For well over a year we’ve been living through the devastating consequences of a highly transmissible coronavirus. While the pandemic it caused is unprecedented by many measures, the novel coronavirus that causes Covid-19 is just one of many SARS-related coronaviruses lurking among wildlife in some regions of the world, many of which could theoretically jump to human populations under the right conditions. Figuring out what those conditions are is an urgent priority, and scientists have made a lot of progress on that front. They’ve learned, for example, that when forests get fragmented by deforestation or roads, it increases the likelihood...