There are several studies and researches going on highly infectious disease coronavirus. There are many experts that have been maintaining that the disease is relatively new. However, a new study has found evidence that the Covid-19 pandemic had hit humanity more than 20,000 years ago. Researchers said the epidemic was devastating enough to leave an evolutionary imprint on the DNA of the people of East Asia. According to the research, published in Current Biology, an ancient coronavirus disease plagued the entire region for several years. The new finding clearly hints that the disease could have dire implications if it is not controlled soon. It is pertinent that scientists have been pressing on the need of vaccinating as many people as possible at the earliest in order to control the spread. The study was led by evolutionary biologist David Enard. According to the researchers of the University of Arizona, the study should ‘make us worry.’ “The situation that we are facing today might not be new. It might be going on for generation and generation,” Enard said.
Till now, scientists could not go back very far in history to know more about the family of pathogens. Researchers know that there are three coronaviruses that have adapted to infect human beings. They are COVID-19, SARS and MERS. All of them can cause severe respiratory disease. Studies conducted on each of them clearly hint that they passed into human species from bats or other mammals. There are four other types of coronaviruses that can infect humans. But they usually cause only mild colds. Scientists have not directly studied how these coronaviruses became human pathogens. This is why they have no other option but to rely on indirect clues to estimate when jumps happened. What researchers know about the virus is that it mutates roughly at a regular rate. So they can have a rough estimate about when they diverged from their ancestor by comparing their genetic variations. The latest of these mild coronaviruses is called HCoV-HKU1. Researchers found that it crossed the species barrier in the 1950s. The oldest of them is called HCoV-NL63. It may date back as far as 820 years. Enard and his colleagues applied a non-conventional method to know about the virus. Instead of studying the genes of the coronaviruses, researchers looked at what impact they had on the DNA of their human hosts.
The viruses may go through enormous amounts of change. If a mutation protects against viral infection, it may make big difference. If there is a lifesaving mutation, the proteins of the virus might be chopped apart. But these viruses can evolve and a series of changes may result in the host evolving even more counteroffensives. Also, a gene becomes more common due to random new mutations. If this happens, all other versions of that gene become rarer. Enard and his colleagues compared the DNA of thousands of people around the world. They tried to find out the combination of genes known to be crucial for coronaviruses. 42 of these genes in East Asian people had a dominant version. This was a clear indication that these people had adapted to an ancient coronavirus. Enard and his team members also found that antiviral mutations of all those genes evolved sometime between 20,000 and 25,000 years ago.
