Science Questions

Why Have Pubic Hair

Sun, 28th Oct 2007

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Question

John, Hong Kong asked:

My question is about pubic hair. Some people have said its purpose is to protect your bits, or to keep your bits warm, or to make you smell more attractive to the opposite sex. I want to know why to humans have it, do other animals have it, and what is its main function?

Answer

We asked Christophe Soligo from University College London to help with this question...

Underarm HairI think a good indication of why we have pubic hair comes from the distribution of sweat glands that humans have.  We essentially have two types of sweat glands; ones which are called eccrine glands, which are distributed across the whole of the body and they’re the sweat glands which we use for keeping cool.  On top of these we also have a second type of sweat glands which are called apocrine glands.  The distribution of apocrine glands essentially coincides with the distribution of pubic and also axillary hair in the armpit, and the secretion from apocrine glands also contains small parts of cellular material.  The cellular material gets broken down by bacteria and that’s what creates to a large extent our personal body odour.  So the secretion from sweat glands together with the location and the hair creates a nice damp substrate for growth for bacteria.

The next step is a bit more complicated than just to smell more attractive to the opposite sex.  Some research that’s been done where men were made to wear the same t-shirt for several nights running, and women were made to smell the t-shirts after and to rank them according to how attractive they found the smell.  The result was that women seem to be able to detect genetic differences in the men, specifically in a genetic complex we call the Major Histocompatability Complex (MHC).  What’s interesting there is that women were actually going for the men whose MHC composition was the most different to their own.  That makes sense in the context of fighting disease because if you have offspring with a very variable MHC it increases their ability to fight off disease.

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I would guess that they are a left over from when we were covered in hair, but what purpose does it now serve?

I think this may have been answered by Rosy in another topic, when she states:



So i say, that pubic hair acts as a sort of wick to release pheromones.

If this is correct, does Rosy get a prize? If she does then i think she should really donate it to me as there may be a conflict of interest!  paul.fr, Wed, 24th Oct 2007

I am an expert on pubic hair. When I began conducting research into Inclined Bed Therapy we noticed, actually a nurse taking part in the primary study noticed that her pubic hair was no longer the preverbial short and curlies but continued to grow and became less course than before. Great I said sheepishly, thinking now this I gotta check out for myself as I was also sleeping on an inclined bed and so was my very understanding lab rat and darling wife Jude.
Sure enough my own pubes had to be cut off as they no longer fall out as they had done previously. We also noticed not much hair in the bathwater either. Fascinating, bacause my research was all about maintaining the circualtion while we sleep by tilting the head of the bed by six inches or fifteen cm's providing a level but tilted mattress avoiding flat bed rest since 1994. There have been many more observations using the same principle which have been discussed at length on the Naked Scientists forum. I have mentioned this several times before http://www.thenakedscientists.com/forum/index.php?topic=10224.0

Andrew K Fletcher Andrew K Fletcher, Wed, 24th Oct 2007

I've noticed during summer when i wear shorts the hairs on my legs get thicker and longer in certain places. This is due to their being less friction from jeans, trousers etc rubbing on my legs eroding and breaking the hairs off. So maybe pubic hair is so thick as they are in a place with low friction ,plus the need for the body to keep certain parts warm. ukmicky, Wed, 24th Oct 2007

ok whats the big idea? nobody contributes until i ,in passing, mention a prize!..it' mine i tell y'...all mine...rubs hands with big smile on face paul.fr, Thu, 25th Oct 2007

I'm always amazed at the preoccupation with removing pubic and underarm hair. Is it because many people have a yearning to being pre-pubic again?
The smell /deoderant  thing has got out of hand too.
Where does the social pressure originate from? It just ain't natural. lyner, Thu, 10th Jan 2008

I think it could just be a remnant of evolution.

With evolution and modern living/dressing I don't think it is necessary any more and think that overtime it, hair, will eventually disappear. Sorry to say but I also think that includes head hair.

Any pheromones will still get released regardless of having hair and we now wear clothes that absorb sweat and act as a "wick" instead.

@ sophiecentaur

I think its all media and money related. The deodorant and "smell" industry is worth a fortune and people are made self concious where there is no need to be. Take the introduction of "feminine deodorants", designed to make women self concious of something they had no need to worry about in the past.
BTW
I remember a "top of the pops" where a female artist Nena did a song called "99 red ballons." The song became a hit but it was also famous for the woman appearing on the ToTP stage with hair under her armpits!!!!

There was quite an uproar but it didn't last long, because of media pressure she was made to shave her pits clean. 

Bee


that mad man, Thu, 10th Jan 2008

I can't imagine female fashion going for the bald look for some while - like School uniform, hair is a great cosmetic for distracting attention from other, less attractive features. The only women who look good with no hair are lucky enough to have very good, regular and symmetrical features - the very occasional Pop Singer succeeds with this look.
Some blokes get away with looking a bit 'ard' with very short hair / shaved heads because Women are less superficial in their appreciation of men so it doesn't affect our 'chances'. lyner, Mon, 14th Jan 2008




does this mean that when we shave our armpit and/or pubic hair, our personal scent changes? JnA, Mon, 14th Jan 2008



That's true.

My dad had these work jeans he had at he's old work and a big area on the front of his leg is missing hair and hasn't grown back in the 5 years since he quit. Simulated, Sun, 20th Jan 2008



That's true.

My dad had these work jeans he had at he's old work and a big area on the front of his leg is missing hair and hasn't grown back in the 5 years since he quit.


yes, lots of SCI's get this on parts of their legs that always rubs against the footplate uprights. JnA, Mon, 21st Jan 2008

The purpose of pubic hair, is like a floral show, for primates, in 5 colours.
The shaving apparently is a Hebrew custom, but of course due to fashion or is that peer pressure?
One has to cut down the infectious hair from the nether region, think of the bacteria in that forest, and apparently does cut down yeast type infections etc.
Shaving the hair would limit the distribution of the pheromones.
AlphBravo, Tue, 12th Feb 2008

So to summarize, the purpose of pubic hair is to "hold scent". paros, Sat, 16th Feb 2008

I developed a theory on the purpose of pubic hair 32 years ago when my firstborn was an infant. While laying in bed with him sleeping on my stomach I noticed that when he startled he reached out with his hands, making a grasping motion and his toes came together in a grasping fashion. I was reading a book about a lost tribe in the Phillipines at the time so I was focused on evolution. I believe we have short curly pubic and underarm hair for the babies to hold on to as we walk around. Naturally once we lost body hair we had to keep hair somewhere for the babies to curly their fingers and toes in. This theory is also supported by the fact that we don't get pubic hair until puberty and it becomes sparse and straight after menopause. GingerCooke007, Mon, 11th Aug 2008

how come no other primates sweat or have hair in their nether regions? i cant think of any other animal that sweats jeremy, Wed, 3rd Sep 2008

First of all, you need to understand that human hair loss is due to sexual selection. Males selected hairless females because they were more attractive. Mature females retained hair in the pubic region because it hid the trauma of childbirth and maintained their attractiveness to males (no stitches back then). Males have pubic hair and are relatively hairless as a result of having selected females to be this way and picking up the traits themselves through their mamas. Dave, Sat, 20th Dec 2008

My friend and I have been discussing the purpose of pubic hair. All joking aside, we were wondering if, when we all walked around naked, it was a means for stopping bugs from entering our private areas? further, purhaps when food was 'hunted and gathered' it was also a means for catching brunch? Clare Raine, Thu, 26th Feb 2009

Could it just be garnish? Tony, Sat, 2nd May 2009

...im not 100 percent suer on this but i think garnish means edible. *shivers* MATTZ, Wed, 13th May 2009

I have loads, and think it's there to keep me warm when my clothes fall off on a cold night. kane-o, Sat, 27th Jun 2009

I was just wondering, if pubic hair is a haven for bacteria, could it perhaps be a cause of infection if left to grow realy long or in incontinent older adults? Has anyone ever done any studies on this sort of thing? smokeyjoe, Tue, 17th Nov 2009

We have pubic hair to show that we are sexually mature and fertile. A caveman wants his genes to survive into the future. No sense on picking a female who isn't sexually mature. Steffens Thomas G., Fri, 20th Nov 2009

"Not tonight dear. I'm washing my pubic hair." Shibs, Mon, 30th Nov 2009

I wonder if shaving off the pubic hair deters its purpose though it satisfies the aesthetic sense of today's fashion/fad.  josogomez, Tue, 1st Dec 2009

Well, if you shave it off and decide you don't like being ahem 'bald', you can always wear a merkin. Don_1, Tue, 1st Dec 2009

Well, if you shave it off and then decide you don't like being **cough cough, splutter splutter.... ahem** a baldy, you can always wear a merkin Don_1, Tue, 1st Dec 2009

Well, if you shave it off and then decide you don't like being **cough cough, splutter splutter.... ahem** a baldy, you can always wear a merkin Don_1, Tue, 1st Dec 2009

Well, if you shave it off and then decide you don't like being **cough cough, splutter splutter.... ahem** a baldy, you can always wear one of these http://www.merkinworld.com/history_01.htm Don_1, Tue, 1st Dec 2009

Well, if you shave it off and then decide you don't like being **cough cough, splutter splutter.... ahem** a baldy, you can always wear a merkin. Don_1, Tue, 1st Dec 2009

I thought it protected you from rashes? yor_on, Fri, 4th Dec 2009

Gross, gross, gross! Shave that stuff off!!!!!!! EWWWWW!!! Shaver, Mon, 21st Dec 2009

Wouldn't that be a little rash? yor_on, Fri, 25th Dec 2009

It also seems to be good for reducing friction in sensitive areas, especially when a little perspiration is added. BamaGeek, Tue, 12th Jan 2010

Because our natrual scent is attractive to the other sex and the hair helps release the scent. ch3ls3a, Fri, 15th Jan 2010

So, why do people shave? Is it just so we have a more pleasurable time fucking? Rachel, Sun, 25th Apr 2010

The recent trend of shaving and trimming pubic hair has had some unpleasant consequences for those that do so – unsatisfying sex lives and a corresponding increase in uninformed patients seeking help from sex therapists. The reasons for this lie in human physiology. Persons that shave or trim their pubic hair are unwittingly eliminating from their bodies an extraordinarily powerful ingredient in the recipe for satisfying sexual relations – pheromones, bodily secretions that are unconsciously sensed by the human brain and deemed highly necessary for fulfilling sexual relations by physicians specializing in human sexuality. A specialized structure located inside the nose called the Vomeronasal organ detects invisible airborne and odorless pheromone molecules that are produced in specialized sweat glands (apocrine glands) which occur primarily in the genital and axillary areas, and to a lesser degree in the naval and anal areas of the body. Body hair in these areas trap and concentrate the apocrine gland pheromone secretions, where naturally occurring bacteria begin to decompose them. During this natural decomposition process, pheromones are released into the air as sweat evaporates from the skin and body hair. Once airborne, especially during sexual relations, these pheromones are sensed by the Vomeronasal organ. These signals are then sent through specialized nerves to a part of the brain called the hypothalamus -- a part known for its capacity to alter one's emotions, hormones, and sexual behavior. During sexual relations, the effect of pheromones is extraordinarily powerful, resulting in a high degree of stimulation and activity. Elimination or reduction of body hair in the area of the apocrine glands results in a corresponding reduction of pheromones. This in turn translates into mildly to highly decreased sexual stimulation of one’s sexual partner. The main pheromones produced by the apocrine glands are: In males: Androstenone, Androstenol, and Androsterone. These pheromones strongly increase the desire for sexual intercourse in women. In females: Copulins, an assortment of fatty acids and other biological molecules that serve to induce copulation in men. Interestingly, research has demonstrated that homosexual males and females react as strongly to pheromones released by members of their own sex, as heterosexual males and females respond to pheromones released by member of the opposite sex. Juan, Sat, 18th Sep 2010

I think that you all have sex on the brain. The most logical reason we have pubic hair is to reduce friction in areas that rub together and to dissipate sweat. I agree with the other reasons for pubic hair being for pheromone secretion and mate attraction but it's not the only case. Have a go at shaving a region in a confined space on the body and take note of how much more sweat seems to accumulate. Also if you rub you finger across a portion of your underarm with no hair and then across a portion with hair you will notice a significant difference in the amount of friction created between your finger and underarm skin. Just a thought, could do with some real scientific investigation though. Pabs, Thu, 15th Mar 2012

Has one ever thought of why a man perfers a woman to be shaved or bald down there in their nether regions. Has one ever thought that maybe the man has some subconscience or secret desire to have his partner look more like a pre-puberty young girl who has yet to grow pubic hair? Kelly, Sat, 14th Jul 2012

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