Human hair color

The hair color of a person depends on the amount of pigments, eumelanin and pheomelanin, which are contained in the fiber layer of the hair. Lack the pigments completely, the hairs are pale. This is the case in people with albinism.

Special hair colors

Brown

Red

Blond

Gray

Formation of the natural hair color of a person

The melanins are produced by melanocytes. It involves cells that sit in the hair follicles. They convert endogenous amino acids into various kinds of color pigment melanin, which provide the color palette for human hair.

Eumelanin is a black - brown pigment. It depends above all on how dark the color of the hair. In brown and black hair it is present in visible granules ( granules ).

The pheomelanin is a red - gold pigment. It is in light blonde, blond and red hair in larger quantities. This pigment is substantially smaller than eumelanin. The structure is also finer and more diffuse.

Depending on the mixing ratio of these two types of pigment caused the known human color variations. All shades of hair, such as brunette (French brunâtre = brownish, French brun = brown ), red-brown or auburn, resulting from different mixing ratios of the two types of melanin. The natural hair color of a person can be changed by means of hair dyeing.

Whether the hair color lights bright or matt appearance, does not depend on the color pigments, but from the colorless squamous cells ( cuticle ) of the hair surface. Standing on the scales of this layer, the color of the hair is dull and dull. Lying to the shed, the color lights bright. What color have the hair, whether they are straight or curly, thick or thin, and when the first gray hairs come, is genetically determined.

Distribution in human populations

More than half of all people have black hair, around three quarters of total are dark -haired. Black hair is genetically dominant and thus can be found in almost all human populations. Black is not the same black: So the hair of the Indo-Europeans is often of a very deep brown, while black Africans, East Asians and Indians mostly have deep black hair. In those parts of Europe with lightened hair color Black is mainly found in the descendants of the Celts in Ireland, England and Brittany.

The most common hair color of Europeans are in the range of brown tones that are out getting brighter deep brown in the Mediterranean to the north, where they are replaced by more blonde tones. Brown also frequently occurs among the aborigines of Australia, New Guinea and Melanesia.

Naturally blonde hair retain into adulthood only about 2% of the world population. They were originally most common in Northern and Eastern Europe (as well as by the European expansion in their descendants throughout the world ). In Southwest and Central Asia, and northwest Africa blonde hair occur locally. This is probably due to the contacts with northern Europeans since the Great Migration. In addition, blond hair comes - albeit mainly in children and women - often at the Aboriginal Central and eastern Australia before. Local occurrence of blond hair found in addition in New Guinea and Melanesia. Many legends tell of blond or red-haired Indians who had lived before Columbus in America. In fact, significantly lightened hair come before the people of the Mandan on the Missouri and the descendants of Chachapoyas in Peru. The cause may be due to either a mutation like the Melanesians or European influences before the colonial period. The latter is likely to be rejected by science.

A similar distribution have red hair. With 1-2 % of the world population, it is the rarest hair color. In Scotland, Wales and Ireland, it is most common. 13% of Scots have red hair. As you can see from the map, local occurrence of red hair are often to be found there, where blonde hair happen occasionally.

Gray human hair

Gray hair does not exist. The visual impression of the gray tuft comes from the mixture of pigmented and non-pigmented hair. It is either white or colorless.

Normally hair graying not suddenly, but slowly, step by step. The reason for the graying ( Canities ), is that the body produces in old age or because of certain diseases sufficient amounts of the amino acid tyrosine, which is essential for the production of melanin. The lack of melanin leads to hypopigmentation and is replaced by the incorporation of air bubbles into the hair shaft. Such hair appear white to the human eye.

On average, hair live three to seven years, then they fall out, and a new hair grows at this point. Gradually, the black, blond, brown or red hair are less and less, the white hairs for ever more. Hair at the temples have a shorter lifespan, just like whiskers. This is why most people turn gray here first.

A recent study showed that dying stem cells are the cause of graying. U.S. researchers demonstrated in animal experiments that hairs are white, if the number of certain stem cells decreases in the skin. These usually turn into melanocytes, which are responsible for the production of dyes in the hair, as reported by " Science Online" (12 /2004).

According to a study from the year 2009, the age-related deficiency of the enzyme catalase to cause the enzyme tyrosinase is inactivated by hydrogen peroxide and can no longer form melanin.

Cultural role of hair coloring

Hair coloring is detectable up to the time of ancient Egypt. The practice has always been accompanied by moral criticism, Fathers of the Church, she received an eschatological dimension. This changed only with the marketing technical optimization of hair coloring. The cosmetics industry succeeded after the discovery of advanced Haarfärbemethoden 1860, hair coloring, on the one hand to " naturalize " and on the other hand mythisieren in the context of blonde Hollywood stars. Among the outstanding media productions of hair coloring include Alfred Hitchcock's Vertigo (1958 ) and Jean Echenoz novel Les grandes blond (1995). Both show what mythical and life-changing power emanates from colored hair.