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Information about Gray Hair

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A white haired woman
Gray hair color typically occurs naturally as people age, usually turning their hair from its natural color to gray and then to white. More than 40 percent of Americans have some gray hair by their fortieth birthday, but white hairs can appear as early as childhood. The age at which graying begins seems to be almost entirely based on genetics. Sometimes people are born with gray hair because it is passed down genetically. Some people use hair dye to disguise the amount of gray in their hair.

The change in hair color is caused by the gradual decrease of pigmentation that occurs when melanin ceases to be produced in the hair root and new hairs grow in without pigment. Two genes appear to be responsible for the process of graying, Bcl2 and Mitf. The stem cells at the base of hair follicles are responsible for producing melanocytes, the cells that produce and store pigment in hair and skin. The death of the melanocyte stem cells causes the onset of graying.[1]

References

1. ^ Nishimura EK, Granter SR, Fisher DE (2005). "Mechanisms of hair graying: Incomplete melanocyte stem cell maintenance in the niche". Science 307 (5710): 720-4. PMID 15618488. 

See also

Genetics is the science of heredity and variation in living organisms.[1][2] Knowledge of the inheritance of characteristics has been implicitly used since prehistoric times for improving crop plants and animals through selective breeding.
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Hair coloring products generally fall into four categories: temporary, semipermanent, deposit only/demi, and permanent. All these hair color products, except for temporary color, suggest a patch test before application to determine if the client is allergic to the product.
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pigment is a material that changes the color of light it reflects as the result of selective color absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which the material itself emits light.
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Broadly, melanin is any of the polyacetylene, polyaniline, and polypyrrole "blacks" and "browns" or their mixed copolymers. The most common form of biological melanin is a polymer of either or both of two monomer molecules: indolequinone, and dihydroxyindole carboxylic acid.
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For a non-technical introduction to the topic, see .
A gene is a locatable region of genomic sequence, corresponding to a unit of inheritance, which is associated with regulatory regions, transcribed regions and/or other functional sequence regions.
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Stem cells are primal cells found in all multi-cellular organisms. They retain the ability to renew themselves through mitotic cell division and can differentiate into a diverse range of specialized cell types.
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Melanocytes are cells located in the bottom layer (the stratum basale) of the skin's epidermis and in the middle layer of the eye (the uvea).

Melanogenesis

Through a process called melanogenesis
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Science is the academic journal of the American Association for the Advancement of Science and is considered one of the world's most prestigious scientific journals. The journal is peer-reviewed, is published weekly, and has a print subscriber base of around 130,000.
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Hair is a filamentous outgrowth of protein, found only on mammals. It projects from the epidermis, though it grows from hair follicles deep in the dermis. Although many other organisms, especially insects, show filamentous outgrowths, these are not considered "hair".
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