The difference between North and South

The genes for individuals that are not adapted for their environment will gradually be replaced by those that are better adapted. Red hair is an example of one of these adaptations.Red hair is an advantage in the northern climates,because the fair skin allowed ancestors to absorb more light and synthesize more vitamin D.
Thumbs up!However, this was a disadvantage in the more southern climates, where increased UV radiation led to cancer and decreased fertility. Thumbs down!