Stuffed in a sports bag in Johannesburg, South Africa, the small pangolin was far from her natural environment. She’d been poached from her home and held without food or water for around 10 days, and now she was up for sale. In February 2020, wildlife traffickers brought her to an arranged meeting...

It began, almost certainly, in a bat. Then, just as SARS jumped to civets from bats, the virus that causes COVID-19 passed to another mammal, possibly a pangolin. Finally, late last year, the new coronavirus most likely jumped to humans in a wildlife market in Wuhan, China, a densely populated city...