But the actual key to Covid’s origins has been there all along. According to Weiss, SARS-CoV and SARS-CoV-2 are more closely related to each other than either is to other human coronaviruses. But Weiss says both are also closer to related bat viruses than they are to each other. After more than a decade of research, it’s been established that the SARS-CoV originated in a bat and then moved, in the live-animal market of Guangdong in southern China, into intermediate hosts, civets, and likely raccoon dogs. Infecting other animals seems to disentangle, so to speak, a well-adapted bat virus from its original host, making it, for a time, something of a generalist, able to infect a range of species, including humans.

SARS-CoV-2 probably evolved in similar circumstances. It is likely that, again, civets, raccoon dogs, or other species acquired a bat-borne virus and spread it to other animals — and then to people: keepers, customers, passers-by in the 1,000-stall Huanan market, where wild animals of many different species were caged together in crowded, filthy conditions. These live animal markets are essentially disease factories, effective laboratories for the evolution of deadly pathogens. Huanan was soon shut down. No outsiders were permitted to examine it, or test workers for seroprevalence, which is, according to Goldstein, a critically important step.

According to the Chinese Academy of Engineering, as of 2016, the exotic food trade was a $19 billion industry in China, out of $76 billion for the overall wildlife industry. Countless live wild animals are sold for the luxury market each year. A lot of money is involved, and there’s a lot of incentive to keep quiet. Though the Huanan market remains shuttered and the wildlife trade for food banned, other markets, selling live animals such as chickens, ducks, and pigs, apparently remain open, and in regions far from the main centers trade in wildlife may continue. Live wild animals are also sold in markets throughout Asia.