DNA from an unidentified ancestor can still be found in people living today

Hyperaxion Aug 7, 2020

Thanks to a new algorithm, genomic analysis revealed the presence of genes belonging to an unidentified ancestor in humans living today.

A new analysis of ancient genomes revealed that the human family tree is even more complex than previously thought. According to a team of researchers at Cornell University and Cold Spring Harbor Laboratory, both in the United States, some people still carry the genes of an unknown ancestor. The discovery was published this week in the journal PLOS Genetics.

DNA from an unidentified ancestor can still be found in people living today
(Credit: Pixabay).

For thousands of years, Homo sapiens coexisted and lived with other species of hominids, such as Neanderthals and Denisovans. They produced offspring – and genes from these other hominid species can still be found in our DNA.

In the new article, the researchers developed an algorithm to identify segments of DNA that may have come from other species, even though this genetic exchange occurred thousands of years ago. The genomes of two Neanderthals, one Denisovan and two African humans were studied.

According to the article, the researchers found evidence that 3% of the Neanderthal genome came from ancient humans and that interbreeding took place between 200,000 and 300,000 years ago.

In addition, 1% of the Denisovan genome probably came from an unknown and more distant relative, possibly Homo erectus – and about 15% of these “super-archaic” genes may have been passed down to humans living today.

The new findings confirm previously reported cases of genetic exchange between ancient humans and point to new cases of interbreeding.

The researchers believe that genetic exchange probably happened whenever two groups coexisted in a given region in the same period.

The new algorithm may be the solution to a major problem in genetic research today: the lack of ancient DNA available for study.

With current technology, we cannot study most of the ancient genes of our ancestors, but the authors believe that the new algorithm will enable the detailed study of genomes that have already been analyzed with other technologies.

“What I think is exciting about this work is that it demonstrates what you can learn about deep human history by jointly reconstructing the full evolutionary history of a collection of sequences from both modern humans and archaic hominins,” said Adam Siepel, co-author of the research, in a statement. “This new algorithm is able to reach back further in time than any other computational method I’ve seen. It seems to be especially powerful for detecting ancient introgression.”

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