Hair is a biopolymer mostly made from keratin, which grows from the skin. Hair is exclusively found in mammals.

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17
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3answers
22k views

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 ...
13
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3answers
2k views

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?
11
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1answer
102k views

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 ...
9
votes
2answers
344 views

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 ...
6
votes
1answer
679 views

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 ...
6
votes
2answers
20k views

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 ...
5
votes
1answer
102 views

Does gray/white hair turn gray/white from a normal hair? or does a gray/white hair actually grow gray/white originally?

I am really curious if hair actually tuns white/gray from default color, or does it have a defect as it is made and grows out of your head a different color?
5
votes
1answer
237 views

Why does hair thicken and become more rough after a razor shave but not after one using a trimmer? [closed]

If a razor cuts only the hair, then how does hair thicken and become more rough with a razor shave and not after one using a trimmer? If both are used for hair removal, why is there a difference in ...
4
votes
1answer
150 views

Redheads and pain receptors

I remember reading this in a biology textbook, and decided to do a little digging. Redheads have a lower sensitivity to some pain and a higher sensitivity to other compared to people of other colored ...
3
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1answer
479 views

What hair color will result in someone inheriting both blond and ginger genes?

Both the genes for blond hair and ginger hair are recessive, so they need both parents to give the same gene for it to take affect. What happens when a person has 1 copy of a recessive gene and ...
3
votes
1answer
101 views

What is the use of shampoo; is it for the hair or for the scalp?

Apologies for the confusing question; I did not know how to better ask it. I was doing a search on wikipedia when I found this statement. Wikipedia's entry on hair states; "The hair that is ...
2
votes
2answers
649 views

Iron deficiency anemia symptoms explanation

In my classes and on the internet, brittle nails and dry hair (or hair loss) are described as symptoms of iron deficiency anemia, but none explains the cause of such symptoms. Does anyone have any ...
2
votes
2answers
160 views

Are there free electrons in muscles, hair, or skin?

Electric shock occurs upon contact of a (human) body part with any source of electricity that causes a sufficient current through the skin, muscles, or hair. In metals many electrons are said to be ...
2
votes
2answers
155 views

Is there a medical condition in which you can't cut your hair?

Just curious, does there exist a medical condition in which a patient is advised not to or simply cannot cut their (head) hair?
2
votes
1answer
198 views

What is the chemical process involved in human hairs changing colour after sun exposure?

After a day at the beach, my skin tans due to Melanin. But I also observe the black hairs on my arm turn a blond colour. My question is What is the chemical process involved in human hairs ...
1
vote
4answers
185 views

Significance of having goosebumps?

What help does goosebumps do to us? I don't think it helps us noticeably when we are scared or shivering.
1
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1answer
76 views

DNA extraction methods for hair?

TLDR: Can anyone state a extraction and isolation method(s) for genomic DNA for hair that will be used for PCR, in detail is preferable since I am a novice. I tried googling for DNA extraction ...
1
vote
1answer
118 views

Why would the Camargue horses have a white coat while the foal have a dark coat?

The current issue of the magazine Lonely Planet India(Oct 2013) presents a photo of Camargue Horses which are white coated and mentions that they are born with dark hair. A search shows that the foal ...
1
vote
1answer
371 views

How does hair grow and is it similar to how grass grows?

If I recall correctly, nails (finger nails or toe nails) grow by adding matter at its base. So for instance, if you would draw a dot at the very bottom of your nail, it would end at the top in a ...
1
vote
1answer
448 views

Approximately how thick is a single strand of cat (domestic housecat) hair?

I did a little research to lead me to finding the general range of width for human hair, which is anywhere from around 30µm to 180µm... approximately. I'm trying to compare this to the width of cat ...
1
vote
0answers
43 views

Would it be possible to create a gel, holding viruses, that could alter human genetic code when rubbed in?

I was wondering if it could be possible to engineer a virus, that when it comes into contact with human hair follicles, it could alter someones natural hair color. Naturally blue hair anyone? ...
1
vote
0answers
18 views

Does the use of a Thiazide diuretic affect the ability of a hair follicle to absorb substances?

Thiazide diuretics are on the World Anti Doping Agency's, as well as the International Olympic Committee, list of banned substances due to it ability to mask illegal substances in urine. The rapid ...
0
votes
1answer
45 views

Do hairs in the ear respond to things like shampoo?

Shampoo and conditioning products make claims to be the end all be all in hair care. I doubt that they are so advanced "growth formula/anti-breakage/oily treatment". Have any of the claims been shown ...
0
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1answer
49 views

Safe level of chlorine in water [closed]

Chlorine is usually mixed in water to make it safe for consumption. What is a safe quantity of chlorine that can be consumed? What are the side effects of chlorine and does this include hair loss? ...
0
votes
1answer
40 views

How do cats shed their fur?

Dogs shed their fur twice a year, so I assume this is the same with cats. What is the mechanism whereby the change in temperature (assuming this is what causes the shedding) leads to the falling off ...
0
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0answers
31 views

Why do human have continuously-growing hair on their head? [duplicate]

Why do hair continuously grow on human heads, while the same doesn't happen on other parts of the human body? Where there are hair, they only usually grow to a fixed length; but they seem to have no ...
0
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0answers
49 views

If what we eat can be seen in our hair, then to what degree can our food affect the “look and feel” of our hair?

It looks like most things (or everything?) that we consume, whether it is a food, drink, or something we smoke (like e.g. some drug like marijuana) ends up in some amounts in our hair. If this is the ...
0
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0answers
53 views

Why do we have butt hair? [duplicate]

Why do we have hair on our butts? From what I understand, hair is generally used for warmth, but it seems like our buttox would be one of the last places on our body that would need warmth. Moreover, ...