According to an investigation conducted by Melissa Hubisz and Amy Williams, from Cornell University, and Adam Siepel, from Cold Spring Harbor Laboratory, which has been published in the journal PLOS Genetics, some humans have DNA from an unidentified ancient ancestor.
The researchers developed an algorithm to analyze genomes that can identify segments of DNA that come from other species.
Genomic algorithm
This new algorithm solves the problem of identifying small remnants of gene flow that occurred hundreds of thousands of years ago, when only a handful of ancient genomes are available.
In the study, an algorithm was used to look at the genomes of two Neanderthals, a Denisovan, and two African humans. The researchers found evidence that the 3 % of the Neanderthal genome came from ancient humans, and they estimate that the crossing occurred between 200,000 and 300,000 years ago.
Furthermore, 1 % in the Denisovan genome probably came from an unknown and more distant relative, possibly Homo erectus, and approximately 15% of these 'super-archaic' regions may have been transmitted to present-day modern humans. As one of the authors, Adam Siepel, explains:
What I think is exciting about this work is that it demonstrates what can be learned about deep human history by jointly reconstructing the entire evolutionary history of a collection of sequences from modern humans and archaic hominids. This new algorithm Melissa has developed, 'ARGweaver-D', can go further back in time than any other computational method I have seen. It appears to be especially powerful in detecting ancient introgression.
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The news
Some modern humans carry DNA from an archaic and unknown ancestor
was originally published in
Xataka Science
by
Sergio Parra
.