If you ever thought that Coronavirus types such as SARS-CoV, MERS-CoV, and SARS-CoV-2 were only a recent thing, then this might turn out to be a big surprise for you.
A recent study published in Current Biology suggests that an ancient coronavirus epidemic broke out some 25,000 years ago. While we do not have historical records of how people were affected, a research team from the University of Arizona, the University of California San Francisco, and the University of Adelaide had gathered enough information to conclude that people in East Asia were affected the most and some of their genes underwent rapid changes to combat the infections.
The human genome is a repository of information not just for our cells to function but also to tell us about the events in our ancestral past. So when the COVID-19 pandemic struck, the question arose: Did such previous outbreaks occur before?
“The modern human genome contains evolutionary information tracing back tens of thousands of years, like studying the rings of a tree gives us insight into the conditions it experienced as it grew,” Professor Alexandrov explained.
Researchers have seen that people carrying certain mutations have higher risk to severe COVID-19 infection. But the opposite is also true. Individuals with a different set of mutations might be more resistant to such infections. Such individuals survive outbreaks and pandemics and pass on these advantageous mutations to the next generations. When the pandemic persists for a few hundred years, the proportion of such mutations increases in the surviving population. If the virus mutates and presents itself differently, then the human body creates more mutations to combat the virus and survive the infection, leaving a trail of mutations.
“Computational scientists on the team applied evolutionary analysis to the human genomic dataset to discover evidence that the ancestors of East Asian people experienced an epidemic of a coronavirus-induced disease similar to COVID-19,” Professor Alexandrov continued.
The team scanned the genomes of thousands of people from the 1000 Genomes Project, which is the largest data source of common human genetic variation, looking for mutations in genes that have a role in response to coronaviruses.
What they found was an uptick of mutations in these genes of people from East Asia that is now China, Japan, Mongolia, North Korea, South Korea, and Taiwan. This was a strong signal to suggest that the population had faced a major outbreak and responded to it.
The researchers estimate these mutations set in about 25,000 years ago but accurate prediction of the timing is difficult to pinpoint. The bigger takeaway from the research is the list of genes that are involved in response to coronaviruses, and how we could use this information to target the coronavirus.
While this information is helpful to researchers in the long term, vaccinations, wearing masks, and social distancing might still our best bet to counter the pandemic.