Hair is a biopolymer mostly made from keratin, which grows from the skin. Hair is exclusively found in mammals.
Questions tagged [hair]
79 questions
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Why can white hairs get dark again?
I have learned (probably in high school?) that hairs turning white is caused by the part of the folicle which produces the pigment dying and being replaced by an air bubble. This sounds very irreversible.
I have long dark brown hair, and since I…
rumtscho
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Do we know all the possible human hair colors?
I occasionally see people with blue hair and I always assume it is dyed. I wonder how justified is that assumption. Have biologists determined all the possible human hair colors? Or is it possible that if an embryo was exposed to the right amount of…
bimle
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Why does hair grow after trimming but remains at a constant length after a while?
Some hair especially body hair regrows after trimming but stops growing after a while. What is the mechanism behind control of hair growth and how is the length limit determined?
Mohini Yadav
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Why can hair grow without limit while eyebrow cannot?
I cut my eyebrow and it grows until reach a certain length. Hair can grow without limit.
Why can hair grow without limit while eyebrow cannot?
kiss my armpit
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What causes random long white body hairs?
I'm sure many of you have experienced this - you scratch your back or brush your hand over your arm and find a ridiculously long thin white hair, sometimes as long as 3 or 4 inches. I know a few people who get these quite frequently, and anecdotal…
Polynomial
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Why did humans lose their fur?
The little amount of body hair humans have don't seem to be of much use for keeping warm.
Our Simian cousins on the other hand sport thick furs.
At which point during the species evolution and why did humans lose their fur?
Cleber Goncalves
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What would cause red-haired people to become fewer?
There is this misconception that red-haired people are going to die out. This person on the Internet ("howstuffworks") also connected it to a marketing campaign of a hair dyer company. But I'm interested in a specific citation that he gives in that…
akraf
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What could cause hairs to gray at the tips but not the roots?
I have noticed that some of my sporadic gray hairs are gray at the tip side but oddly, not near the roots. Some are even only gray in the middle. I find all of this very counter intuitive, and I assure you nobody is secretly dying my hair.
How…
Jeff Axelrod
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Chiral (a)symmetry of curly hair (and fur)
Some people have curly hair, as well as fur of some animals can be curly.
However, shapes which are curly are not mirror symmetric, much alike screws or chiral molecules.
The question is whether curly hair in a given species (say, humans, but I…
Piotr Migdal
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How do disulphide bonds in hair cause curling?
I understand that there are several characteristics of curly hair which differ from straight hair (such as an asymmetrical distribution of disulphide bonds in curly hair), but really am struggling to understand the root cause of inherent curl on the…
User2341
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Did human hairs actually evolve from scales?
What is the evolution of hairs? Did they evolve from scales?
Anixx
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Do pulled hair from the root grow back?
There is not much to explain, I'm wondering if pulled hair, for example of the head, normally does grow back again or not. In reddit, It says this may depend on the follicle integrity, if the follicle is not hurt then it will grow back and…
Santropedro
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Why are bald heads so "shiny"?
Why do males with baldness have shiny skin on their head, whereas we don't experience such "shiny skin" in other parts of body without hair.
Failed Scientist
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Do individual mammal hairs absorb water?
In my look into the world of shaving I've seen claims that it is better to shave after a shower because the hairs will absorb water and soften, making the shave easier. Likewise, I've seen it claimed that natural hair brushes (i.e. boar and badger…
Sean Lake
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Why does hair turn white but not skin?
From my understanding melanocyte stem cells (McSCs) stop being produced and we have a finite reserve that gets depleted with time. They're at the origin of melanocytes that create hair and skin pigments. Our hair turns white when we don't have any…
ceillac
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