Human skin color ranges in variety from the darkest brown to the lightest pinkish-white hues. Human skin shows higher variation in color than any other single mammalian species and is the result of natural selection. Skin pigmentation in humans evolved to primarily regulate the amount of ultraviolet radiation penetrating the skin, controlling its biochemical effects.
The actual skin color of different humans is affected by many substances, although the single most important substance determining human skin color is the pigment melanin. Melanin is produced within the skin in cells called melanocytes and it is the main determinant of the skin color of darker-skinned humans. The skin color of people with light skin is determined mainly by the bluish-white connective tissue under the dermis and by the haemoglobin circulating in the veins of the dermis. The red color underlying the skin becomes more visible, especially in the face, when, as consequence of physical exercise or the stimulation of the nervous system (anger, fear), arterioles dilate.
Natural skin color can darken as a result of tanning due to exposure to sunlight. The leading theory is that skin color adapts to intense sunlight irradiation to provide partial protection against the ultraviolet fraction that produces damage and thus mutations in the DNA of the skin cells. There is a correlation between the geographic distribution of UV radiation (UVR) and the distribution of indigenous skin pigmentation around the world. Areas that highlight higher amounts of UVR reflect darker-skinned populations, generally located nearer towards the equator. Areas that are far from the tropics and closer to the poles have lower concentration of UVR, which is reflected in lighter-skinned populations.
Benini/bɨˈniːn/ (French: Bénin, formerly Dahomey), officially the Republic of Benin (French: République du Bénin), is a country in West Africa. It is bordered by Togo to the west, by Nigeria to the east and by Burkina Faso and Niger to the north. A majority of the population live on its small southern coastline on the Bight of Benin. The capital of Benin is Porto-Novo, but the seat of government is in Cotonou, the country's largest city. Benin covers an area of approximately 110,000 square kilometers (42,000 sq mi), with a population of approximately 9.05 million. Benin is a tropical, sub-Saharan nation, highly dependent on agriculture, with substantial employment and income arising from subsistence farming.