How did the colour of the polar bears fur change from brown to white?

The color change in polar bear fur from brown to white is primarily a result of evolution and adaptation to their environment. As polar bears adapted to the Arctic habitat, lighter fur provided better camouflage against the ice and snow, aiding in hunting and survival. This coloration is due to the reflection of light off the hollow, transparent hairs, which appear white against the snowy backdrop. Over time, natural selection favored bears with lighter fur, leading to the predominance of this trait in the population.