WHair color is the pigmentation of hair follicles due to two types of melanin: eumelanin and pheomelanin. Generally, if more melanin is present, the color of the hair is darker; if less melanin is present, the hair is lighter. The tone of the hair is dependent on the ratio of black or brown eumelanin to yellow or red pheomelanin. 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. Some hair colors are associated with some ethnic groups due to observed higher frequency of particular hair color within their geographical region, e.g. straight dark hair amongst East Asians, a large variety of dark, light, curly, wavy and bushy hair amongst Europeans, curly, dark, and uniquely helical hair with Africans, whilst gray, white hair or "silver", is often associated with age and wisdom.
WAuburn hair is a variety of red hair, most commonly described as reddish-brown in color or dark ginger. Auburn hair ranges in shades from medium to dark. It can be found with a wide array of skin tones and eye colors. The chemical pigments that cause the coloration of auburn hair are frequently pheomelanin with high levels of eumelanin; however, the auburn hair is due to a mutated melanocortin 1 receptor gene in Northwestern European people and by a mutated TYRP1 gene in the Melanesians and Austronesians, both genes that reduce the melanin production of the hair cells.
WBlack hair is the darkest and most common of all human hair colors globally, due to larger populations with this dominant trait. It is a dominant genetic trait, and it is found in people of all backgrounds and ethnicities. It has large amounts of eumelanin and is more dense than other hair colors. In English, various types of black hair are sometimes described as soft-black, raven black, or jet-black. The range of skin colors associated with black hair is vast, ranging from the palest of light skin tones to dark skin. Black-haired humans can have dark or light eyes.
WBlond or fair hair, also blonde, is a hair color characterized by low levels of the dark pigment eumelanin. The resultant visible hue depends on various factors, but always has some yellowish color. The color can be from the very pale blond to reddish "strawberry" blond or golden-brownish ("sandy") blond colors. Occasionally, the state of being blond, and specifically the occurrence of blond traits in a predominantly dark or colored population are referred to as blondism.
WCongenital sensorineural deafness occurs commonly in domestic cats with a white coat. It is a congenital deafness caused by a degeneration of the inner ear. Deafness is far more common in white cats than in those with other coat colours. According to the ASPCA Complete Guide to Cats, "17 to 20 percent of white cats with nonblue eyes are deaf; 40 percent of "odd-eyed" white cats with one blue eye are deaf; and 65 to 85 percent of blue-eyed white cats are deaf."
WDip dye is a hair coloring style that involves dipping the ends of the hair into dye. The dye used can be either a naturally colored dye or a bright colored dye, the latter being the more popular choice.
WThe Fischer–Saller Scale, named for Nazi eugenicist Eugen Fischer and German anthropologist Karl Saller, is used in physical anthropology and medicine to determine the shades of hair color. The scale uses the following designations:
WMelanin is a broad term for a group of natural pigments found in most organisms. Melanin is produced through a multistage chemical process known as melanogenesis, where the oxidation of the amino acid tyrosine is followed by polymerization. The melanin pigments are produced in a specialized group of cells known as melanocytes.
WThe melanocortin 1 receptor (MC1R), also known as melanocyte-stimulating hormone receptor (MSHR), melanin-activating peptide receptor, or melanotropin receptor, is a G protein–coupled receptor that binds to a class of pituitary peptide hormones known as the melanocortins, which include adrenocorticotropic hormone (ACTH) and the different forms of melanocyte-stimulating hormone (MSH). It is coupled to Gαs and upregulates levels of cAMP by activating adenylyl cyclase in cells expressing this receptor. It is normally expressed in skin and melanocytes, and to a lesser degree in periaqueductal gray matter, astrocytes and leukocytes. In skin cancer, MC1R is highly expressed in melanomas but not carcinomas.
WRed hair occurs naturally in one to two percent of the human population, appearing with greater frequency among people of Northern or Northwestern European ancestry and lesser frequency in other populations. It is most common in individuals homozygous for a recessive allele on chromosome 16 that produces an altered version of the MC1R protein.
WTitian is a tint of red hair, most commonly described as brownish-orange in color. It is often confused with Venetian and auburn.