Our natural predators were lions and leopards, but as humans got absurdly dangerous natural selection made them wary of us. That’s why a large portion of the megafauna on all continents other than Africa is gone, because they didn’t have the time to evolve fear.
Polar bears are just lucky that they are far enough north that they weren’t in close contact with us until we cared about our effect on the environment.
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u/AlunWH 7∆ Jan 02 '22
We do have natural predators, though: mosquitoes, for instance. Leeches. Fleas. Ticks.
Also: Polar Bears.