Based on genomic analysis, COVID 19 originated in bats. Based on differences from bat COVID, it’s been mutating for 40 years.
Published 12 months ago. I can understand some of the words in the article: some of them seem to mean that not everybody agreed with their theory.
bump, cause this is interesting.
Based on differences from pangolin covid.
We therefore hypothesize that, instead of convergent evolution, the similarity of RBD between SARS-CoV-2 and pangolin_2019 was caused by an ancient inter-genomic recombination. Assuming a synonymous substitution rate of 2.9 × 10− 3/site/year, the recombination was estimated to have occurred approximately 40 years ago (95% HPD: 31–69 years; divergence time (t) = divergence (dS)/(substitution rate × 2 × 3), considering dS in RBD is 3-fold of genome average). The amino acids in the RBD region of the two genomes have been maintained by natural selection ever since, while synonymous substitutions have been accumulated. If this is true, SARS-CoV-2 may have circulated cryptically among humans for years before being recently noticed.
Yeah, the 40 years is an estimate for when it diverged from a known pangolin coronavirus sample. The article says it is actually more closely related to a bat coronavirus, but doesn’t give an estimate for divergence from that. So it’s been “mutating separately from it’s closest pangolin coronavirus relative for 40 years”. Like all other RNA or DNA-based propagators it’s “been mutating” for forever.
The more interesting hypothesis they make based on their data is actually that this branch of the coronavirus circulated for several years in humans before it caused a pandemic.
That sounds utterly implausible to me. If there’s one thing we know about the COVID-19 virus, it’s that it has a very high human-to-human transmissibility. Unless it were only found in Sentinel Islanders or something, if it were present in humans for that long, it would have gone pandemic far earlier.
Unless they’re saying that the high transmissibility was a recent mutation, circa late 2019, and that the virus without that mutation was present in humans earlier. But that’s a significant enough mutation, if so, that I think it’s hard to justify calling it “the same virus”.
It seems like the obvious implication of the “it’s been around for a few years” hypothesis is that some recent mutation greatly increased its transmissibility among people. I think that’s a fairly common history of a new-to-humans pathogen.