Category: Hair biology
11 articles in this category.
- Alopecia — The medical umbrella term for hair loss — a word that, charmingly, comes from the Greek for 'fox.' It covers everything from ordinary pattern baldness to autoimmune patches to the hair you shed three months after a stressful summer.
- Androgenetic alopecia — Ordinary male- and female-pattern baldness, and the single most common cause of hair loss. It is driven by genetics and by the follicle's sensitivity to a hormone called DHT, which slowly shrinks hairs until they all but vanish.
- Do hair and nails grow after death? — The widely believed claim that hair and fingernails keep growing after a person dies. They do not — but they really do look like they do, and there's a tidy bit of physics behind the illusion.
- Goosebumps — The little bumps that rise on your skin in the cold or during a stirring song are tiny muscles trying to fluff up fur you no longer have. In humans they are a charming evolutionary leftover; in furrier animals they still do a real job.
- Keratin — The tough, stringy protein that hair, nails, horn, hooves, claws, and feathers are all made of. It is strong, water-shedding, and essentially indigestible — which explains a surprising amount of this encyclopedia.
- Melanin — The pigment that colors hair, skin, and eyes. There are only two kinds, and the mix of them — plus how much you make — accounts for nearly every natural hair color, from jet black to copper red to none at all.
- Rapunzel syndrome — A rare and genuinely alarming medical condition in which a person who eats their own hair grows a hairball in the stomach with a long tail trailing into the intestine — named, with grim wit, after the fairy-tale princess.
- Telogen effluvium — The alarming but usually harmless hair shedding that arrives a couple of months after a shock to the body — an illness, surgery, childbirth, crash diet, or major stress. It looks dramatic, and it almost always grows back.
- Whiskers (vibrissae) — Whiskers are not just fancy hairs — they are precision sensory instruments. Stiff, deeply wired, and arranged with surprising mathematical care, vibrissae let animals feel the shape of the world in the dark.
- Why hair turns gray — Gray hair is not really gray — it is a mix of pigmented and pigment-free strands, the result of color factories in the follicle quietly clocking out. And no, it cannot happen overnight, despite what they said about Marie Antoinette.
- World's longest hair — The record for the longest documented head of hair belongs to Xie Qiuping of China, whose hair reached 5.627 metres — about as long as a giraffe is tall. The secret is biology, patience, and an unusually long growth phase.