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A team of researchers from Australia and the United States have found evidence of a coronavirus epidemic that erupted more than 20,000 years ago in East Asia, according to a study published Thursday in the scientific journal Current Biology.
In the study, the researchers studied the genomes of more than 2,500 people from 26 different populations around the world. They have identified the first interaction of the human genome with coronaviruses, which has left genetic fingerprints on the DNA of modern people in East Asia.
The genomes they studied contain evolutionary information about humans dating back hundreds of thousands of years, lead author Yassine Souilmi said – information we have only learned to decode in recent years.
Viruses work by making copies of themselves. However, they don’t have their own tools for doing the duplication. “So they actually depend on a host, and that’s why they invade a host, and then they hijack their machines to create copies of themselves,” Souilmi said.
This hijacking of human cells leaves a mark that we can now observe – offering concrete evidence our ancestors were once exposed to and adapted to coronaviruses.
In the genomes, researchers have found these genetic signals linked to a coronavirus in five different populations located in China, Japan and Vietnam. The outbreak may have spread beyond these countries, Souilmi added, but data is not available in other parts of the region, so there is no way to know.
From those populations, Souilmi said the researchers found that an affected group developed a beneficial mutation that helped protect them from the coronavirus. People with the mutation had “an advantage” in terms of survival, he said – meaning that over time the population was made up of more people with the mutation than without.
“Over a long period of time, and throughout exposure, it leaves a very, very clear mark in the genomes of their descendants,” Souilmi said. “And that’s the signature we actually use to detect this old outbreak, and also the timing of this old outbreak.”
The study says the coronavirus plague occurred separately between different regions and spread across East Asia as an epidemic.
However, scientists do not know how ancient people experienced the epidemic, in part because it was not clear whether it was something seasonal like influenza, or ongoing – like the Covid-19 pandemic. – which infects people and continues to spread all the time.
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