When bleck people become white

Europeans have had dark skin, until a 5500 years ago, claim Norwegian scientists. Our ancestors got the light skin when they change diet and from hunters became mostly farmers. The lack of meat and less sunlight in the northern parts caused shortage vitamuna D in the body, and dark skin pigments block UV rays, which allow his creation in body.
Scientists from the University of Oslo believe that a change in diet caused skin become whiter, to improve the creation of vitamin D. This thesis was confirmed studies by British Joanne Moen.
Recently, a study in the USA showed that half of African American hawe too low levels of vitamin D in the body.