Hair color

Hair color is the pigmentation of hair follicles due to two types of melanin: eumelanin and pheomelanin. Generally, if more eumelanin is present, the color of the hair is darker; if less eumelanin is present, the hair is lighter. The darker a person's natural hair color is, the more individual hair follicles they have on their scalp. Levels of melanin can vary over time causing a person's hair color to change, and it is possible to have hair follicles of more than one color on the same person. Particular hair colors are associated with ethnic groups. Gray or white hair is associated with age.

The Fischer–Saller scale, named after Eugen Fischer and Karl Saller (), is used in physical anthropology and medicine to determine the shades of hair color. The scale uses the following designations: A (very light blond), B to E (light blond), F to L (blond), M to O (dark blond), P to T (light brown to brown), U to Y (dark brown/black) and Roman numerals I to IV (red) and V to VI (red blond).

Two types of pigment give hair its color: eumelanin and pheomelanin. Pheomelanin colors hair orange and red. All humans have some pheomelanin in their hair. Eumelanin, which has two subtypes of black or brown, determines the darkness of the hair color. A low concentration of brown eumelanin results in blond hair, whereas a higher concentration of brown eumelanin results in brown hair. High amounts of black eumelanin result in black hair, while low concentrations result in gray hair.

...
Wikipedia