What's your estimate of the relative prevalence of an FCS among the likely space of lab-created SARS-like coronaviruses vs. among natural, SARS-like coronaviruses? My understanding is that adding an FCS is a very common method of lab gain of function, but rare among such viruses in nature.
I don't think the FCS is determinative, and I agree Wade's article overstates its significance. In a Bayesian analysis, it still seems to me like it points weakly (at least 3x prevalence?) towards lab origin, though.
Could you at least make a guess at the relative frequencies? My understanding was that hundreds of animal sarbecovirus strains are known, and of those only the two that you note above had an FCS (and not the rare CGG). On the other hand, I understand that adding an FCS is a common technique for lab gain of function, so that perhaps 5% of genetically-engineered SARS-like viruses would have one. That's how I got my ~3x.
It would be nice if each individual piece of evidence were all or nothing, either perfect evidence of lab origin in itself or perfectly irrelevant. I don't think real evidence usually comes that way, so it seems valuable to me to try to quantify even weak evidence.
And not that Nobel laureates don't have an unfortunate history of incorrect beliefs later in life: but I assume you're aware David Baltimore considers the FCS significant? He doesn't seem to have said anything else obviously crazy (unlike Mullis, Pauling, etc.), at least.
I don't think the FCS is determinative, and I agree Wade's article overstates its significance. In a Bayesian analysis, it still seems to me like it points weakly (at least 3x prevalence?) towards lab origin, though.