I just wanted to chime in on your comments about grizzlies at the time of settlement.

In California, until the introduction of firearms, the local tribes and grizzly bears were in a state of mutual predation. The early mountain men rather quickly shot them out. The last one in Cal was shot in the 1920s and now they are found only on the state flag. Grizzlies are truly a different kind of hazard from most other critters.

I was surprised, however, to check the Yellowstone website re grizzlies. They list only five visitor fatalities since 1916, which is rather surprising.