Melanin
From Wigipedia, the free hair encyclopedia
Melanin is the pigment that gives hair, skin, and eyes their color. It is produced by specialized cells called melanocytes, and despite the enormous range of human coloring, it comes in only two basic varieties.[citation needed]
Just two pigments
- Eumelanin is the brown-to-black pigment. Lots of it gives black hair; less gives brown and blond.
- Pheomelanin is the red-to-yellow pigment.
Every natural hair color is just a ratio of these two. Red hair is heavy on pheomelanin and light on eumelanin, an effect strongly associated with variants in a gene called MC1R. Blond is a little eumelanin; black is a lot. There is no separate “blond pigment” or “red pigment factory” — it is all dosage and mixture.
When the pigment stops
Hair goes white when its melanocytes wind down and stop loading pigment into the growing strand. The hair itself is not painted white; it simply has no pigment left, and our eyes read unpigmented keratin as white. A head that looks gray is really a mix of pigmented and white hairs — the full story is in why hair turns gray.
Not just for looks
In skin, melanin does real work: it absorbs and scatters ultraviolet light, giving some protection against sun damage. The pigment in your hair is mostly cosmetic; the same pigment in your skin is quietly running a sunscreen operation.