# Why do we have the same organs for sex and excrement? **URL:** \ **Category:** Factual Questions\ **Created:** [January 24, 2003, 12:12am UTC](https://boards.straightdope.com/t/why-do-we-have-the-same-organs-for-sex-and-excrement/150571 "2003-01-24T00:12:34Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![kniz](https://avatars.discourse-cdn.com/v4/letter/k/c37758/32.png) [@kniz](https://boards.straightdope.com/u/kniz)\ **Post date:** [January 24, 2003, 7:48pm UTC](https://boards.straightdope.com/t/why-do-we-have-the-same-organs-for-sex-and-excrement/150571/21 "2003-01-24T19:48:17Z")
> [@](#): > > \*Originally posted by Lemur866 \* > \*\*Early reptiles evolved a system of internal fertiliztion where they put their cloacas together, the male releases sperm which swims up the female’s cloaca. Some reptiles have versions of penises, which are pretty much simply extensions of the cloaca that make the cloacal “docking” easier. Our mammal-like reptile ancestors had this system, and we’ve elaborated on it ever since with our mammal penises. \*\* To carry this comparison one step farther: > [@](#): > > It is for this reason that male and female reproductive and sexual organs are more [**alike**](http://www.the-clitoris.com/n_html/n_develop.htm) than they first appear. The clitoris is actually a penis that is not fully developed, or another way of looking at it, a penis is a fully developed clitoris. This is true of the other parts of the male and female reproductive organs. ---
**Author:** ![toadspittle](https://avatars.discourse-cdn.com/v4/letter/t/c0e974/32.png) [@toadspittle](https://boards.straightdope.com/u/toadspittle)\ **Post date:** [January 24, 2003, 7:57pm UTC](https://boards.straightdope.com/t/why-do-we-have-the-same-organs-for-sex-and-excrement/150571/22 "2003-01-24T19:57:55Z")
> [@](#): > > That’s why you wake up with morning boner, so you don’t pee the bed. I think this is the only questionable part of your post. An amusing theory, though. ---
**Author:** ![Splanky](https://avatars.discourse-cdn.com/v4/letter/s/b2d939/32.png) [@Splanky](https://boards.straightdope.com/u/Splanky)\ **Post date:** [January 24, 2003, 8:05pm UTC](https://boards.straightdope.com/t/why-do-we-have-the-same-organs-for-sex-and-excrement/150571/23 "2003-01-24T20:05:03Z")
> [@](#): > > Ever notice you can’t pee when you have an erection I’m pretty sure you can. You can’t ejaculate and pee at the same time, but I’m pretty sure I’ve peed with a boner before. ---
**Author:** ![Ephemera](https://avatars.discourse-cdn.com/v4/letter/e/8baadc/32.png) [@Ephemera](https://boards.straightdope.com/u/Ephemera)\ **Post date:** [January 24, 2003, 8:14pm UTC](https://boards.straightdope.com/t/why-do-we-have-the-same-organs-for-sex-and-excrement/150571/24 "2003-01-24T20:14:18Z")
> [@](#): > > > [@](#): > > > > Ever notice you can’t pee when you have an erection > > I’m pretty sure you can. You can’t ejaculate and pee at the same time, but I’m pretty sure I’ve peed with a boner before. Well, I **know** I have. Woohoo, I’m special! ---
**Author:** ![smiling\_bandit](https://avatars.discourse-cdn.com/v4/letter/s/e9a140/32.png) [@smiling\_bandit](https://boards.straightdope.com/u/smiling_bandit)\ **Post date:** [January 24, 2003, 8:17pm UTC](https://boards.straightdope.com/t/why-do-we-have-the-same-organs-for-sex-and-excrement/150571/25 "2003-01-24T20:17:35Z")
Its possible, but difficult. And you have to get part-way relaxed first. Rather annoying sometimes. ---
**Author:** ![levdrakon](https://avatars.discourse-cdn.com/v4/letter/l/49beb7/32.png) [@levdrakon](https://boards.straightdope.com/u/levdrakon)\ **Post date:** [January 24, 2003, 8:17pm UTC](https://boards.straightdope.com/t/why-do-we-have-the-same-organs-for-sex-and-excrement/150571/26 "2003-01-24T20:17:52Z")
Yup, you can pee with a boner, and pardon the pun but it is _hard_. I think the reason for early morning woodies is your bladder is full and pressing against your prostate. Voila, boner. ---
**Author:** ![Eve](https://avatars.discourse-cdn.com/v4/letter/e/9e8a1a/32.png) [@Eve](https://boards.straightdope.com/u/Eve)\ **Post date:** [January 24, 2003, 8:21pm UTC](https://boards.straightdope.com/t/why-do-we-have-the-same-organs-for-sex-and-excrement/150571/27 "2003-01-24T20:21:34Z")
. . . So we don’t know whether we’re coming or going? ---
**Author:** ![Snickers](https://avatars.discourse-cdn.com/v4/letter/s/5daacb/32.png) [@Snickers](https://boards.straightdope.com/u/Snickers)\ **Post date:** [January 24, 2003, 9:44pm UTC](https://boards.straightdope.com/t/why-do-we-have-the-same-organs-for-sex-and-excrement/150571/28 "2003-01-24T21:44:37Z")
> [@](#): > > \*Originally posted by PumiceT \* > \*\*So, we’re talking about the penis. Ever notice you can’t pee when you have an erection? \*\* Wow…you mean someone’s actually _tried_ to do this? Fascinating. Snicks ---
**Author:** ![Snickers](https://avatars.discourse-cdn.com/v4/letter/s/5daacb/32.png) [@Snickers](https://boards.straightdope.com/u/Snickers)\ **Post date:** [January 24, 2003, 9:47pm UTC](https://boards.straightdope.com/t/why-do-we-have-the-same-organs-for-sex-and-excrement/150571/29 "2003-01-24T21:47:19Z")
…and I see after posting, not just one, but several people have. Apparently this is quite common. Still fascinating. Waiting for the guy to check in who’s tried it while ejaculating - our enquiring minds need to know! Alas, I cannot try it myself; I lack the proper equipment. Snicks ---
**Author:** ![Jus\_Checkin](https://avatars.discourse-cdn.com/v4/letter/j/e480ec/32.png) [@Jus\_Checkin](https://boards.straightdope.com/u/Jus_Checkin)\ **Post date:** [January 24, 2003, 9:51pm UTC](https://boards.straightdope.com/t/why-do-we-have-the-same-organs-for-sex-and-excrement/150571/30 "2003-01-24T21:51:36Z")
> [@](#): > > \*Originally posted by Lissa \* > \*\*I see where \*\* caracal’s \*\* question comes from, though. I’ve often wondered the same thing, but my curiosity involved bacteria. > > It seems that bacteria in the urine traces (or in the case of birds, fecal traces) left in the urethra of the male might in some way damage the sperm, or in some way affect the female’s uterus or ovaries. In an evolutionary sense, any hinderance to sperm usually is weeded out through natural selection, so is the bacteria not harmful at all? \*\* Urine does not contain bacteria unless you have a bladder infection. Women do tend to get bladder infections more often if they are sexually active because of the close proximity of the anus to the vagina and urethra. Mix it up a bit and BAM you’ve got a bladder infection. ---
**Author:** ![Jus\_Checkin](https://avatars.discourse-cdn.com/v4/letter/j/e480ec/32.png) [@Jus\_Checkin](https://boards.straightdope.com/u/Jus_Checkin)\ **Post date:** [January 24, 2003, 9:59pm UTC](https://boards.straightdope.com/t/why-do-we-have-the-same-organs-for-sex-and-excrement/150571/31 "2003-01-24T21:59:05Z")
> [@](#): > > \*Originally posted by Lemur866 \* > \*\*Think about how mammalian reproduction evolved. You have to go back to when we were fish. … \*\* I don’t know about you but I was never a FISH! ---
**Author:** ![caracal](https://avatars.discourse-cdn.com/v4/letter/c/91b2a8/32.png) [@caracal](https://boards.straightdope.com/u/caracal)\ **Post date:** [January 24, 2003, 10:37pm UTC](https://boards.straightdope.com/t/why-do-we-have-the-same-organs-for-sex-and-excrement/150571/32 "2003-01-24T22:37:13Z")
> [@](#): > > \*Originally posted by Lemur866 \* > \*\*Think about how mammalian reproduction evolved. You have to go back to when we were fish. Typical reproductive strategy then is for the female to dump a bunch of eggs on the sea floor, and the male swims up and sprays sperm all over them. Not a very complicated system, which uses a common duct to excrete solid wastes, urea, and gametes. > > Mammals and other land vertebrates are simply inheritors of this system, albeit modified. Early reptiles evolved a system of internal fertiliztion where they put their cloacas together, the male releases sperm which swims up the female’s cloaca. Some reptiles have versions of penises, which are pretty much simply extensions of the cloaca that make the cloacal “docking” easier. Our mammal-like reptile ancestors had this system, and we’ve elaborated on it ever since with our mammal penises. \*\* If if had phrased my question better (I should have used the term Natural Selection somewhere), this is along the lines of the answer I was looking for.🙂 As for peeing with an erection, I don’t have a problem with it at all. However, I haven’t experienced this in a few of years. Now that I think about it, I believe that ,um, “boner urine”:D, was always a result of too much alcohol in my system. This usually occured after a night of bar-hopping. Has anyone else experienced this? Every instance I can think of took place at some strange woman’s house. I think the female equivalent would be the extreme weight gain that these women would go through over the course of the night. I stopped drink a few years ago, and since have never experienced either of the phenomena since.😃 ---
**Author:** ![alice\_in\_wonderland](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/alice_in_wonderland/32/176_2.png) [@alice\_in\_wonderland](https://boards.straightdope.com/u/alice_in_wonderland)\ **Post date:** [January 24, 2003, 10:58pm UTC](https://boards.straightdope.com/t/why-do-we-have-the-same-organs-for-sex-and-excrement/150571/33 "2003-01-24T22:58:01Z")
> [@](#): > > \*Originally posted by PumiceT \* > \*\*That’s why you wake up with morning boner, so you don’t pee the bed. \*\* But women don’t get boners, and most of us don’t pee the bed. I know personally, when I have to go I just wake up. I’m thinkin’ there may be some flawed logic here. 😉 ---
**Author:** ![sunstone](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sunstone/32/3372_2.png) [@sunstone](https://boards.straightdope.com/u/sunstone)\ **Post date:** [January 24, 2003, 11:42pm UTC](https://boards.straightdope.com/t/why-do-we-have-the-same-organs-for-sex-and-excrement/150571/34 "2003-01-24T23:42:49Z")
As I recall (sorry that I don’t have my mammalian embryology texts available, and it has been many years since I took the courses at university), the root cause of the relative coexistence of the excretory and reproductive systems is as follows: The gonads (ovaries and testes are both termed gonads by biology types) actually develop from kidney-like structures which have the same sort of macro anatomy as the testes…and have the same sort of tubing attached. However, in mammals, these become gonads, and there is a second and very similar set of organs that go on to develop into kidneys and the tubes that are associated with them. Therefore, the two systems are located in the same area, have similar gross anatomy, and at least in the male, share part of the tubing. Wow…it has been a long time. I hope I have the general concept correect. ---
**Author:** ![Cisco](https://avatars.discourse-cdn.com/v4/letter/c/ccd318/32.png) [@Cisco](https://boards.straightdope.com/u/Cisco)\ **Post date:** [January 24, 2003, 11:59pm UTC](https://boards.straightdope.com/t/why-do-we-have-the-same-organs-for-sex-and-excrement/150571/35 "2003-01-24T23:59:43Z")
> [@](#): > > \*Originally posted by Snickers \* > \*\*Wow…you mean someone’s actually _tried_ to do this? Fascinating. > > Snicks \*\* Every morning from age 8 or 9 until at least 19 or 20. A lot of mornings to this day. Are you male and you’ve never had to do this? ---
**Author:** ![Mephisto](https://avatars.discourse-cdn.com/v4/letter/m/48db29/32.png) [@Mephisto](https://boards.straightdope.com/u/Mephisto)\ **Post date:** [January 25, 2003, 12:04am UTC](https://boards.straightdope.com/t/why-do-we-have-the-same-organs-for-sex-and-excrement/150571/36 "2003-01-25T00:04:19Z")
I can pee out of an erection, too. Talk about your golden arches. But anyway . . . I’ve heard that the nightly erections experienced by most men are due to the body periodically sending more blood to the genital region to ensure that all the penile tissue is properly oxygenated. Guys who wake up during this periodic tumescense experience “morning wood.” I have no idea if nightly erections are really necessary for penile health and would appreciate any information or informed speculation that can be offered by any Doper who may read this. Hopefully this isn’t too much of a hijack since the phenomena has already been mentioned in this thread. On a less serious note . . . > [@](#): > > \*Originally posted by caracal \* > \*\*But why do we (and other animals) use the same organs for sex and waste? How are they related? \*\* I’ve never excreted waste from my hand . . . ---
**Author:** ![X\_Slayer\_ALE](https://avatars.discourse-cdn.com/v4/letter/x/bbe5ce/32.png) [@X\_Slayer\_ALE](https://boards.straightdope.com/u/X_Slayer_ALE)\ **Post date:** [January 25, 2003, 12:13am UTC](https://boards.straightdope.com/t/why-do-we-have-the-same-organs-for-sex-and-excrement/150571/37 "2003-01-25T00:13:04Z")
> [@](#): > > \*Originally posted by levdrakon \* > \*\*Yup, you can pee with a boner, and pardon the pun but it is _hard_. > > I think the reason for early morning woodies is your bladder is full and pressing against your prostate. Voila, boner. \*\* IANAD but I’ve seen a lot of programs on Erectile Dysfunction (no reason other than I cant reach the remote to change channel) The erectile function is normally in the ON position. When you are completely relaxed (as in asleep)the muscle that normally prevents the blood from engorging the penis also relaxes and _viola!_ hello woody! one of the ways prior to viagra was to inject a muscle relaxant directly into the penis! Thats when I quickly got up and manually changed channels… :eek: ---
**Author:** ![Jpeg\_Jones](https://avatars.discourse-cdn.com/v4/letter/j/4bbf92/32.png) [@Jpeg\_Jones](https://boards.straightdope.com/u/Jpeg_Jones)\ **Post date:** [January 25, 2003, 12:31am UTC](https://boards.straightdope.com/t/why-do-we-have-the-same-organs-for-sex-and-excrement/150571/38 "2003-01-25T00:31:30Z")
I’d like to be the first to coin a new word: [clears throat] **SEXCREMENT!** ---
**Author:** ![Jpeg\_Jones](https://avatars.discourse-cdn.com/v4/letter/j/4bbf92/32.png) [@Jpeg\_Jones](https://boards.straightdope.com/u/Jpeg_Jones)\ **Post date:** [January 25, 2003, 12:33am UTC](https://boards.straightdope.com/t/why-do-we-have-the-same-organs-for-sex-and-excrement/150571/39 "2003-01-25T00:33:19Z")
> [@](#): > > \*Originally posted by X~Slayer(ALE) \* > **[snip] …and _viola!_ hello woody![/snip]** As a violist, I am offended. Or possibly flattered. ---
**Author:** ![rowrrbazzle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rowrrbazzle/32/414_2.png) [@rowrrbazzle](https://boards.straightdope.com/u/rowrrbazzle)\ **Post date:** [January 25, 2003, 2:04am UTC](https://boards.straightdope.com/t/why-do-we-have-the-same-organs-for-sex-and-excrement/150571/40 "2003-01-25T02:04:33Z")
> [@](#): > > All men who are physically able to get an erection will experience normal erections while asleep. They occur during periods of dream sleep and the reasons for them are unknown. A healthy man can experience from one to five normal erections a night, each lasting fifteen to forty minutes or longer. The morning erection that men often wake up with is simply the last sleep erection of the night and has nothing to do with the need to urinate, as is commonly thought. [http://www.urologyhealthcenter.com/documents/impotence.html](http://www.urologyhealthcenter.com/documents/impotence.html) [Previous page](https://boards.straightdope.com/t/why-do-we-have-the-same-organs-for-sex-and-excrement/150571.md?page=1) [Next page](https://boards.straightdope.com/t/why-do-we-have-the-same-organs-for-sex-and-excrement/150571.md?page=3)