Corona epidemic hit 20K years ago, could alter people's DNA, says study

May have dire implications if Covid-19 not brought under control soon

Researchers have found evidence that a coronavirus epidemic swept East Asia some 20,000 years ago and was devastating enough to leave an evolutionary imprint on the DNA of people alive today.

The new study suggests that an ancient coronavirus plagued the region for many years, researchers say. The finding could have dire implications for the Covid-19 pandemic if it’s not brought under control soon through vaccination.

“It should make us worry,” said David Enard, an evolutionary biologist at the University of Arizona who led the study, which was published on Thursday in the journal Current Biology. “What is going on right now might be going on for generations and generations.”

Until now, researchers could not look back very far into the history of this family of pathogens. Over the past 20 years, three coronaviruses have adapted to infect humans and cause severe respiratory disease: Covid-19, SARS and MERS. Studies on each of these coronaviruses indicate that they jumped into our species from bats or other mammals. Four other coronaviruses can also infect people, but they usually cause only mild colds. Scientists did not directly observe these coronaviruses becoming human pathogens, so they have relied on indirect clues to estimate when the jumps happened. Coronaviruses gain new mutations at a roughly regular rate, and so comparing their genetic variation makes it possible to determine when they diverged from a common ancestor.

The most recent of these mild coronaviruses, called HCoV-HKU1, crossed the species barrier in the 1950s. The oldest, called HCoV-NL63, may date back as far as 820 years.

But before that point, the coronavirus trail went cold — until Dr Enard and his colleagues applied a new method to the search. Instead of looking at the genes of the coronaviruses, the researchers looked at the effects on the DNA of their human hosts. 

Over generations, viruses drive enormous amounts of change in the human genome. 

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