Rogers and his colleagues show, existed in Eurasia for a very long time.According to the researchers, they should not have disappeared earlier than 750 thousand years ago, when they met the first populations of the common ancestors of Neanderthals and Denisovans who left Africa. Subsequently, as scientists suggest, these people could additionally contact with Altai Homo.
These ancient people, according to researchers, experienced approximately the same fate as the Neanderthals and Denisovans themselves, who disappeared about 50 thousand years ago under the onslaught of new "migrants" from Africa, the ancestors of modern Homo sapiens. Studying their genetic heritage, Rogers and his team hope, will help uncover the mystery of their disappearance and reveal their role in human evolution.