Evolution's hall of shame.
The migration of animals, and polar flips.
Birds use the magnetic field, and land marks to migrate. Science says that on cloudy days, they totally rely on the earth's magnetic field. So if the fields are reversed, which direction will they fly on a cloudy day? In fact, which navigation technique do they rely on most (science cannot answer that one)? The reason I ask that question is: Which ever one is relied on most, will determine if they will survive, or die.
Other animals migrate, too. There are a few mammals, like some bats, caribou and elk, and whales that travel in search of food each winter. Many fish migrate. They may swim south, or move into deeper, warmer water.
