Sun Exposure and Skin Pigmentation
Although skin color is often categorized as black, red, yellow or white, nobody's skin is truly any of these colors. Our skin color lies somewhere on a continuum of shades from very dark brown to almost pink. Skin color changes throughout our lives because of sun exposure and other factors.
Researchers believe a clear correlation exists between where your ancestors lived and skin color. In sunnier, hotter climates, darker skin is more advantageous because it protects the body from UV rays. As people migrated to colder, less sunny environments, dark skin prevented enough vitamin D production, which in turn led to rickets and death. Lighter-skinned people were able to produce more vitamin D and live on to reproduce [source: Dreifus]. Darker-skinned people who now live in colder climates are still susceptible to rickets and, some scientists believe, other diseases because they are not getting enough vitamin D.
Deliberate sun exposure may lead to that evenly bronzed look common in celebrities, but it can also lead to a spray of freckles across the bridge of your nose or all over your face. It's no coincidence that redheads, typically bearers of the fairest skin of them all, are prone to freckles since their skin is very sensitive to the sun's rays.
Many people bask in the sunshine not to get vitamin D, but to get a tan. To read about the potential downsides of that so-called healthy glow, move on to the next page.