Questions tagged [hair]

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

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27
votes
3answers
270k 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 ...
23
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5answers
25k 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?
22
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1answer
6k views

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?
18
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4answers
7k 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 ...
16
votes
1answer
390k 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 ...
15
votes
2answers
154k 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 ...
11
votes
2answers
661 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 ...
10
votes
1answer
27k views

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 ...
9
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2answers
2k views

Did human hairs actually evolve from scales?

What is the evolution of hairs? Did they evolve from scales?
9
votes
1answer
9k views

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 ...
8
votes
1answer
108 views

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 ...
7
votes
1answer
4k 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 ...
6
votes
3answers
10k views

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.
6
votes
1answer
889 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
2k 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 ...
4
votes
1answer
2k 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 ...
4
votes
1answer
192 views

The onset of hair loss in men

I've seen men starting to lose hair in almost all ages. Why is the onset of hair loss in men different? Is there a normal distribution?
4
votes
2answers
717 views

Did baby bird hair and mammalian hair convergently evolve?

Chicks (baby of chickens) and ducklings seem to have fine hairs, at least something that look like hairs to me. Most mammals have hairs, but reptiles, fish, or other animal groups do not have hairs as ...
4
votes
0answers
203 views

Were Neandertals as Hairy as We Are?

What I mean to say regards facial and androgenic hairs. There are many theories as to why some people have both kinds of hairs, while others have one or the same and others still have neither. The ...
3
votes
1answer
581 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 ...
3
votes
1answer
65 views

Why do men have a greater chance of suffering from hair loss?

If we look around we'll find that men are more likely to suffer from hair loss when compared to women. Is there is any specific reason for this?
3
votes
0answers
39 views

Number of hair cycles in humans

I've seen several websites claim the amount of hair cycles a follicle will go through is predetermined at around 25-30 complete cycles. Is there any genetic evidence to validate this claim? How can ...
3
votes
1answer
485 views

Why do hair on head not get pilo-erected?

Whenever we have "goosebumps", there is a momentary piloerection, due to which hair on our elbows and legs get "erected" and "stand" almost perpendicular to the surface of our skin. But why do our "...
2
votes
2answers
2k 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
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2answers
4k 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
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2answers
2k 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
1answer
3k 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 ...
2
votes
1answer
1k views

Why does our hair turn white before we get old? [duplicate]

White hairs are considered a sign of old age, but they often occur in young boys. I want to ask why my hair is turning white? And why black hair turns white?
2
votes
1answer
105 views

Whitening of hair at old age [duplicate]

Human beings have evolved from their ancestors to their modern forms adapting many changes in structure and I would assume that every change has a significance. So, what is the cause of our hair ...
2
votes
1answer
880 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 ...
2
votes
1answer
144 views

Identify the fluff that I have found in tea

I have just opened a new pack of a black Pu'er tea that I've bought at the local store selling it by weight, and found a piece of fluff in there. To me it looks much like some kind of a bird fluff. It ...
2
votes
1answer
168 views

Why does the wavelength in curly hair differ?

Different people and animals have different wavelengths in the curls in their hair. I understand what purposes hair serves in protecting the skin from light and bugs. I am wondering about the eventual ...
2
votes
1answer
2k views

Why do some moles grow longer and darker hair than the rest of the skin?

In different parts of the body I have skin moles or in medical terms, nevus. In some of them hair grow seemingly either darker/thicker (I'm not sure how much of the two) and notably longer. Here are ...
1
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4answers
704 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
746 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
353 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
76 views

What is the evolutionary advantage of the Mane?

Horses, Donkeys, Antilopes and Bovines seem to have an evolutionary advantage in growing masses of hair on top (and sometimes below) the neck. Is that to hinder predators biting?
1
vote
0answers
50 views

Why are there sporadic lightly pigmented hairs in facial hair?

My body and scalp hair are entirely black. Until recently, I thought this was the case with my facial hair also, until I noticed a small handful of hairs that were anywhere from light brown to copper-...
1
vote
1answer
122 views

What is the biological/evolutionary advantage to baldness? [duplicate]

Male pattern baldness is a common genetic trait. With a distinctive pattern/ density gradent (as apposed to general old age thinning as the body ages) Hair has an advantage of protection from the sun/...
1
vote
0answers
44 views

Can hair follicle miniaturisation affect hair color?

We all know that follicle miniaturisation affects hair texture, making it look thinner(the hair shaft/root itself will be thinner), but does it affect hair color as well? So if an individual has thick ...
1
vote
0answers
73 views

Why does the scalp hair become grey first?

I understand that when the hair follicles produce less melanin or stop producing melanin altogether, hair becomes grey. But it seems like it is the scalp hair that becomes grey first. If follicles are ...
1
vote
0answers
54 views

Pigment returning to my grey [closed]

In the past I dyed my hair to cover the grey, but it became a more frequent event so I decided to just go grey. My hair has been almost entirely white for nearly 20 years. The pigment has been ...
1
vote
0answers
21 views

Why human hair is losing its color over time? [duplicate]

Human hair is losing its color over time, that's a known fact. I would like to know why, meaning what biological processes are involved in this? Also, is it part of the DNA somehow, i.e. the exact ...
1
vote
0answers
557 views

Why do some men have patchy beards?

Why do some men have patchy beards? Or more specifically, why would some hair follicles lack sufficient 5-alpha reductase while others nearby don't when their genetic code is identical and they are ...
1
vote
0answers
55 views

What determines the length to which hair grows? [duplicate]

Correct me if i am wrong, if we cut 2mm from eyebrow hair, it will grow 2mm and then stop growing, or if we cut 5mm, then it will grow only 5mm. My question is, does hair know how long to grow ?
1
vote
0answers
56 views

Would it be possible to create a gel, holding viruses, that could alter the human genome 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
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0answers
49 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 ...
1
vote
1answer
120 views

Do bald people not grow hair, or does their hair simply fall out immediately? [closed]

This image is not directly related but it made me wonder if there was a relationship between the nature of the hair follicle and baldness, namely that the follicle cannot 'hold' the continuously ...
0
votes
1answer
81 views

How large are the inner ear hairs?

I was always under the impression that the auditory hairs located deep within the ear, past the ear drum, are microscopic. After taking a shower today, I was softly padding my outer ear with some ...
0
votes
1answer
4k views

What does static electricity generated by plastic combs do to our hair?

It is said that wooden combs should be preferred to comb hair as compared to plastic combs. Reason is that plastic combs generate static electricity. Question: What does static electricity do to our ...