The standard story about animal viruses jumping to humans usually goes something like this. A virus hangs out in bats or pigs, picks up mutations over time, and eventually becomes human-ready. Then it spills over, and we get a pandemic. Nice story. But the genomic data doesnt always cooperate. A 2026 study from UC San Diego, Temple University, and a few other labs dug into the evolutionary fingerprints of the most consequential viruses from the last twenty years. They came back with findings that upend a lot of the conventional wisdom. The Two Models So heres the core question: do animal viruses actually need to adapt to humans before triggering…