I found this article fascinating from the standpoint of how the tinest of mutations can result in amazing downstream results.
A couple quotes from the research:
"The work raises a raft of new questions -- not least of which is why white skin caught on so thoroughly in northern climes once it arose. Some scientists suggest that lighter skin offered a strong survival advantage for people who migrated out of Africa by boosting their levels of bone-strengthening vitamin D ... "
"Unlike most mutations, this one quickly overwhelmed its ancestral version, at least in Europe, suggesting it had a real benefit. Many scientists suspect that benefit has to do with vitamin D, made in the body with the help of sunlight and critical to proper bone development."