Why the different skin colors and traits

If we all started from the black skin color, then why develop different skin colors and traits? I would assume that according to heat and the amount of sun each area receives, but then why pale (caucasian)? What reasons could there be for a development of a pale skin color, which doesn't seem to have any advantages. So why develop different skin colors? Also, not being racist, but look at the traits themselves. Black people have thicker lips and different hair than asians, who have different, thinner hair, shorter stature, and almond-shaped eyes (generally speaking). And then there are white people who have layered hair, odd circular eyes (again, generally), thinner lips, and more body hair. There are more than that, but it is late, and I am tired. So why the differences?

Skin tone depends on how much melanin (light absorbing pigment) is in the skin. We evolved in the hot and sunny African savanna about 150,000 years ago, and we needed as much melanin as possible to protect us against sun burn and skin cancer. Since there is so much sun, we can have enough UV light to synthesize vitamin D, even with a dark skin. About 60,000-80,000 years ago, human beings began migrating out of Africa. The first place we ended up was Asia and Australia. The climate there is still pretty tropical, so we see many Indians, Negritos, and Australian aborigines still having dark skin. A later wave of migrants went to Central Asia and China. The Central Asian steppes and northern China are farther away from the Equator, so there is less sunlight during winter. In order to absorb enough UV light, skin tones start to lighten among people in northern China. The Central Asians stayed there for about 20,000 years before they were finally well adapted enough to cold climates to invade Europe, which was at the time occupied by Neanderthals, who were superbly adapted to cold weather.

After Cro-Magnon man invaded Europe, the Neanderthals became extinct. The first Europeans expanded their range throughout Europe. There they evolved lighter skin tones because of the same reason that people from northern China and Korea did: to absorb enough UV light to synthesize vitamin D (in fact, a recent study suggests that American kids do not stay outdoors often enough to synthesize vitamin D, which is vital for strong bones and teeth). It turns out that many Europeans with red hair have more pheomelanin in their body than other people. Pheomelanin is what gives red hair its color. Red haired people tend to have lighter skin tones, because pheomelanin is not as dark as eumelanin. Albino Africans also tend to have blond hair and light skin, just like blond Europeans, although their facial features are different.