The are number of theories that attempt to explain why there are'difference in skin color. One theory holds that lighter skin evolved as an adaption to weaker sunlight and the need to extract more sunlight to manufacture Vitamin D. Pale skin makes this easier when the sun's rays are not particularly strong. But unfortunately for people with pale skin malignant melanoma, the'deadliest form of skin cancer, is more common among lighter skinned people than darker skinned ones.