Matt Ridley, Alina Chan

Eschewing speculation and sticking to what we could prove, we delved deep into the evidence and wove together the threads that linked bat viruses from southern China or Southeast Asia with an outbreak in Wuhan in late 2019. We concluded that it was impossible to be sure yet, but two theories were plausible: spillover from an animal to a person at a market, or an accident in a laboratory or during a research field trip.