Central European wild boars remain persistently radioactive because winter foraging drives them to excavate underground deer truffles (*Elaphomyces*), which slowly accumulated downward-migrating cesium-137 from 1960s atmospheric nuclear weapons tests. Isotopic ratio analysis demonstrates that up to 68% of their contamination stems from Cold War weapons testing fallout rather than Chernobyl, explaining why boar contamination persisted decades after surface-foraging wildlife cleared. nautil.us