I usually don't get around to trying to say anything intelligent about specific science topics, but I heard this story about skin color on NPR yesterday and was intrigued and comforted.
Professor Nina Jablonski, head of the Penn State Department of Anthropology, has some new work out suggesting that human skin color is an even quicker adaptation mechanism than people have thought before. She says that the melanin production, and thus skin color, of a family group can change in as little as 2000-2500 years. For a group of humans living near the equator without modern clothes and sundry other protective things, those with more pigmentation will have more protection against UV-induced damage, and thus they will have an advantage for survival and reproduction, carrying on their melanin-producing genes to future generations. Makes sense, people have been thinking that for a while now, right? BUT the cool part is that if that same group of humans migrates up more north, where now getting MORE UV is important for vitamin D production, they will gradually LOSE their pigmentation through the same selection mechanisms and be white as the whitest Scandinavian within only about 100 generations.
So, yes, there is a "genetic" basis to racial differences in skin tone, but that genetic basis lies equally inside all of us (except for maybe true albinos), and we all have the same potential inside to be black, white, brown or anywhere in between. It's a simple function of geography and biophysics of UV+skin, and nothing more. I think that is beautiful.