People whose ancestors lived for long periods in the regions of the globe near the equator generally have larger quantities of melanin in their skins, making their skins dark brown or black and protecting them against high levels of UV exposure. In areas of the globe closer to the poles, people have far less need for protection from ultraviolet, so their skin is usually lighter in colour. This allows sunlight to stimulate vitamin D production.
Freckles and moless are formed where there is a greater concentration of melanin in the skin.
See also human skin color