Why do people always bring up the eye example? It started with simple sensitivity to light and then progressively being able to make out more and more detail until you could clearly see. It probably would happen "fast" as being able to see clearly is generally a pretty huge advantage.And it's not like kangaroo pouches just slowly flipped around. If a sideways pouch was useless, there is no particular reason it would be passed down. Just looking at humans there are pretty vast physical mutations when cells don't split right early on (like extra limbs). Become a scientist and try and figure out how the pouch changed direction.Not being able to explain something is NOT proof against it.And a bear will always be a bear. Until it turns white and can catch food easier. Then maybe it migrates south and doesn't need it's hair at all anymore. So it loses it and so it can swim better. Then we have epic shark vs. bear battles.