Some humans carry genes from an unknown “super archaic” hominin, whose genome has never been sequenced from remains. This is the conclusion reached by a team of American geneticists and computer scientists who have studied gene flow between different populations of modern man and their ancestors, reported RT.
A new algorithm, which the researchers describe in the journal PLOS Genetics, has confirmed several migrations of genes and, presumably, populations, that were known to anthropologists. Thus, approximately 50,000 years ago, the DNA of Neanderthals and another related branch of human evolution, the Denisovans, interbred with modern man from Africa – something that was already known.
However, it has now been discovered that at least 150,000 years prior to those migrations another gene exchange occurred. The Homo sapiens lineage mixed with Neanderthals and Denisovans as well; in such a way that in a late Denisovan, whose DNA they analyzed with the new algorithm, some genes from our most direct ancestors are present.
It has been estimated that 3% of the Neanderthal genome (the team examined two specimens) came from ancient humans. Thus, 1% of the Denisovan genome appears to come from another hominid species, possibly Homo erectus. The three branches of human evolution experienced the genetic influx of those enigmatic “super archaic” beings in the same period, between 200,000 and 300,000 years ago.
Judging by the genetic data, the unknown branch would have separated from the main evolutionary stem of the human race millions of years ago, but later than the ancestors of the chimpanzee (about 13 million years ago). Up to 15% of the DNA regions of that branch found in Denisovan were possibly also transmitted to modern humans, the team found.
The group’s findings point to several previously unknown cases of interbreeding and leave the tree of human evolution even more tangled. The authors believe that this same approach could help us better understand the transformation of the wolf into a dog, among other complex cases.
(With information from RT)
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