Experts disagree. Here’s why:
Some think the virus might have hidden in rodents or other animals, rather than people, and therefore experienced different evolutionary pressures that selected for novel mutations. “The genome is just so weird,” says Kristian Andersen, an infectious disease researcher at Scripps Research, pointing to its medley of mutations, many of which have not been seen before in other variants.
“It is interesting, just how crazily different it is,” says evolutionary biologist Mike Worobey of the University of Arizona, Tucson. Although he favors an immunosuppressed person as the source of Omicron, Worobey notes that 80% of white-tailed deer sampled in Iowa between late November 2020 and early January 2021 carried SARS-CoV-2, according to a recent preprint. “It does make me wonder if other species out there can become chronically infected, which would potentially provide this sort of selective pressure over time.”Kai Kupferschmidt, “Where did ‘weird’ Omicron come from?” at Science (Where did ‘weird’ Omicron come from?)
It’s too early, we are told, to rule anything out.
Thought: Maybe lots of viruses are weird but we don’t pay much attention to most of them.