(ORDO NEWS) — No one knows who the discovered teenage girl was more than 50,000 years ago, but she turned out to be a “hybrid” ancestor of modern humans that scientists had not found before.
Researchers recently found evidence that she was not alone. In a 2019 study, scientists used artificial intelligence (AI) to identify an unknown species of human ancestor that modern humans came into contact with during their long journey from Africa millennia ago.
“About 80,000 years ago, the so-called exit from Africa occurred, when part of the human population, which already consisted of modern humans, left the African continent and migrated to other continents, giving rise to all current populations,” explained evolutionary biologist Jaume Bertranpetit from the University of Pompeu Fabra (Spain).
As modern humans made their way across the Eurasian landmass, they also interbred with ancient and extinct hominids from other species.
Until recently, Neanderthals and Denisovans were thought to have been among these casual sex partners , the latter of which was unknown until 2010.
But in this study, a third long-standing ancestor was isolated in Eurasian DNA, thanks to deep learning algorithms sifting through the complex mass of ancient and modern human genetic code.
Using a statistical technique called Bayesian inference, the researchers found evidence for what they call a “third introgression,” a “ghostly” archaic population that modern humans interbred with during the Exodus from Africa.
“This population is either related to the Denisov Neanderthal clade or diverged early from the Denisov lineage,” the researchers write, implying that this third population may have been a mixture of Neanderthals and Denisovans.
In a way, this is a hypothetical confirmation of the 2018 teenage girl “hybrid fossil” varieties, although there is still much to be done and the research projects themselves are not directly linked.
“Our theory is consistent with the hybrid specimen recently discovered at Denisova, although we cannot rule out other possibilities for now,” one of the team members, genomist Mayukh Mondal from the University of Tartu in Estonia, said in a press statement during the opening.
At the same time, discoveries made in this field of science are in full swing.
Also in 2018, another team of researchers unearthed evidence for what they called a “certain third interbreeding event” alongside Denisovans and Neanderthals, and papers published in early 2019 trace the chronology of how these extinct species crossed and interbred more frequently than ever before.
There is much more research to be done. The application of AI-assisted analysis is an entirely new technique in the field of human origins, and the known fossil evidence we are dealing with is remarkably sparse.
But, according to the study, what the team found explains more than just the long-forgotten process of introgression it’s fascinating work that partly defines who we are today.
“We thought we’d try to find these places with high divergence in the genome, see which ones are Neanderthals and which ones are Denisovans, and then see if they explain the whole picture,” Bertranpetitt said.
“As it happens, if you subtract the Neanderthal and Denisovan parts, there is still something in the genome that is highly divergent.”
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