I would take polar bears very, very seriously. They are ultimate predators.

Over 30 years ago, I took my kids to one of the old Ringling Bros. circus performances when they still had 3 rings. In one ring they had a spectacular bear act with a German or Czech guy and at least ten very large bears doing fairly modest tricks.

Grizzlies, browns, blacks -- all were in the cage and seemed fairly benign. Each was a big, fat specimen of its species.

Then they released an absolutely huge polar bear, must have been 10-foot tall. It did no tricks. The trainer left it strictly alone. Instead, it proceeded directly to the far end of the cage where an assistant fed it slices of bread through the bars throughout the performance. Then the trainer and other bears cleared out, after which the polar went back to its cage.

That made quite an impression on me.