Naturalists who rode alligators and climbed trees barefoot into their seventies.

A country doctor famous for birds made two small cuts in his gardener's eight-year-old son — and then did it again, and again, for years.

A grizzly attack left him with a silver-dollar-sized hole in his skull — and that bear ended up on the California state flag.

He rode a caiman like a horse, built the world's first nature reserve, and accidentally set in motion the theory of evolution.

The zoo that once refused to hire him now sends its directors to the training academy he built.