A “gigantic fraction” of our genome comes from an ancient reproductive partner of prehistoric humans, who may have interbred with two distinct super-archaic species.
Apparently, we may actually be only 80% “human”. According to a new study, 1/5 of our DNA appears to have been bequeathed to us by a mysterious hominin that separated from our lineage more than a million years ago.
At some point before our ancestors left Africa, prehistoric humans crossed with this species unknown, beginning a long and complex succession of encounters between different lineages of hominins.
In this case, the mysterious ancestral species is designated “super archaic“, because separated from the clade of modern humans before the split between our lineage and that of our closest “archaic” relatives, the Neanderthals and Denisovans.
Recent genetic studies have between a super-archaic population and the African ancestors of all A wise man.
At the same time, it has also been shown that super-archaic hominins interbred with the Eurasian ancestors of Neanderthals and Denisovans, before later reproduce with the Denisovans themselves.
However, it remains some uncertainty regarding the possibility that all these episodes of genetic mixing have involved the same super-archaic populationa, or whether they existed various stakeholders.
In an attempt to clarify this issue, a team of researchers from the University of Utah, in the USA, analyzed the distribution of genetic variants between modern humans, Neanderthals and Denisovans, with the aim of determining to what extent they shared ancestry.
The conclusions of the , pre-published last week in bioRxivindicate that two distinct super-archaic populations participated in these prehistoric encounters.
Although researchers cannot say exactly when these episodes occurred, they were able to show that the hominin that interbred with archaic Europeans separated from the human lineage earlier than the species that reproduced with the ancestors of modern humans in Africa.
The calculations also indicated that 19.6% of the modern human genome is, in fact, inherited from this super archaic Africanin line with the results of another , from 2025, which estimated that it comes from this former reproductive partner.
In contrast, only 2% of our genes are inherited from Neanderthalswhich has become much more recently.
“20% is a huge fraction. When you get numbers like a 20-80 split, it looks more like the merging of two populations than a small gene flow into an existing population.” Alan Rogersprofessor at U.Utah and lead author of the study, at .
“It’s as if the modern humans were a kind of mosaic. They are simply the combination of two ancestriesnone of which represented a small part of the total”, adds the researcher.
A The big question, of course, is related to the identity of these contributions super archaic. As a hypothesis, the researchers point out that the The man stood up It first left Africa and spread across Eurasia about two million years ago, before the ancestors of Neanderthals and Denisovans began their own expansion out of Africa about 700,000 years ago.
“These groups will have found the descendants of the original wave leaving Africa”, says Rogers. “Therefore, we think that there must have been crossings between ancestors of Neanderthals and Denisovans and these descendants of The man stood up in Eurasia.”
As for the super-archaic population that interbred with our own ancestors, what is known is that this hominin separated of our lineage about 1.3 million years agos, before the separation between modern Africans and Europeans. Beyond that, however… “there are no suspects,” says Rogers.
