"How often have I said to you that when you have eliminated the impossible, whatever remains, however improbable, must be the truth? We know that he did not come through the door, the window, or the chimney. We also know that he could not have been concealed in the room, as there is no concealment possible. When, then, did he come?" Sherlock Holmes in The Sign of Four, Arthur Conan Doyle, 1890
A storyline is “the qualitative and descriptive component of a scenario.” Storylines are commonly-used elements for thinking logically and systematically about plausible futures and plausible pasts. In the past week we all became familiar with the use of storylines in the search for the Titan submersible. As evidence accumulated an explanation for what happened evolved from multiple storylines that included the possibility of being stranded on the ocean floor, to bobbing lost on the ocean surface to a catastrophic implosion. Tragically, only the latter survived the accumulation of evidence.
Discussions of the origins of COVID-19 have been strong on theoretical and evidentiary claims (or lack thereof), but less so on storylines consistent with both theory and evidence. This holds especially for arguments for a market origin, and less so for a research-related origin. Both theories are judged plausible by U.S. intelligence and other agencies.
In 2021, Holmes and colleagues proposed a market origin storyline consistent with the evidence available at the time. You can see their summary of the storyline illustrated in their figure below.
This storyline posited that SARS-CoV-2 developed in animals that were caught and shipped to multiple wildlife markets in Wuhan, including the Huanan Seafood and Wildlife Market. They explain, “The multi-market aspect of the early outbreak can be explained by distribution of SARS-CoV-2 infected animals to more than one market.” This storyline is similar to what happened with SARS1.
However, subsequent analyses have overturned the idea that Covid-19 emerged in multiple markets across Wuhan. Instead, the current leading theory for a market origin centers on the Huanan Market.
One complexity of market-origin scenarios is that evidence points to two distinct lineages of SARS-CoV-2. Pekar and colleagues call this a “paradox” and develop a storyline to accommodate it (emphasis added in the below):
The genomic diversity of SARS-CoV-2 during the early pandemic presents a paradox. Lineage A viruses are at least two mutations closer to bat coronaviruses, indicating that the ancestor of SARS-CoV-2 arose from this lineage. However, lineage B viruses predominated early in the pandemic, particularly at the Huanan market, indicating that this lineage began spreading earlier in humans. Further complicating this matter is the molecular clock of SARS-CoV-2 in humans, which rejects a single-introduction origin of the pandemic from a lineage A virus. We resolved this paradox by showing that early SARS-CoV-2 genomic diversity and epidemiology are best explained by at least two separate zoonotic transmissions, in which lineage A and B progenitor viruses were both circulating in nonhuman mammals before their introduction into humans.
You can see their storyline illustrated in their schematic below.
Pekar and colleagues conclude that the B lineage of SARS-CoV-2 was introduced to humans on about 18 November 2019 and the A lineage on about 25 November 2019, in two independent events, both at the Haunan Market in Wuhan.
The dual spillover events obviously creates some complications for crafting a storyline consistent with the evidence. Here is what this theory would appear to imply in practical terms:
Multiple animals were infected with transmissible lineages of SARs-CoV-2;
The closest reservoirs of related bat corona viruses have been identified far from Wuhan, so an explanation is needed for how multiple animals are infected and how they find their way to a Wuhan market far from related coronavirus reservoirs and during a time of year when bats are inactive;
The infected animals necessarily were necessarily caught, caged, transported to the Huanan Market without infecting anyone else, or other animals, along the way (alternatively, they infected others, but all of these infections resulted in a dead end for further transmission);
The animals happened to both be brought to the Huanan Market, about one week apart, where they each independently initiated a transmission event that spread rapidly.
I may have missed something, so I welcome your thoughts.
Here is what I have yet to see: A storyline that can explain the four points above in practice.
One group of proponents of the double-spillover at the Huanan Market admit that there is no such storyline, yet still come to a firm conclusion on origin:
[T]here is insufficient evidence to define upstream events, and exact circumstances remain obscure, our analyses indicate that the emergence of SARS-CoV-2 occurred through the live wildlife trade in China and show that the Huanan market was the epicenter of the COVID-19 pandemic.
So here is my challenge to those proposing a Huanan Market origin for COVID-19 based on a double spillover: Create a storyline that can plausibly explain what happened, addressing the four points above. There may be multiple plausible storylines, such as when the Titan submersible first disappeared. Let’s hear them all.
Without such a storyline, a Huanan Market origin cannot stand on even terms with a scenario of a research-related accident, which is supported by multiple, plausible storylines. I’m happy to publish proposed storylines here, especially from those actively promoting the market-origin hypothesis.
Put your thinking caps on. Honest brokering is a group effort!
Please share this on your favorite social media, and especially the invitation to articulate a natural-origin storyline consistent with available evidence and theory. Your comments are welcomed, as usual. Please hit the little heart above and ReStack. Thanks for your support!
The first step to get good answers is to ask the right questions. I think you have done that very nicely in this post!
Last weekend’s Wagner mutiny is another example of using storylines to figure out what happened. Initially it was not clear if there was a coup or mutiny or simply nothing.
Some typos:
Is it the Hunan or Huanan market? You use the first spelling but the Pekar quote uses the second one.
By “25 November 2020” you probably meant 2019.
You should read the book "Viral" by Dr. Alina Chan, a postdoctoral researcher in medical genetics, synthetic biology and vector engineering at the Broad Institute of MIT and Harvard, and author Matt Ridley, who wrote the bestseller "Genome" and has written several articles in the Wall Street Journal and The Spectator about the origin and genomics of SARS CoV-2. During the pandemic, Dr. Chan conducted an extensive investigation of the possible origins of SARS CoV-2. The book makes a strong case for a lab release origin from the Wuhan Institute of Virology.