Why are there so many different skin pigmentations?

Even though we are all “out of Africa” there are numerous skin colors, because of how people have evolved differently in different regions of the world after the first migrations out of Africa. Scientists have related this back to two main hypotheses; sunscreen in the skin and vitamins.
Sunscreen in the skin which can also be referred to as melanin produces pigment in the skin. Scientists believe that before the first migrations we were all dark pigmented and had high concentrations of melanin in the skin. After migration patterns took people outside of Africa, a region close to the equator that receives large amounts of direct sunlight throughout the year, Homo sapiens no longer needed such high concentrations of melanin and could have possibly slowly lost the concentrations as the generations past until the skin had appropriate concentrations of melanin for the region the family was located.
The other hypothesis about different skin colors is humans’ intake of vitamin D. When UVB penetrates the skin it allows the skin to make vitamin D which is very useful to the body. Scientists have discovered that the world can almost perfectly be distributed into three vitamin D regions each with different levels of skin pigment degrees. It showed the farther away from the equator the less vitamin D a person could produce from UVB rays and the lighter the skin pigments were. There were exceptions which showed up when groups of people ate large amounts of vitamin D in their everyday diet such as the Inuit people in the far north. Which actually shows that vitamin D is actually very important to the differences in skin pigment.