This is because melanin protects the skin from damage caused by the sun's ultraviolet (UV) radiation. In regions closer to the equator, where the sun is stronger and more direct, darker skin with more melanin is advantageous in preventing skin cancer, sunburn, and other skin damage. However, as populations migrated away from the equator to regions with less intense sunlight, lighter skin with less melanin became more advantageous in allowing the skin to absorb vitamin D from the sun more efficiently. This is why people with lighter skin are more commonly found in regions with less sunlight, such as Northern Europe, while people with darker skin are more commonly found in regions with more sunlight, such as Africa.
