Evolution Vs. Adaptation

http://en.wikipedia.org/wiki/Natural_selection

Also, while the traits of Africans are the more dominant, they're not necessarily optimal to survival outside of Africa.
Different subspecies of humans evolved because their particular adaptations were more advantageous to survival in different climates, and in many cases throwbacks were weeded out by cultural selection until recessive were breeding with recessive until the theoretically more dominant genes were diluted out.

I've always assumed the genetic change to not be related to the living conditions, but I'll read through that anyway to see if it actually is.

The point I was trying to make is how exactly do traits get passed on genetically. Surely if you get exposed under the sun for a long time, that will tan your skin, but it will not necessarily alter the genetic information in your reproductive cells. I can see how exposure to high radiation can ionize the chemicals and make random changes to your body's building block (thus causing abnormal traits which can be passed on) and that has remained the only cell alteration method I know of.

From your post, I could get: People in a certain area remain dominant in population because their "adaptations" are more/most suitable to surviving in said area, which, if I recall correctly, is natural selection. This sounds much the same as the case of the peppered moths.
There was also the idea that people with recessive genes would be culturally forced to mate with one another and thus reducing/eliminating the population holding the recessive genes, but I'm half skeptical that I'm just seeing things on this one because it doesn't really make sense.

I guess in a nutshell, what I'm wondering is related to this article and the reverse idea of it. Adaptations can happen despite what the genetic information would suggest, and some adaptation are reflected back into the genes. But how?