It was believed that the genes of only two ancient species of people took part in the “construction” of modern man. But it turned out that there a third one. And this is not the Creator after all.
We all know that the ancient ancestors of the inhabitants of West Africa are not like everyone else. Genetics have found multiple confirmations of this.
It turned out that in the genome of Africans there is DNA “wandering” that belongs to species of people unknown to science.
Besides Neanderthals and Denisovans, there is someone else involved here.
Who are these “suspicious people”? To whom and what did they “inject” as an inheritance?
Gene code: ancient ancestors
The last 10 years of genetic research have been quite productive. Scientists have found out that Neanderthals and Denisovans are our closest ancestors. Their genes can be clearly traced in the genome of modern humans.
Moreover, the inhabitants of Eurasia have more Neanderthal genes, while the inhabitants of Australia and Oceania have more Denisovan.
It is believed that a mixing occurred after humans spread outside of Africa.
In 2016, scientists decided to find out what percentage of DNA from extinct people we inherited. And here a surprise awaited them.
It turned out that many genes that were attributed to Denisovans have nothing to do with this species of people at all.
Although it was clear that they belonged to some ancient ancestor unknown to science. Thus, the research resulted in more questions than answers.
Where does the trace come from?
The greatest difficulty of the study was the lack of the required amount of genetic material.
If Neanderthals have been studied quite well, then researchers only got a phalanx of a finger and a few teeth from Denisovan man. But this is valuable, because it allowed us to obtain a lot of information.
But why was there no data about the “new” species of ancient man before? Because not even a little bit of their trace of remains, no teeth, no bones, not even tools.
It is believed that the genome of Homo sapiens mixed with the Denisovans – inhabitants of South Asia or Eastern Indonesia. Scientists have suggested that it was these populations that crossed with a “ghost species” unknown to science.
New methods
Without the necessary genetic material, the research would be at a dead end if not for modern technology.
In 2020, American geneticists from the University of California, proposed a new method of gene modeling. Thanks to it, it became possible to find traces of extinct unknown ancestors “without their participation.”
Geneticists Arun Durvasula and Sriram Sankararaman tested the new method primarily on the West African Yoruba and the Mende people. The testing results were published in the journal Science Advances.
For their research, a group of scientists developed a program that inserted into the DNA of modern humans known parts of the genome of their ancestors: Neanderthals and Denisovans. A kind of “trial” began using computer modelling.
Single nucleotide polymorphisms were used as genetic markers, which make it possible to recognize genetic variations.
We won’t go into how exactly this works in genetic science, but with the help of these markers we were able to establish that there is a specific section of DNA that does not belong to either one or the other.
Experts have fully analyzed 405 genomes of West Africans. It turned out that they contain from 2 to 19% previously unknown DNA. Scientists have thus concluded that the ancestors of West Africans interbred with species of people that existed before Denisovans and Neanderthals.
The species separated from the common trunk about 625 thousand years ago. And about 200-300 thousand years ago, Neanderthals also mixed with the “ghost species”.
Moreover, in the DNA of Denisovans, researchers also found 1% of the human genome unknown to science. But Denisovans, having crossed with Homo sapiens, gave modern people 15% of their genes.
How did this happen and what was the result?
Scientists explain this by introgression, or growth – hybridization, a long-term process of transferring genetic material.
It becomes possible when representatives of two different genetic groups are first crossed with each other. The result is an interspecific hybrid that is repeatedly crossed with representatives of the parent species.
Well, it’s like a guy from one village traveled far away, fell in love with a girl from another tribe, gave birth to a child there and left for home.
The handsome “hybrid son” remained in his tribe, found a wife and gave birth to more children. And all the other descendants went on to marry and produce offspring in their tribe.
The process of exchange of genetic material occurred between populations of different species and those genes that the “vagrant” ancestor gave to the descendants became “rooted.”
So, the authors of the study came to the conclusion that Homo erectus (upright man) lived simultaneously with Denisovans and Neanderthals on the territory of Eurasia. Perhaps it is this mysterious third species that contributed to the formation of the genome of the ancient inhabitants of West Africa.
This conclusion has been made so far only based on the results of computer modeling.
It is not yet possible to extract DNA from the rare remains of ancient people found in West Africa. The finds are poorly preserved.
However, the fact remains that Africans have genes from previously unknown groups of ancient people. It is possible that we have them too. But this is still a mystery, shrouded in darkness.
Perhaps, the ancestors of all humanity were 22 aliens from another planet – because, supposedly, all people on Earth have 22 types of gene sets. And here – there it is, just three main species.
All that remains is to follow the news. What if archaeologists dig up something and the secret will be revealed?
