Why do people have different color on the skin?

How come that natural selection has given man different colour of the skin in different parts of the world?
- It is because of the strength in solar radiation at different latitudes, in combination with what we originally have fed upon!

The reason why we even need the pigment (melanin) in the skin, is that it captures the sun's UV radiation. This protects our DNA and other molecules in the cells from damage.

Everything indicates that man in the beginning had much melanin and thus dark skin and that some groups of people have developed lighter skin as an adaptation to new environments.

The researchers believe that the key factor behind the fact that some parts of humanity are brighter than others, is our need of vitamin D. The useful form of vitamin D is abundant in the diet it is believed that hunter-gatherers ate . But people who mainly feed on cereals (like we do in Europe) may only get a precursor of vitamin D that needs to be converted to the actual vitamin D by UV-radiation from the sun. 

 

Since the dark pigment protects against UV light , a strong pigmented human who mainly eat cereal and live in an environment with little sunlight will get too little vitamin D.

It is believed therefore that farming people have been subjected to selection to push back the amount of melanin to exactly the level that makes it possible to produce enough vitamin D during the winter. As the sun declines with distance to the Equator have therefor grain-eating peoples become increasingly brighter , the farther from the equator they settled