Geneticists Discover Neanderthals' Cousins DNA in Modern Humans

Scientists have identified genes from Neanderthal relatives known as Denisovans in the DNA of modern humans.

This information comes from Associated Press.

Denisovans were cousins of Homo sapiens, coexisting and interbreeding with them. Their genetic legacy influences our fertility, immune system, and even how our bodies respond to the COVID-19 virus.

Nobel laureate Svante Pääbo was the first to analyze the Neanderthal genome and initiate research into ancient DNA. He also discovered a hominin known as the "Denisovan."

Recent studies indicate that some African populations have very little Neanderthal DNA, while individuals of European or Asian descent possess between 1% and 2%.

The Denisovan DNA is scarcely noticeable in most parts of the world, but it constitutes 4% to 6% of the DNA in people from Melanesia, a region to the northeast of Australia.

Dr. Hugo Zeberg from the Karolinska Institute in Sweden noted that this might seem like a small percentage, but there were only around a thousand Neanderthals once.

"Half of the Neanderthal genome is still there, scattered in small pieces within modern human DNA," he added.

Therefore, Denisovan genomes likely have a significant impact on modern humans. For instance, Denisovan DNA has been linked to autoimmune diseases such as Graves' disease and rheumatoid arthritis.

Researchers point out that when Homo sapiens migrated out of Africa, they had no immunity to diseases in Europe and Asia, but Neanderthals and Denisovans, who already inhabited those regions, did.

"By interbreeding with them, we rapidly improved our immune system, which was good news 50,000 years ago. In some people, the immune system is too sensitive and turns on itself," said Chris Stringer, a human evolution researcher at the Natural History Museum in London.

Another scientist, Rick Potts, mentioned that a gene related to blood clotting, believed to have been passed from Neanderthals to Eurasians, might have been beneficial around 12,000 years ago but could now increase the risk of stroke in older individuals.

In 2020, research by Zeberg and Pääbo found that the primary genetic factor associated with severe COVID-19 was inherited from Neanderthals. They discovered that Denisovan DNA, on the other hand, protected against severe COVID-19.

The presence of Denisovan genes has also been linked to better adaptation to high altitudes, particularly among Tibetans who have acclimatized to lower oxygen levels.