Australian and American geneticists have found a set of adaptations in the DNA of modern East Asians, indicating that about 25-5 thousand years ago, humanity survived an epidemic of a virus similar to the causative agent of COVID-19. The scientists’ findings were published in an article in the bioRxiv electronic library.
“We have followed the evolution of dozens of genes directly related to the response of the human body to coronaviruses. This evolutionary analysis showed that the ancient inhabitants of East Asia began to come into contact with viruses similar to SARS-CoV-2, about 25 thousand years ago,” they write researchers.
Scientists have been trying for quite a long time to understand where and when a new type of coronavirus arose, which caused the worldwide pandemic of the COVID-19 disease, as well as when it began to be transmitted from person to person. There is still no consensus among epidemiologists on this score.
In particular, biologists cannot yet say for sure where and when this virus arose, which animals, including bats and pangolins, acted as its intermediate carriers, and what role in its formation was played by the so-called recombination, the exchange of genetic material between different types. coronaviruses.
Many scientists today suggest that the ancestor of SARS-CoV-2 began to spread among bats in East Asia relatively long ago, back in the middle of the last century. Discoveries like these make researchers wonder how often animal coronaviruses emerge, which can infect humans as effectively as the causative agent of the COVID-19 epidemic.
Evolutionary history of coronaviruses
A group of evolutionary biologists led by David Enard, associate professor at the University of Arizona in Tucson (USA), took the first step towards obtaining such information by studying how the structure of several dozen genes associated with the work of immunity and the penetration of SARS-CoV- 2 and other coronaviruses into the human body.
To do this, scientists have isolated and compared with each other sets of mutations in these genes in the DNA of people who participated in the “1000 genomes” project. The differences in their structure, scientists compared to when the ancestors of the carriers of these gene variations were divided, which allowed them to determine when the variations that contribute to survival from infection with coronaviruses began to spread.
These calculations showed that such changes in the structure of DNA began to appear for the first time among the ancient inhabitants of modern East Asia about 25 thousand years ago, becoming widespread among them about five thousand years ago.
These processes affected mainly those genes that were directly related to the body’s response to COVID-19 and the organs that it affects. This suggests that humanity in the past could already face a similar threat and experienced coronavirus epidemics.
In addition, scientists have found that such genetic adaptations are either absent in the genomes of inhabitants of other continents and regions of Eurasia, or were relatively poorly distributed. This testifies in favor of the fact that East Asia has been an “incubator” of various coronaviruses for several tens of thousands of years, the authors of the article conclude.