“Still, beyond these unforced errors, there are more zebras than physicians are often willing to admit. Perhaps the worst mistake a doctor can make is not their believing that they know everything but their acting as if everything is known. Today, millions of people live with poorly understood chronic illnesses—myalgic encephalomyelitis / chronic fatigue syndrome, autoimmune diseases, long COVID—that don’t fit cleanly into established categories or show up on tests in their early stages. Sifferlin quotes from the work of the anthropologist Abigail Dumes, who has argued that the rise of evidence-based medicine had the unintended effect of excluding these conditions from “the trappings of medical legibility.”