Mondo Knows Facts
Hair turns grey as pigment cells dwindle
Melanocyte stem cells in the follicle run down, so new hair grows unpigmented Each hair follicle keeps a small reservoir of melanocyte stem cells that supply pigment to the growing shaft. Over many hair cycles these cells become exhausted or fail to mature. The hair then grows without melanin, and the mix of pigmented and unpigmented strands reads as grey. It sits in Mondo's human body collection, one of 200 facts that each trace back to the reference below.
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Facts that can change over time are reviewed and updated. If something here looks wrong, Mondo would rather know than be confidently incorrect.
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More facts like this
Melanin determines skin hair and eye colourationSpecialised melanocyte cells produce pigments that absorb ultraviolet radiationHuman scalp hair grows at about one centimetre per monthHair follicles cycle through growth rest and shedding phases continuouslyHair and fingernails are composed of the protein keratinTough structural proteins form non-living outer protective structuresFine fetal hair called lanugo is shed before birthA downy coat covers the fetus from about twenty weeks and mostly disappears by termMuscle mass falls steadily from middle ageAfter about thirty, adults lose a small percentage of muscle each decadeSkin loses collagen and elasticity with ageCollagen production in the dermis falls while existing fibres become fragmented
🫀 Human Bodyfact 189 of 200
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Tags: hair, ageing, melanin
Hair turns grey as pigment cells dwindle: the short answers
- Where does this come from, and can I check it?
- Melanocyte stem cells in the follicle run down, so new hair grows unpigmented. The figure is taken from NIEHS, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.
- Is this really a human body fact?
- Yes. It sits on the Human Body shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.
- What else can I read about it?
- The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.