Wild animals have always had viruses coursing through their bodies. But a global wildlife trade worth billions of dollars, agricultural intensification, deforestation and urbanization are bringing people closer to animals, giving their viruses more of what they need to infect us: opportunity. Most fail. Some succeed on small scales. Very few, like SARS-CoV-2, the novel coronavirus, triumph, aided by a supremely interconnected human population that can transport a pathogen around the world on a jet in mere hours.