The Neanderthals may have died out a long time ago, but tiny amounts of their DNA persist in most modern humans. According to Discover Magazine, many of us have a fraction of 1%, if any, Neanderthal DNA buried deep in our genetic code, though in some portion of the population, that figure could be well over 2%. This has been a fun party-fact to this point—something entertaining but not really meaningful—but according to new research, those small differences in DNA might have an impact on how well a person fares with COVID-19. And suddenly that percentage seems to matter a whole lot, doesn't it?
A study recently published in Nature suggests that about 50% of the population in South Asia and 16% of Europeans have up to 2% Neanderthal DNA. People of African descent often have around 0.3% Neanderthal DNA. It may seem like these numbers have no bearing at all, but these genetic relics from humanity’s past appear to have effects on numerous traits, including skin, hair and eye color. For example, The Scientist states that, when expressed, Neanderthal DNA can cause pale skin that burns easily.
According to Medline, Neanderthals were one of the forms of early humans that lived before us. They populated parts of what are now Europe and Asia for about 360,000 years, finally dying off about 40,000 years ago, but not before interbreeding with what would become modern humans.
We don't really know all of the ways the DNA of each combined or what it may mean in terms of our modern genome. It's possible that our DNA didn’t mesh well in places. The combination may have led to weaknesses in the genome. Or perhaps what were genetic benefits many, many years ago no longer serve the same purpose now. Or there may be some remaining today.
Researchers have found some variations in chunks of our DNA, or alleles, that can have profound effects on health. According to Science, some Neanderthal alleles appear to cause baldness and certain mental illnesses, while others might improve specific immune functions. A certain allele causes difficulties quitting smoking, while another may put sedentary people at greater risk for heart disease.
The differences appear to affect some infectious disease risks as well, which could include resistance or susceptibility to the coronavirus. In a statement to CNN, the researchers revealed that within a tiny cluster of Neanderthal DNA, found on chromosome 3, there’s a bit of code that affects COVID-19 susceptibility. The genetic variation may be small, but it might make a person up to three times more likely to require use of a ventilator if they do catch the virus. Going forward, if we were to implement them, tests to screen for these variations may help doctors plan better treatment strategies and work proactively to prevent severe COVID-19 responses so that those more likely to face severe responses could receive stronger treatment to help prevent that eventuality.
Human DNA is full of surprises, which could come from a few different sources. Our differences are part of what makes us all so wonderfully diverse, but they can also open us up to distinct complications. Future research targeting our genetic variations could provide a springboard to more individualized treatment options for COVID-19, and beyond.
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