Blonde hair and blue eyes are a sign of youth (aka beauty) in many areas far outside the north. Eyes and hair darken with age in many mammals. All kittens hav

Blonde hair and blue eyes are a sign of youth (aka beauty) in many areas far outside the north. Eyes and hair darken with age in many mammals. All kittens have blue eyes but virtually no cats retain them. Interestingly, the only mammal that regularly changes its eye color is the reindeer, a responce to the dark northern winters, although the mechanism is different than iris color.