The bears were in dangerous proximity to humans: Hungry bears tore at open car windows. Yellowstone park rangers logged dozens of injuries each year—nearly 50 on average. Eventually, the Park Service ended the nightly landfill shows: Feeding wild animals human food wasn’t just dangerous, it was unnatural. The Yellowstone bears had been trained to rely on us. And so in 1975, the US Fish and Wildlife Service placed grizzly bears on the endangered species list, the country’s most powerful legal mechanism to stave off extinction.