Black skin:
Black skin is sporadically found in tropical regions. It roughly corresponds to a Luschan scale of 30-36 and sometimes shows a blueish tint. It is relatively rare in the central tropics, where humid climate and many clouds offer some protection against the sun. Instead, it is found in dry savannahs, where the sun burns throughout the day. The most populous black-skinned group are the Nilotes of African savannahs, but it also occurs in several Sudanid groups, especially around Senegal, in Mountain Dama, and a few Bantu groups. Outside of Africa, Andamanese, some Melanesians (e.g. in the Western Solomons and Bougainville), a few North Australians, and South Indians may show black skin. Black skin offers the best protection again strong solar radiation, sunburn hardly occurs. The strong pigmentation often alters the colour of the lips and eye sclera as well.