Annoying Math Puzzle?

[pretty_cute_56]

Anwser this riddle:

A bear walks one mile due south, then one mile due east, and then one mile due north. He ends up at exactly the same spot where he started. What color is the bear? Give a rigorous proof.

[Brian]

the earth is round, so when it walks east, it is walking around the earth, then it goes south and ends up where it was

[maniac]

it is white because it is a polar bear.

the only way it could end up back where it has started by taking that course is if it lived in the north pole.

polar bears live in the north pole

[LeStefQc]

He started at the north pole and ended at the north pole. So he must be a polar bear making him white....