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According to a new study, we owe our ability to fight against certain viruses, such as the flu, hepatitis and HIV, to old DNA fragments inherited from our Neanderthal ancestors.
The paper, published today in the journal Cell, states that the interbreeding between Neanderthals and modern humans has left us 152 gene fragments that interact with specific viruses and have hardened our immune system, protecting us against many dangerous diseases.
The conclusion comes from two researchers at Stanford University in California, Dmitry Petrov and David Enard (a former postdoctoral fellow at Petrov's laboratory, currently affiliated with the University of Arizona).
The pair identified gene fragments after combing the scientific literature for modern human genes known to interact with viruses. Their efforts resulted in a complete list of 4,500 genes, of which 152 were transmitted by Neanderthals, reports the Phys.org, citing Stanford University.
Why some people are still 2% Neanderthal
The genomes of Europeans and modern Asians consist of about 2% of Neanderthal DNA. Although much of the initially transmitted genetic material was "suppressed by selection purification", these particular extracts remained stuck for a reason, the authors debate in their study.
"Our research shows that a considerable number of frequent Neanderthal DNA fragments have been adapted for very good reason," said Petrov, an evolution biologist at the Stanford School of Humanities. "The Neanderthal genes have probably afforded us some protection against the viruses our ancestors encountered when they left Africa."
#Humans modern viral defenses inherited from #Neanderthals @CellCellPress https://t.co/xaVVVUTQHw
– Phys.org (@physorg_com) October 4, 2018
In addition, scientists suggest that by studying these DNA fragments left by ancient humans, we could have a clear idea of the viruses and diseases that affected Neanderthals during their passage on Earth.
"It's similar to paleontology," Enard said, citing how fossil traces, such as fossilized footprints, can help scientists get details about long-gone creatures without actually looking at their bones. . "Because we know which genes interact with which viruses, we can infer the types of viruses responsible for old outbreaks."
Ancient Trysts
To explain their theory, scientists take us back in time, 70,000 years ago, when Homo sapiens migrated from Africa to Eurasia, where they met the Neanderthals.
At that time, these ancestors had had hundreds of thousands of years to adapt to the harsh climate of these new lands and had developed a different immune system, designed to fight against specific viruses depending on the region , note the Independent.
Reconstruction of a Neanderthal man at the Neanderthal Museum in Mettmann, Germany.
Einsamer Schütze
/
Wikimedia Commons / Resized
(CC BY-SA 4.0)
This meant that the Neanderthals were carriers of unknown viruses to which Homo sapiens would have been exposed only when the two species met in Europe and Asia and had crossed each other.
But the mix between modern man and Neanderthal man has done more than create new microbes. When both species exchanged viruses, Neanderthals also passed on to our newly migrated ancestors the genetic tools needed to protect themselves from pathogens.
"We call it the poison antidote model," Enard said. L & # 39; Atlantic.
"Modern humans and Neanderthals are so closely related that it was not really a genetic barrier against the occurrence of these viruses. But this proximity also meant that Neanderthals could send us protections against these viruses. "
As Enard explained, the poison antidote model is actually more effective from the point of view of evolution.
"It was much more logical for modern humans to borrow from Neanderthals the already adapted genetic defenses rather than wait for their own adaptive mutations to develop, which would have taken much longer," he said.
Thank you Neanderthals https://t.co/Otr9NXbgWU
– David Rewhorn (@ David_Rewhorn) October 4, 2018
In the study, Enard and Petrov show that the 152 Neanderthal DNA extracts we still possess today are specifically designed to interact with specific RNA viruses, such as HIV, modern influenza A and hepatitis . chemically similar to DNA) as genetic material.
Moreover, these genes are found only in Europeans today, suggesting that Asian populations have benefited from a different host of DNA fragments targeting completely separate viruses. .
According to Enard, all this is perfectly valid because the evidence suggests that Neanderthals have crossed with modern humans at least twice over the last 100,000 years and in different prehistoric places. These cases have probably seen different viruses exchanged between the two species, he said.
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