Human skin 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 (UVR) 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
Champagne gene The dun gene is responsible for flat, diluted coat colors and vivid primitive markings. Bay dun is thought to be the wildtype horse coat color. Dun does not affect skin or eye color, but dilutes red pigment to yellow and black pigment to slate gray. Champagne horses with the dun gene will have slightly further-diluted coats compared to non-dun champagnes, and will always exhibit striking primitive markings, such as a dorsal stripe and zebra-like stripes on the legs. The silver dapple gene in horses does not affect the eyes, skin, or red pigment. Chestnuts are unaffected, but in bay, seal