[ComfortEagle]

Exactly, Noah came from a region that is now inhabited by those of an olive-skinned color. Basically, over thousands of years people in those areas have adapted to their environments and climates to get the skin we have today.

Africans for example lack a certain chemical in their skin keeping them from getting sun burnt in the hot African sun, Caucasians have this chemical which reacts with the sun and is what causes our skin to burn.

According to Darwin's theories on natural selection, if a mutation occurs for the better it will be likely that this person will be more "fit" for the environment. Survival of the fittest. It is possible then, that Africans were once white and a mutation occured in someone that left out this chemical and as a result made their skin black. Since this would be an advantage in this area this person would survive and pass it on to his offspring, and so on.

Just a theory.