People come in many different shades. The various shades come from the earliest migrations out of Africa over 100,000 years ago. Humans, who started out with darker skin,  migrated to areas where the sun was less intense, causing their skin to eventually lighten, while the humans who stayed in Africa or migrated to areas where there was intense sun, had darker skin.

Why? Well, the sun produces ultraviolet (UV) lights, that have a great affect on the skin, either beneficial or damaging. When a person receives a moderate amount of UV, it is beneficial to the bones. However, if a person is exposed to too much, the skin can be damaged, wrinkled, it can cause aging, as well as skin cancer. The dark pigment in the skin is called melanin. The melanin is what helps block too much UV.

People in Africa are constantly exposed to the sun at an intense level, which means more melanin is required for them to survive. Those who traveled to colder climates, where the sun wasn’t as intense, loss a lot of melanin in order to better absorb Vitamin D.

Fast forward to years later, when Africans began to migrate to colder climates, their darker skin, which was originally there to protect them from the sun, made it difficult to absorb vitamin D. Which is the reason why today, many darker skin African Americans are Vitamin D, including my dad. However there are vitamin D pills that prevent the risky health issues that come along with being vitamin d deficient.

Source:

http://www.webmd.com/food-recipes/vitamin-d-deficiency

http://www.scientificamerican.com/article/vitamin-d-deficiency-united-states/

http://www.livescience.com/7863-people-white.html

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2671032/