Bite-size origin science
Less than 5 minutes to explain a scientific consensus
Asymmetric factors of our broken info sphere favor intuitive, emotional and exciting myths over dry, nuanced and complicated science. Fantasies, fears and lies about bioweapons, secret experiments and cover-up conspiracies travel five times around the world before truth has a chance to get the boots on. That’s the attention economy, and reality barely has time to get a word in.
The question is rather simple: What does science know about where SARS-CoV-2 came from?
So here I outlined nine different, but mutually compatible and internally consistent, lines of evidence that point towards a zoonotic origin of SARS-CoV-2 and are representative of the broader scientific literature on the topic. Each line of evidence is either contradicting, debunking or severely limiting the possibility space for any and all research-related origins of Covid-19.
So here is the bite-size version:
1) Case Epidemiology
Hospitalizations and cases clustered around the Huanan market in Wuhan (WHO report, 2021), both for epidemiologically linked and unlinked cases for the market (Worobey M, Science, 2021). That market link holds even when controlled for population density, age and ascertainment bias (Worobey et al., Science, 2022)
2) Natural genome
The SARS-CoV-2 genome shows many hallmarks of natural evolution, and no signs of genetic engineering or other manipulations (Anderson et al, Nature medicine, 2020 & Holmes et al., Cell, 2021 & Garry R, PNAS, 2022)
3) Multiple introductions
A single spillover (e.g from a lab leak) would die out 70% of the time by itself. (Pekar et al., Science, 2021) Case history and simulations, phylogenetic clock and polytomies point to at least 2 separate successful introductions, and up to 15 total (Pekar et al, Science, 2022)
4) Two original lineages
Phylogenetic analysis showed that there were two separate lineages (Rambaut et al, Nature Microbiology, 2020) from the start of the outbreak, polytomies & lack of transitional genomes are indicating multiple introductions from an animal population (Pekar et al., Science, 2022)
5) Hotspots
Bats & other animals carrying SC2r viruses have a wide range and are found in China (Zhou et al, Cell, 2021), Laos, Thailand (Wacharapluesadee et al, Nature communications, 2021) and other countries in South East Asia. Models suggest >60.000 CoV spillovers per year (Sanchez et al, Nature Communication, 2021)
6) Outbreak site
All early cases cluster around a poorly visited market, a place unlikely to facilitate an human-to-human outbreak compared to restaurants, churches, stadiums that have been observed as amplifying events after introduction of SC2 in other cities (Worobey et al., Science, 2022). The market is also far away from the Wuhan Institute of Virology on the other side of the Yangtze river (Holmes et al, Cell, 2021)
7) History
Zoonotic coronaviruses are common and have caused pandemics before (Cui et al., Nature Reviews Microbiology, 2018). SC2 shows many parallels to SARS-1 outbreak, including wildlife trade, time of year and Hubei farms link (Shi et al., Virus Research, 2007). All previous pandemics with an unknown pathogen were caused by zoonotic spillovers, which are common and present danger (Keusch et al, PNAS, 2022)
8) Animals at market
Investigations have shown that many SC2 susceptible animals had been sold at the Huanan market up until December 2019. (Xiao et al, Sci Reports, 2021 & Worobey et al., Science, 2022) Environmental samples cluster around shops where live animals were sold.
9) Recombination
The genome of SARS-CoV-2 is like a jigsaw puzzle with 27 pieces. All elements of its genome are found in nature (Zhou et al., Cell, 2021 & Temman et al., Nature, 2022) and the virus could have only come about through recombination in nature (on top of normal evolution & selection mechanism) (Lytras et al., Genome Biol Evol. 2022)
(for a longer explanation, you can also read this)
Important before you go:
Each scientific reference listed here is also build upon the work of hundreds of independent scientists and connected to a tree of knowledge about emerging diseases, virology, phylogenetic methods, bat ecology, animal surveillance, laboratory techniques, epidemiology, previously published research and much more that would break the space to list here in full. It is called “body of scientific knowledge” for a reason, and I just outlined some key backbones above.
The interested reader is advised to check out the scientific references as a starting point to gain a deeper knowledge about the detailed literature to get a full appreciation of how detailed and strong the evidence for a zoonotic origin actually is (and why there is a scientific consensus on the topic).
The science is clear, lableak is dead. But the conspiracy myth will likely never die.
