However, comparing the composition of complete genomes has one drawback: it does not take into account the rapid recombination with the exchange of individual sections of the genome between different types of viruses. That’s why evolutionary virologist Spyros Lytras and his team at the University of Glasgow analyzed 18 bat and pangolin viruses that are closely related to SARS-CoV-2, each in 27 parts. These genome fragments were each several hundred to several hundred thousand base pairs long. Each segment would have a different evolutionary history, Lytras pointed out.
“This analysis showed that some segments shared a common ancestor with SARS-CoV-2 several years ago. Most of these fragments pointed to a common origin around 2007. But a small segment of the genome of only 250 base pairs could point to a common ancestor.” ancestors in 2016, another 550-nucleotide fragment points to one in 2015. That would be three to four years before the emergence of SARS-CoV-2 in humans,” the Nature author wrote. Lytras would emphasize that primarily due to migration bats – with their harmless viruses – the occurrence of Covid 19 pathogens in southern China and Southeast Asia can be assumed.
However, whether the direct origin of SARS-CoV-2 will ever be determined remains controversial among virologists who study pathogen evolution. The recombination between viruses that takes place all the time in host organisms blurs the picture very quickly. Edward Holmes, a virologist at the University of Sydney: “The chances of this happening are almost nil. This steamer has left.”