evidence: Genetic evidence collected by Chinese researchers in January 2020—and finally made public earlier this year—puts raccoon dogs and other wild animals at a market in Wuhan, China, that was the epicenter of many of the earliest human COVID cases. That same evidence puts the COVID-causing virus, SARS-CoV-2, in many of those same market stalls. Experiments have shown raccoon dogs can be infected with and transmit SARS-CoV-2. Taken together, many scientists say, these findings point to a scenario in which the virus jumped to people at the market. But other researchers emphasize this is only circumstantial evidence—although they agree it warrants further investigation—and still leaves open the possibility of a "lab leak" as the start of the pandemic. [...] Bloom, however, points out that lab leak theories rely just as much on circumstantial evidence as natural origin theories do. The main argument for leaks, he says, is proximity-based: "The outbreak started in Wuhan, where there are labs that study SARS-like coronaviruses. There's definitely no direct evidence that any of the labs were studying a virus identical to SARS-CoV-2."