It was noticed long ago that people from different parts of the world had different skin colors. For example, people who live near equator usually had darker skin than people who lived in colder regions.

When studied by scientists it was found that person’s skin color is determined by the amount of melanin in his or her skin. Every person has melanin in their skin but people who live where the sun shines all the year round have more melanin in their skins than people who live in colder areas.

Melanin is a dark brown pigment produced by special cells called Melanocytes. Melanin is essential to protect the skin from the ultra violet rays coming from the sun, which are harmful to skin and may cause skin cancer.

The areas that receive higher ultra violet radiation are generally located nearer to equator their lives darker-skinned population. Areas close to Noth or South poles have lower intensity of ultra violet radiation, their lives lighter-skinned population. Ultra violet rays coming from the sun is the main factor in determination of skin color. These rays are inclusive enough to penerate and burn light skin. The dark skin stops excessive sun rays at the skin to protect the healthy cells below skin. This is the reason of Negroes of Africa have dark skin while the people of Scandinavian countries (Sweden, Denmark, Norway) almost completely lack of melanin in their skins. In the northern areas, sun rays are weak and come from acute angle. So nature has withdrawn melanin so that cells of body receive some sunlight to produce vitamin D that body needs

In some northern coastal areas such as Alaska people have darker skin because they eat sea food, which provide all the vitamin D needed by the body, therefore their skin produces more melanin, which makes skin darker.