BAD SCIENCE ON COVID IS STILL WITH US. You might think that, over the past year or two, public debate about the origins of the pandemic has loosened up. The lab-leak hypothesis has been aired repeatedly and endorsed with varying degrees of confidence by some intelligence agencies.

Even so, pandemic tribalism over whether the virus emerged from a laboratory or in a natural spillover at a market or elsewhere has proved remarkably resilient. Any shred of new evidence, no matter how flimsy, is hailed as near-definitive proof by one side or the other.

In mid-March, new analysis of genetic data collected in Wuhan's Huanan seafood market from January and February of 2020 generated enormous publicity for a scrap of virological news - and probably the most attention that's ever been given to an obscure, adorable species of mammal known as racoon dogs.

The short version is this : An international team of scientists discovered genetic material from the market that was previously held by Chinese scientists and, in analyzing it, found at least one sample that contained among other things scraped from the market, both racoon-dog DNA and SARS-Cob-2 viral material.

The analysis was notable, given the absence of hard evidence that an animal had been the source of the pandemic, the evasiveness of Chinese officials over what kinds of animals were in that market and the fact that racoon dogs had long been seen as potential intermediate host for the virus.

But it was also obviously limited evidence rather than a genetic smoking gun and suggested many follow-up questions. Was there any statistical correlation between the apparent presence of raccoon dogs in certain stalls and the presence of the virus in the same stalls?

Did such proximity really indicate an animal infection, or did it simply reflect the presence of SARS-Cov-2 throughout the market? And what could we infer from genetic material collected beginning in January 2020, when we knew already that there were human infections the previous month and possibly earlier?

But most commentary about the  new report was not nearly so circumspect. 

''The Strongest Evidence Yet. That an Animal Started the Pandemic,'' ran the headline of the first story to document the analysis.

In a few cases, scientists with public platforms urged caution in interpretation the data, but many others chimed in to describe the report as hugely consequential. For some, the presence of two sets of genetic material in the same sample was the mark of a raccoon-dog infection, and such an infection would be de facto proof of a natural origin of the pandemic.

Then, late last month, the computational biologist Jesse Bloom presented some persuasive evidence that everyone should perhaps calm down about racoon dogs. He uploaded a new preprint analysis of the same data - this time measuring not just the relative prevalence of animal genetic material but also the relative prevalence of SARS-CoV-2.

What he found was quite striking : In the same sample that contained the most raccoon dog genetic material, that contained any SARS. Cov-2 at all, the presence of the virus registered at only one sequence fragment in 200,000,000.

Overall, across the full database of genetic material found in the market, the presence of SARS-Cov-2 material : When samples had more raccoon-dog genetic material, there was actually less SARS-Cob-2 than was found in other samples.

''This definitely does not disprove that raccoon dogs could have been infected at some point,'' Mr. Bloom says. ''But it certainly says these samples don't provide any evidence of this.''

In fact, the presence of SARS-Cov-2 was much more closely associated with genetic material from other species, Mr. Bloom found, notably several kinds of fish and, to a lesser extent, humans.

The Master Essay Publishing and Opinion, continues. The World Students Society author David Wallace-Wells.


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