About the origin of SARS-CoV-2

Determining the origin of SARS-CoV-2 is of great importance in order to better prevent future pandemics. There are two theories about the origin of SARS-CoV-2: a natural origin and an accidental laboratory leak. But which is more plausible? A recent article by Nicholas Wade, a well known science writer, explores the issue in detail and, after careful investigation, concludes that the laboratory accident theory explains the facts much better than the natural emergence theory. Of course, this conclusion is widely disputed, for example by Larry Moran on his blog. For my part, I find Wade convincing and Moran counter arguments quite weak. But what about you the participants at PS? I’ll be very interested to know what is your take on this issue, especially from those with expertise in virology.

I don’t see the “great importance” part.

What’s important is dealing with the virus. How it got here is secondary.

Did the Wuhan lab create the virus from scratch? That seems extremely unlikely. If the Wuhan lab was involved, then it is more likely that the virus had a natural origin and was being studied by the lab. And perhaps they were careless in how they handled it. But that still leaves us with a likely natural origin.


I think first of all you’re actually presenting a false a false dichotomy. Even supposing for the sake of argument that they studied the virus at the WIV and it subsequently leaked from there -that does not mean it was not previously obtained from some wild population.

So when you say “origin”, what do you really mean?
That the entire virus was created de novo in a laboratory at the WIV?
Or something less extreme such as that researchers at the lab took a natural virus and introduced mutations to it?
Or perhaps even less extreme still, that the WIV was studying the virus which they got from the wild - and it accidentally got out - without them actually having done anything to it?
Perhaps some fourth option entirely.

Depending on which particular option you subscribe to, can you detail what predictions this option makes and show how that best explains the data?


It would be nice to know, but the knowledge won’t have much effect on pandemic preparedness. We know lab leaks occur and we know that zoonotic events occur (much more frequently than lab leaks).

I stopped paying any attention to anything Wade writes after his really very bad book on human genetics and race. (But I did help fact-check the New York Magazine article on the same subject a few months ago.)

I think there is basically zero evidence to decide the question. I find the evidence that I’ve seen offered in support of a lab leak to be quite weak, while the certainty of those who reject it seems inexplicable to me.


Wade is mostly well known for his horrible book.

A best-seller by former New York Times science writer Nicholas Wade about recent human evolution and its potential effects on human cultures has drawn critical reviews since its spring publication. Now, nearly 140 senior human population geneticists around the world, many of whose work was cited in the book, have signed a letter to The New York Times Book Review stating that Wade has misinterpreted their work.

Part of the letter reads as follows:

Wade juxtaposes an incomplete and inaccurate account of our research on human genetic differences with speculation that recent natural selection has led to worldwide differences in I.Q. test results, political institutions and economic development. We reject Wade’s implication that our findings substantiate his guesswork. They do not.

We are in full agreement that there is no support from the field of population genetics for Wade’s conjectures.

Wade once again offers conjectures. In this case, none of the conjectures are supported by anything resembling evidence for accidental lab release of the virus. His entire argument is based on mistrust of individuals involved with early claims that the emergence of the novel virus was a natural event occurring in the wild.

I am not arguing that accidental release is impossible, but it is irresponsible to present two different scenarios as though they are have an equal likelihood of being accurate. There is indeed evidence supporting natural emergence, although it is certainly not foolproof evidence. However, since only one of these two scenarios is supported by evidence, it is - at this point - irresponsible to claim that the two possibilities are equally viable.


No, for if it is the case that the virus escaped a lab following gain of function studies, then this type of studies on potentially dangerous viruses will probably have to be banned.

No, his argument is not based on what you say here, not at all. Did you read his article?

Banning won’t deal with the virus that is already here. So you are speculating about a different issue.

Yes, if the Wuhan lab was involved, there might need to be more careful scrutiny of some kinds of scientific study. But let’s not jump the gun on that. Natural emergence is still the most likely explanation.


I did. You are welcome to refer to any evidence he presented in his article.

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A false dichotomy right from the start!

But then, you find Didier Raoult, who publishes fake data, convincing on COVID-19 and you ignore all of the relevant evidence.

Do you really not realize that science is about evidence, not mere rhetoric?

That’s my take on your take on this issue, as someone with extensive expertise in virology.


I’d like to thank @Giltil for taking the time to present this issue in a balanced manner. There have been behind the scenes discussions on this, and moderators are aware this issue is likely to generate more heat than light. Thanks to all for the serious replies.


In fairness, Wade has some better work, or at least much less horrible, writing for NYT and Scientific American. His book The Faith Instinct makes a plausible case that humans evolved the capacity for religion, and I have recommended it occasionally on this forum.

I think it’s important to note the what Wade does best is to make a case that a hypothesis is plausible, but doesn’t necessary present a complete case, or even direct evidence. This is Wade’s approach to help sell books and articles, but it may be a mostly one-sided presentation. Wade generally hedges (in things I’ve read) when it comes to what actually happened - he hedges in this article too.

And others have noted, the lab leak hypothesis is certainly plausible, but so is a natural origin. Epidemiologists have been warning about just such an event for many years, and the Wuhan region is a known hotspot for new disease. A natural origin of SARS-COV2 from Wuhan should be the least surprising possibility.


I’d like to add my criticism of the report from Steven Quay, referenced by Wade, which presents a Bayesian analysis on the probability that SARS-COV2 is of laboratory origin. I read part of this 193 page report, but stopped when I found serious problems with his methodology. Some of the evidence Quay considers bears on the plausibility of the virus originating from a lab, but Quay interprets this as the probability of lab origin, which is not the same thing. Quay is also appears to be systematically discarding uncertainty in the Bayesian estimates (the posterior distribution), instead treating them as fixed probability at each step. This negates the strength of Bayesian methods which allow that uncertainty to be included.

The scary part is that Quay is scheduled to testify before congress.


Anyone spot this lie?

The boldened part contains the lie. The researchers merely swapped the gene for the spike protein of SARS-CoV with that of a bat coronavirus (SCH014) and (surprisingly) it allowed the chimeric virus to infect human airway epithelial cells cultured in the study quite readily despite computer modelling suggesting otherwise. There was no enhancing of the SCH014 spike protein.


More importantly, this study raises the likelihood of a natural emergence of SARS-COV, because it clearly showed there were coronaviruses in the wild capable of infecting humans that existed more than 4 years before the Covid-19 pandemic.

Another falsehood (in bold) in the article is this:

MERS-CoV and some other distantly related coronaviruses have a polybasic furin cleavage site. The one in MERS-CoV allows it to invade human cells. Yes, MERS-CoV causes MERS, but SARS and MERS are really the same disease caused by different members of the same family, so in this sense MERS-CoV is a SARS-related betacoronavirus.


These factual errors in Wade’s article reduce his credibility and raise the likelihood of a natural emergence of SARS-COV-2. I wonder how many more errors we would find upon intensive fact-checking of his other claims.

PostScript: I found another paper on the furin cleavage site (FCS) and it appears the FCS is not necessary (but its a massive booster) for SARS-CoV-2 infection. This makes what Wade claimed below irrelevant since SARS-CoV-2 infection quite likely did not need a FCS to infect people early on as it crossed over into human populations:

And this part of his article (immediately following the above quote) more likely (if the virus had not evolved the binding site early on):


I think accusing the author of lying is unnecessarily uncharitable. What he’s saying is in my opinion inaccurate, but that could really just be a product of his own misunderstanding, or unavoidable linguistic and definitional ambiguities.

It seems to me what the researchers are doing isn’t to enhance the bat virus so as to infect humans, rather they took an already existing SARS virus infecting humans and gave it the bat-virus spike protein, to see if this bat-adapted spike protein could facilitate successful infection of human cells by the now modified SARS virus.
It’s rather philosophically muddled to argue whether taking the spike protein from a bat virus and replacing that on a human virus constitutes an enhancement, and similarly whether it’s an enhancement of the human or the bat virus. Does a bat-virus spike protein gene constitute a bat virus? Does putting that gene into a human virus and replace the corresponding one there enhance the virus, or turn it into a bit-virus?

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On another note, I found this talk*(also linked by Larry Moran) about the origin of SARS coronaviruses totally compelling:

You certainly aren’t the only statistician to have noticed those errors. Its likely some other statistician will expose any serious flaws in his Bayesian analysis.

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One thing seems certain; we haven’t heard the last of this.

CNBC: Biden orders closer review of Covid origins as U.S. intel weighs Wuhan lab leak theory.

He lied Rum, because he did not accurately present the aim of the researchers study, which was to test the “emergence potential” of a SARS-like bat coronavirus and not enhance its ability to infect humans.

First, they replaced SARS-CoV’s spike protein with that of SCH014 and the hybrid virus was able to infect human airway epithelial cells. Why did they do this?

Second, on seeing that the SCH014 spike protein expressed on the foreign SARS-CoV backbone was able to cause significant infections in the cell cultures and animals employed in the study, they tested to see if the SCH014 spike protein, this time in its native backbone would cause the same level of infection as observed when it was used in the SARS-CoV backbone. See what they found:

How can someone read that and still come off with the impression that the researchers tried to enhance the pathogenicity of any bat coronavirus in this study? A lot of people who won’t check or understand this paper would go away with the impression that it presents evidence that “Bat Lady” was designing viruses deadly to humans, which is just wrong.

In summary the paper says:

Wade lied. Simple.

His words were pretty clear. He claimed they enhanced the ability of other bat coronaviruses to attack humans, but that never happened.


With difficult talks looming ahead, here is an article explaining why the “lab leak” debate may very well make reaching a consensus for international good even more difficult.

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