This questions came to me after some discussion on my previous one about a civilization living under Antarctica.
I somehow have the feeling this is a dumb question - sorry if it is -, however I can't figure out what the answer would be...
If a human population whose members are black-skinned came to live underground for generations, would they become paler and paler or would they stay black ?
What I know :
The reason why cave creatures are mostly white or extremely pale is because skin pigmentation is a process that takes energy to the body to achieve and therefore in the absence of light, it would be a waste of energy.
Natural selection keeps the best genetic options to help animals and humans survive in their environment. I know the process and how it works ( the strongest survive longer and then can have more descendants ; dominant / recessive genes ; etc). However in this case, I can't figure out if natural selection would "chose" dark or light skin.
What I wonder about :
Wouldn't natural selection in this case prevent those people from whitening ? I mean, in caves with low light, it is easier to hide (whether for escaping or hunting a creature) when you have dark skin. So would the ones with a darker skin survive easier ?
Would there be a natural selection process at all considering this is a united and organized population where the weakest are helped by the strongest ? Also would having a black skin (in the case where white skin would be better for survival) be a sufficiently "dangerous" characteristic to provoke enough death to trigger natural selection on the concerned genes ?
Speaking of evolution, could it possibly make new generations whiter, despite all members of this population are black-skinned and then have this characteristic in their genes ?
If this process of whitening was to happen, how much time would it take ? I assume it would take longer than other human mutations because of the transition from very dark skin to very pale, but I hardly can put a time scale on it.
I know these are a lot of interrogation but I think they are all important points to consider in order to answer the question
Thanks in advance for your answers :)