[count-your-change]

I trust I'm not taking too much of your time but you've raised a question here. If humans moving out of Africa had dark skin alleles whence came those light skin alleles to be selected as they moved out? Natural selection being selection, not creation, would a change of environment then be credited with the appearance of light skin alleles?

And if DNA reproduction (and its subsequent mixing in a small population) produces changes, even beneficial ones, might not this be the source of genetic novelty?

The vitamin D question is an interesting one. Are you suggesting vitamin D levels are related to degrees of skin pigmentation?

[allmendream]

Mutation of any dark skin allele will make it a light skin allele. In an African population this mutated allele will be selected against and in European populations this mutated allele will be selected for.

The environment selects for the change, it doesn't account for the change appearing, the environment ensures that those with the change will have a reproductive advantage.

Yes, DNA replication being error prone, introduces mutations into the human genome, thus being one of the sources of genetic variation/ genetic novelty.

Vitamin D levels are absolutely related to skin pigmentation. An African in Norway needs a vitamin D supplement or they will develop rickets. That is one reason they put Vitamin D in milk. Unfortunately, outside of a few cattle herding populations, most Africans are lactose intolerant and don't drink milk!