US comedian Jon Stewart veered wildly off script during an appearance on The Late Show with Stephen Colbert this week, endorsing the theory that Covid-19 originated in a lab in Wuhan, China.
Despite the "lab leak theory" taking flight again in the US media, global scientists still point out there's little evidence that the virus came from a lab, but a large amount to suggest it came from nature.
"I think we owe a great debt of gratitude towards science. Science has in many ways helped ease the suffering of this pandemic, which was more than likely caused by science," Stewart began, which prompted a stunned reaction from Colbert.
The host asked his guest to elaborate: "So there's a chance this was created in a lab? If there's evidence, I'd love to hear it," he said.
"There's a chance?" Stewart scoffed. "Oh my God, there's a novel respiratory coronavirus overtaking China. What do we do? Oh, you know who we could ask? The Wuhan novel respiratory coronavirus lab. The disease is the same as the lab! That's just a little too weird, don't you think?"
Stewart was referring to the Wuhan Institute of Virology, a research institute around 15km from the seafood wet market that reported the first cluster of Covid cases late in 2019.
Stewart continued sarcastically: "You ask a scientist, 'So wait a minute, you work at the Wuhan respiratory coronavirus lab, how did this happen?' And they're like, 'hmmm, a pangolin kissed a turtle?' No! Look at the name of your lab! It's the coronavirus lab in Wuhan!"
He further mocked theories the virus jumped from animals to humans, saying: "Maybe a bat flew into the cloaca of a turkey and then it sneezed into my chilli and now we all have coronavirus."
In fact, there's a strong precedent for coronaviruses that have become "zoonotic", or jumped from animals to humans.
Scientists are aware of seven – including Sars-CoV and Mers-CoV – and bats are thought to have been involved in most of these.
Increasingly animated, Stewart stood up and banged the table as Colbert tried to calm his guest. But Stewart continued, comparing the origins of the pandemic to a theoretical "outbreak of chocolatey goodness near Hershey, Pennsylvania".
"Maybe a steam shovel mated with a cocoa bean … or it's the f***in' chocolate factory!"
Colbert countered: "It could be possible that they have the lab in Wuhan to study the novel coronavirus diseases because in Wuhan there are a lot of novel coronavirus diseases because of the bat population."
"Sure, and it's the only place to find bats," Stewart said sarcastically. "You won't find bats anywhere else! Oh wait, Austin, Texas has thousands of them that fly out of a cave every night at dusk. Is there an Austin coronavirus? No, there doesn't seem to be. The only coronavirus we have is in Wuhan, where they have – what's the lab called again, Stephen?"
Stewart's lengthy rant was met with a mixed response from viewers, with some criticising him – and indeed the show – for spreading misinformation and conspiracy theories.
Others worried his comments could stir up anti-Asian violence, already on the rise in America.
But various right-wing figures applauded Stewart for the speech. US senator Tom Cotton claimed Stewart was "right about the Wuhan lab – even if he's 18 months late".
Scientists do not say that the possibility of a lab leak should be entirely ruled out – many argue that it should be comprehensively investigated.
But more than a year after the outbreak, the weight of evidence overwhelmingly points to a natural source, while there's little to suggest the virus came from a lab.
Much of the recent coverage has been fuelled by a US intelligence report that stated several researchers had become sick with "symptoms consistent with Covid-19 and common seasonal illness".
A top director at the institute has rejected this inference, reporting that all staff have tested negative for Covid-19 antibodies, and that there'd been no turnover of staff in the coronavirus team.