http://www.npr.org/templates/story/story.php?storyId=100057939
And that color, the one you have now, says Jablonski, is very probably not the color your ancient ancestors had -- even if you think your family has been the same color for a long, long time.
First off, I think this is fascinating. Recent discoveries in epigenetics are beginning to show us that we may have the capacity to evolve much more quickly than we've hypothesized. This article reminds me of a documentary I showed to my Intro class last semester (it's called "A Ghost in your Genes" and it's on youtube if you want to check it out) showing that environmental stimuli can actually trigger "switches" in our genes that can alter one's genetic code and in turn change what information we pass on to our children. For example, they found women who were in the vicinity of the 9/11 attacks during their third trimester had offspring that had significantly higher cortisol (stress hormone) levels when compared to children of women in earlier stages of pregnancy. Thus life events, especially those of significant impact or stress, can actually change what genes we pass on and accelerate the evolutionary process.
When applied to skin tone, I can see how a radical change of environment may invoke a need for adaptation and alter melanin levels over successive generations. It is also interesting when you consider the other article on a skin tone gene. People of different genetic backgrounds may have migrated to new regions and experienced a change in skin tone with less impact on other features. Although it's post hoc, this could be an explanation as to why Hispanics and Native Americans have similar skin tones but differ in other features (face structure, facial hair growth, etc.). Keeping this article in mind, it's also intriguing that skin tone is such a racial marker yet a person that we may label as an outgroup member today could have been similar to us in color generations ago.It makes me think twice about how we define group membership.