What purpose do labia minora serve?

[diggleblop]

I've noticed in my voyeurism of the female form, that all vaginas look different. But I've really noticed in person and in pics that some women have huge inner labia and some have almost none at all.

What is the deal with this? What purpose does it serve and why do some women have large labia and some have really small?

[Drum God]

In a bit of a mood, are we? (http://boards.straightdope.com/sdmb/showthread.php?t=381463)

[diggleblop]

Just fighting my ignorance. Any ideas on the questions? :)

[spingears]

Just fighting my ignorance. Any ideas on the questions? :)
Windshield wipers?

[Fear Itself]

They are to keep bees out.

[bouv]

They are to keep bees out.

But as an unintended side effect, it also keeps the centipedes in.

[Anaamika]

But as an unintended side effect, it also keeps the centipedes in.
Holy crap. The mere thought. *faints*

[malkavia]

It's to give the pussy troll a bit of privacy.



What?

[CandidGamera]

Vaginal puppetry.

[ShibbOleth]

Without the lips it is more difficult to perform a monologue.

[hawthorne]

Umami punani.

[rhiannon777]

What purpose does it serve and why do some women have large labia and some have really small?

Male and female sex organs are formed from the same embryonic tissue. For the first few weeks, a fetus has a genetic sex but it's not physically differentiated. So the same tissue that forms the head of the penis in males forms the clitoris in females. The same tissue that forms the scrotum forms the labia majora. And the same tissue that forms the phallus forms the labia minora. So it's possible that the labia minora are partially a vestigal organ--women have them because men need that tissue to do something evolutionarily valuble.

On a more practical note, the labia minora serve the purpose of additional protection for the vagina and urethra. Also, many (or most, according to Masters & Johnson) women who orgasm through sexual intercourse alone (as opposed to clitoral stimulation) are orgasming because the folds of the labia minora meet over the head of the clitoris...during penetration, the labia minora are rubbed back and forth and can stimulate the clitoris, resulting in orgasm.

As for why some many have small labia and some women have large...well, on one hand, it just chalks up to individual differences. Much like some people have blue eyes, some people have brown eyes. Some men have large testicles, some have small. There's probably an element of sexual selection at work, too...perhaps some primitive men were attracted to petite labia, some to large.

[bouv]

Holy crap. The mere thought. *faints*

Oh, so you're going to come in here and tell me that women don't have centipedes in their vaginas?

[diggleblop]

Thanks, rhiannon777

[Nic2004]

Male and female sex organs are formed from the same embryonic tissue. For the first few weeks, a fetus has a genetic sex but it's not physically differentiated. So the same tissue that forms the head of the penis in males forms the clitoris in females. The same tissue that forms the scrotum forms the labia majora. And the same tissue that forms the phallus forms the labia minora. So it's possible that the labia minora are partially a vestigal organ--women have them because men need that tissue to do something evolutionarily valuble.

On a more practical note, the labia minora serve the purpose of additional protection for the vagina and urethra. Also, many (or most, according to Masters & Johnson) women who orgasm through sexual intercourse alone (as opposed to clitoral stimulation) are orgasming because the folds of the labia minora meet over the head of the clitoris...during penetration, the labia minora are rubbed back and forth and can stimulate the clitoris, resulting in orgasm.

As for why some many have small labia and some women have large...well, on one hand, it just chalks up to individual differences. Much like some people have blue eyes, some people have brown eyes. Some men have large testicles, some have small. There's probably an element of sexual selection at work, too...perhaps some primitive men were attracted to petite labia, some to large.
Great reply and great subject for a debut! Welcome to the Board. You'll do well here.

[Rigamarole]

And the same tissue that forms the phallus forms the labia minora. So it's possible that the labia minora are partially a vestigal organ--women have them because men need that tissue to do something evolutionarily valuble.

Ah, so now women can look at their labia minora and say, "if I had a dick, it would be huge/small!"

[CC]

I say someone should pony up rhiannon's entry fee, and we open the gates. Anyone who can stand up against the silly and ick of the first few posts and still post such an informative and worthwhile response deserves a spot amongst the teeming millions. And failing that, she ought to pay her own way and join us anyway. Welcome, toots.

[Rysdad]

So it's possible that the labia minora are partially a vestigal organ--women have them because men need that tissue to do something evolutionarily valuble.

What does drawing a little image of Fidel Castro with funny lips using a Magic Marker on a woman's groin have to do with evolution?

[Sunrazor]

I say someone should pony up rhiannon's entry fee, and we open the gates. Anyone who can stand up against the silly and ick of the first few posts and still post such an informative and worthwhile response deserves a spot amongst the teeming millions. And failing that, she ought to pay her own way and join us anyway. Welcome, toots.
Oh, yeah, well, anybody can Google "labia" and manage to come up with some scientific explanation -- that's the easy part. But can she keep up with the scintillating and whimsical humor of these threads? Hmmmm? Besides, nobody offered to pony up my subscription fee when I was holding forth, after great research and and fact-checking, on whether "kitchen," when used in the phrase "kitchen floor," is an adjective. Hah! Pay yer own way, kid!

Oh, yeah, and when somebody offers pie? It ain't real pie!

Errrr ... maybe this wasn't the best thread to offer that insight ...

[Telperien]

Oh, so you're going to come in here and tell me that women don't have centipedes in their vaginas?

Haven't had a girlfriend in a while, have you?

[Beware of Doug]

This is as good a time as any to mention Venice's Palazzo Labia (http://en.wikipedia.org/wiki/Palazzo_Labia).

[Malacandra]

Haven't had a girlfriend in a while, have you?

That's just asking for a tu quoque. :p

[Rumpleforskin]

is there even a cunt hair's difference between the two? :(

[ShibbOleth]

I say someone should pony up rhiannon's entry fee, and we open the gates. Anyone who can stand up against the silly and ick of the first few posts and still post such an informative and worthwhile response deserves a spot amongst the teeming millions. And failing that, she ought to pay her own way and join us anyway. Welcome, toots.

I was going to, but then I realized that she misspelled "valuable", so instead I shall have to pit her. Pity, that.

;)

[Joey P]

Oh, yeah, and when somebody offers pie? It ain't real pie!

No, no, no, you have that all wrong. We don't offer pie, we tell you to bring pie...when come back. :D

[cmkeller]

Rysdad:

What does drawing a little image of Fidel Castro with funny lips using a Magic Marker on a woman's groin have to do with evolution?

Commie bastard!

A REAL American would have said Willie Nelson!

[ultrafilter]

Also, many (or most, according to Masters & Johnson) women who orgasm through sexual intercourse alone (as opposed to clitoral stimulation) are orgasming because the folds of the labia minora meet over the head of the clitoris...during penetration, the labia minora are rubbed back and forth and can stimulate the clitoris, resulting in orgasm.

There is a theory that the female orgasm is evolutionarily valuable because it keeps a woman from getting up and walking away right after sex. In other apes that's not a big deal, but because we stand upright, the vagina is pointed straight down and the semen can leak out. So this function might be important.

[TokyoBayer]

They don't get up and walk away? :dubious: Have I been hanging around with the wrong crowd again? :smack:

[Chronos]

There is a theory that the female orgasm is evolutionarily valuable because it keeps a woman from getting up and walking away right after sex.There's also a theory that it's valuable because women who like having sex will do so more often. I know which theory I consider simpler.

[Telperien]

That's just asking for a tu quoque. :p

Well, I admit I've not had a girlfriend in a while, either. Or a boyfriend.

grumble

[ultrafilter]

There's also a theory that it's valuable because women who like having sex will do so more often. I know which theory I consider simpler.

They're not really competing theories, though. And a single adaptation that makes an organism mate more often and be more likely to be made pregnant as a result of that mating is a big win from an evolutionary standpoint.

[Excalibre]

But as an unintended side effect, it also keeps the centipedes in.
:: becomes gayer ::

[Sunrazor]

No, no, no, you have that all wrong. We don't offer pie, we tell you to bring pie...when come back. :D
Yeah, well, either way, I haven't gotten any damn pie, but it's sure been talked about a lot. I'm just sayin' -- I've had a lot of stuff e-mailed to me by fellow Dopers, but nothin' I could enjoy with a cup of coffee.

[Rysdad]

A REAL American would have said Willie Nelson!

Depends a lot on the 'foliage'.

Carrot Top?

Tommy Chong?

Jerry Garcia?

This guy? (http://service.spiegel.de/cache/international/spiegel/0%2C1518%2Cgrossbild-421872-335660%2C00.html)

[WhyNot]

There is a theory that the female orgasm is evolutionarily valuable because it keeps a woman from getting up and walking away right after sex. In other apes that's not a big deal, but because we stand upright, the vagina is pointed straight down and the semen can leak out. So this function might be important.
Except it doesn't. Go straight down, I mean. It's tilted anteriorally (illy?) at the cervix, creating a little swimming pool when you stand up. You can see it in this very simply drawn schematic, which I think is safe for work: here. (http://www.menstruation.com.au/pubertyplace/images/insert.jpg) Plus, when fertile, a woman's cervix is a few millimeters lower than in that picture, dipping down into the "pool". When a woman orgasms, her cervix actually sucks semen up into the uterus if it's a fertile day. When a woman's not fertile, the cervix is high and firm, like that picture, and it doesn't matter if the woman stands on her head - no amount of semen in the uterus will get her pregnant.

So the female orgasm may be reproductively useful for the sucking of semen. But even if she stands up, most of the semen will stay inside her. (Some does drip out, but most stays in.)

[Spiff]

I think some field testing is in order.

:: Rings up Mrs. Spiff ::

"But Honey, who are you to stand in the way of scientific advancement?"

[DSYoungEsq]

There's also a theory that it's valuable because women who like having sex will do so more often. I know which theory I consider simpler.
Oh SURRRRRRRE. Bring that damned Rasor into play... :D

[priapus]

Slight hijack..I just wanna know why women always go into the bathroom before having sex? It doesn't always taste like they are cleaning up the equipment especially

[drachillix]

They don't get up and walk away? :dubious: Have I been hanging around with the wrong crowd again? :smack:

Or they have. :dubious:

:D

[Count Blucher]

[QUOTE=rhiannon777] women have them because men need that tissue to do something evolutionarily valuble. QUOTE]

I just Knew they were there as 'tongue-ticklers' to increase our pleasure. :p

[twickster]

Slight hijack..I just wanna know why women always go into the bathroom before having sex? It doesn't always taste like they are cleaning up the equipment especially

If your bladder is full, you're more likely to get a urine leakage, which increases the possibility of a UTI.

[tashabot]

Slight hijack..I just wanna know why women always go into the bathroom before having sex? It doesn't always taste like they are cleaning up the equipment especially

Well, the reason *I* go to the bathroom after sex is because I have to pee.

You've gotta understand something about female anatomy: when you're having sex there's the disting possiblity and probability that the urethra is getting rubbed up against. If I have any liquid whatsoever in my bladder and that happens, I generally have to pee.

While I'm in there I also clean up - I personally think semen smells weird when mixed with vaginal fluid and no amount of smoking has made me unable to smell that when I'm trying to go to sleep afterward.

~Tasha

[Monstre]

That's just asking for a tu quoque.
Well, I admit I've not had a girlfriend in a while, either. Or a boyfriend.

In that case, she's probably just asking for one quoque. No need to set the bar too high. ;)


Well, the reason *I* go to the bathroom after sex is because I have to pee.
Actually, priapus asked about before, not after. But I think twickster addressed it.

or perhaps it's just centipede removal

[Dag Otto]

I personally think semen smells weird when mixed with vaginal fluid and no amount of smoking has made me unable to smell that when I'm trying to go to sleep afterward.


Wow. So that's the reason for the cigarette afterwards?

[danceswithcats]

While I'm in there I also clean up - I personally think semen smells weird when mixed with vaginal fluid and no amount of smoking has made me unable to smell that when I'm trying to go to sleep afterward.

~Tasha
If you're smoking, then reduce speed of copulation and/or use lubrication. No one likes the odor of burnt genetalia.

[Der Trihs]

Plus, when fertile, a woman's cervix is a few millimeters lower than in that picture, dipping down into the "pool". When a woman orgasms, her cervix actually sucks semen up into the uterus if it's a fertile day.Which leads to another theory that I've heard; that the female orgasm makes cheating more efficient. The claim is that women are more likely to orgasm with a lover than a husband, and therefore are more likely to get pregnant by him.

[The Weird One]

Slight hijack..I just wanna know why women always go into the bathroom before having sex? It doesn't always taste like they are cleaning up the equipment especially
Hmm, I don't always go to the bathroom before sex, if caught up in the moment, but I try to. If my bladder is feeling even the slightest bit full, then I want to empty it so I don't feel like I have to pee at an inopportune moment. I also clean up while I'm in there. Frankly, I wish more men would do the same. I've definitely dated guys who smelled pretty funky down there.

I can't speak to why someone would go to the bathroom right before sex and not clean up.

[danceswithcats]

If your bladder is full, you're more likely to get a urine leakage, which increases the possibility of a UTI.Help me out here-urine leakage increases chance of a UTI how? Logically-I'd think that flushing the mains would preclude entrance of the nasties causing a UTI. :confused:

[Guinastasia]

Oh, so you're going to come in here and tell me that women don't have centipedes in their vaginas?


Well, the teeth down there usually take care of them...

;)

[Sam Stone]

Do they really need a purpose, people?

Science is all well and good, but some things just don't have to justify their existence. Next you'll be asking why puppies are so damned cute.

[FormerMarineGuy]

Do they really need a purpose, people?

Science is all well and good, but some things just don't have to justify their existence. Next you'll be asking why puppies are so damned cute.

Shit! This was going to be by next question on GQ. I at least deserve an answer to it, now.

[twickster]

Help me out here-urine leakage increases chance of a UTI how? Logically-I'd think that flushing the mains would preclude entrance of the nasties causing a UTI. :confused:

Dunno -- paging QtM -- just know it's standard medical advice for preventing UTI's. Every non-virgin adult woman has had a UTI at some point, often after a period of unusually active sexual activity (aka "honeymoon cystitis"); when you go to the doctor, you get the scrip for antibiotics and a reminder that emptying your bladder before sex is a good idea, because it will decrease the likelihood of future occurences.

Depending on the intelligence of the woman, she may need to hear this more than once before she starts heeding it -- but I'm guessing most women over 25 usually do, unless the moment is particularly, ah, urgent.

[Annie]

Dunno -- paging QtM --

Does he get a lot of cooter maintenance experience working at the prison? Although I'm sure his treatment history of crotch misadventures has some relevance....

[Der Trihs]

Next you'll be asking why puppies are so damned cute.Because they have mammalian-babyish characteristics, and we instinctively find those cute, in order to encourage us to care for our own children.

[Jake]

Which begs the question (to me), why didn't og place the clitoris closer to the vagana?
Seems like it would be more fun for women. (more orgasms)
But then it seems to do very well where it is!

[The Weird One]

<snip>a reminder that emptying your bladder before sex is a good idea, because it will decrease the likelihood of future occurences.
I've thought you were supposed to go to the bathroom after sex to prevent UTIs. The way I heard it, sex increases the chance of a UTI because, in all the rubbing around, bacteria from the vagina can get moved to the urinary tract, where they climb up, multiply, and cause great unpleasantness. Peeing after sex flushes out any little buggers that might've migrated.

[twickster]

Does he get a lot of cooter maintenance experience working at the prison?

He's got plenty of experience outside the slammer -- I believe he did family practice for many years.

[saoirse]

There's also a theory that it's valuable because women who like having sex will do so more often. I know which theory I consider simpler.

I thought it was pretty well established that women had orgasms because men had orgasms. The ability to do so is physiological, and established prior to sex differentiation in the womb. Whatever evolutionary advantages it adds are fortunate but incidental.

[StarvingButStrong]

I think the peeing before is mainly a comfort thing. During sex a certain number of cubic inches of flesh is going to be added to the contents of your pelvic area, pushing other organs aside to make room. Having your bladder empty serves to keep it from being squashed about and possibly having some urine forced out.

As for relating to UTI, what I was told is that having the bladder empty/flaccid reduced how likely it was to be bruised during, well, during. Bruising makes it easier for bacteria to get a foothold, so to speak, whether the bacteria get there as a result of sex or were already floating around in the area.

[sinjin]

I thought it was pretty well established that women had orgasms because men had orgasms.

Yeah, because chicks are totally turned on by the male orgasm. It pretty much just pushes them over the edge. That's why porn always ends with the money shot. It gives the ladies something to write home about. ;)

[chorpler]

I thought it was pretty well established that women had orgasms because men had orgasms. The ability to do so is physiological, and established prior to sex differentiation in the womb. Whatever evolutionary advantages it adds are fortunate but incidental.

Does that mean that all female animals have the ability to orgasm, then, and they just hardly ever get the opportunity?

[irishgirl]

Emptying the bladder before intercourse- means that any bacteria that get there aren't left sitting in a nice, warm culture medium (urine).

Emptying the bladder after intercourse flushes any bacteria that have made it into the urethra or bladder, out.
Or at least, that is the theory.

Some cases of "honeymoon cystitis" may not be UTIs at all. Certainly several women report symptoms far too close in time to the act of intercourse to make an actual bacterial infection likely.

If you're getting urgency, burning, frequency etc. immediately after intercourse, it's more likely to be physical irritation of the urethra, from friction, rather than a lower urinary tract infection.

[twickster]

Thanks, irishgirl! (And my apologies for forgetting that this was your field.)

[saoirse]

Does that mean that all female animals have the ability to orgasm, then, and they just hardly ever get the opportunity?

I am not a bioligist, so I can refer you to reviews (http://www.nytimes.com/2005/05/17/science/17orga.html?ei=5070&en=db3cf43558b4b57c&ex=1156219200&adxnnl=1&adxnnlx=1156097230-gDpH0f/0QwJceGdJgeNdnA) of a book (http://www.slate.com/id/2119551/) on the subject.

As one of the writers points out, this is nothing new, and largely accepted in scientific community, but speculation on possible evolutionary advantages is so much more fun, and allows people to confirm their own biases about male and female sexuality, that it is routinely ignored.

Simply put, the theory says:

[F]emale orgasms are simply artifacts - a byproduct of the parallel development of male and female embryos in the first eight or nine weeks of life.
In that early period, the nerve and tissue pathways are laid down for various reflexes, including the orgasm, Dr. Lloyd said. As development progresses, male hormones saturate the embryo, and sexuality is defined.
In boys, the penis develops, along with the potential to have orgasms and ejaculate, while "females get the nerve pathways for orgasm by initially having the same body plan."
Nipples in men are similarly vestigial, Dr. Lloyd pointed out.