# The non-evolution of the human anus??? **URL:** \ **Category:** Factual Questions\ **Created:** [July 15, 2008, 9:48pm UTC](https://boards.straightdope.com/t/the-non-evolution-of-the-human-anus/456605 "2008-07-15T21:48:28Z")\ **Posts on this page:** 20\ **Page:** 3
**Author:** ![Malacandra](https://avatars.discourse-cdn.com/v4/letter/m/45deac/32.png) [@Malacandra](https://boards.straightdope.com/u/Malacandra)\ **Post date:** [July 16, 2008, 1:47pm UTC](https://boards.straightdope.com/t/the-non-evolution-of-the-human-anus/456605/41 "2008-07-16T13:47:45Z")
[QUOTE=mr. jp] Man is the only animal that flushes - or needs to. [/QUOTE] Well played, sir! 😃 ---
**Author:** ![lobotomyboy63](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lobotomyboy63/32/2900_2.png) [@lobotomyboy63](https://boards.straightdope.com/u/lobotomyboy63)\ **Post date:** [July 16, 2008, 1:50pm UTC](https://boards.straightdope.com/t/the-non-evolution-of-the-human-anus/456605/42 "2008-07-16T13:50:18Z")
[QUOTE=chowder] Threads like this are the reason I love the SDMB. Now I feel the pressing need for a good satisfying dump, will someone pass me a rabbit or summink [/QUOTE] It’s a bit contagious, like yawning, I think…BRB! :smack: 😃 ---
**Author:** ![lieu](https://avatars.discourse-cdn.com/v4/letter/l/c2a13f/32.png) [@lieu](https://boards.straightdope.com/u/lieu)\ **Post date:** [July 16, 2008, 2:23pm UTC](https://boards.straightdope.com/t/the-non-evolution-of-the-human-anus/456605/43 "2008-07-16T14:23:04Z")
[QUOTE=dfreeman87] Why can’t my rectum flip inside out and back again every time I make a bowel movement? [/QUOTE] It’s a good thing it can’t because they’d always be gettin’ screwed up when you’re a teenager. Can you imagine the fun a bunch of teenage boys would have sitting around and flipping their rectums in and out? That’s tailor-made hilarity for them. Sooner or later though someone’s going to step on one or shoot it with a BB gun or something and widespread rectum failure will ensue. Rectum flipping just sounds like an accident waiting to happen. ---
**Author:** ![Bob55](https://avatars.discourse-cdn.com/v4/letter/b/e9c0ed/32.png) [@Bob55](https://boards.straightdope.com/u/Bob55)\ **Post date:** [July 16, 2008, 6:52pm UTC](https://boards.straightdope.com/t/the-non-evolution-of-the-human-anus/456605/44 "2008-07-16T18:52:26Z")
[QUOTE=Qadgop the Mercotan] It’s the modern human diet. It is not conducive to neatly formed, solid stools that pop out with nary a skid. Either go back to a hunter-gatherer diet, or cultivate an opiate habit. Just don’t overdo on the opiates or you’ll have to go excavating to get it out. Or find the right mix of fresh foods with adequate fiber content. Me, I favor a bidet. [/QUOTE] I second this. Have you ever gone on a diet and eaten what you’re supposed to? You’ll have a bowel movement like once every 3 days, and when you do it’s pretty solid and clean…but I think the grease in all of our food doesn’t help things. So it probably wasn’t as much of an issue in the past as it is today. ---
**Author:** ![Fear\_Itself](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fear_itself/32/19637_2.png) [@Fear\_Itself](https://boards.straightdope.com/u/Fear_Itself)\ **Post date:** [July 16, 2008, 7:00pm UTC](https://boards.straightdope.com/t/the-non-evolution-of-the-human-anus/456605/45 "2008-07-16T19:00:45Z")
[QUOTE=Bob55] I second this. Have you ever gone on a diet and eaten what you’re supposed to? You’ll have a bowel movement like once every 3 days, and when you do it’s pretty solid and clean… [/QUOTE] Eating lots of fruits and vegetables usually results in more frequent bowel movements, with a softer stool. What diet are you referring to? ---
**Author:** ![Cervaise](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cervaise/32/16693_2.png) [@Cervaise](https://boards.straightdope.com/u/Cervaise)\ **Post date:** [July 16, 2008, 7:06pm UTC](https://boards.straightdope.com/t/the-non-evolution-of-the-human-anus/456605/46 "2008-07-16T19:06:43Z")
[QUOTE=dfreeman87] Why do I have to wipe my ass? [/QUOTE] Because it’s got shit all over it. Duh. More serious answer: [QUOTE=Colophon] Thing is, there’s no real evolutionary pressure for a better design. It does the job, and we have hands that can reach to clean up. It might cause a bit of irritation, but nothing that will stop us from passing our genes (including those for baboon arse) along to the next generation. [/QUOTE] This is right. Evolution is poorly understood by the mainstream; it’s generally held to mean “making improvements in succeeding generations,” so we get questions like this one, or “why do we get cataracts when we get old, wouldn’t evolution fix that” or “why do we go bald when we get old” and so on. That’s not how evolution works. Evolution’s improvements are _solely_ focused on “making more successful and/or greater numbers of _offspring._” Period. A species that does that will spread. A species that makes fewer and/or less successful offspring will not. That’s it. All the rest of this discussion, about the imperfect design of the buttocks, and the way diet affects the consistency of one’s feces, is more or less academic (insofar as a discussion of assholes and shit can be academic). There is no evolutionary pressure to fix cataracts, or baldness, or the baboon ass, because they have zero to do with reproduction. If you can make babies, it doesn’t matter how clean or how foul your anus might be. Hence, your shitty, shitty ass. Now clean it up! 😃 ---
**Author:** ![Baldwin](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/baldwin/32/7264_2.png) [@Baldwin](https://boards.straightdope.com/u/Baldwin)\ **Post date:** [July 16, 2008, 7:07pm UTC](https://boards.straightdope.com/t/the-non-evolution-of-the-human-anus/456605/47 "2008-07-16T19:07:18Z")
[QUOTE=mr. jp] Man is the only animal that flushes - or needs to. [/QUOTE] That’s got to be one of the best _bon mots_ I’ve encountered in ten years of the SDMB, which is saying something. As for the anus-related issues; that’s something we need to address as soon as we’ve got a handle on genetic engineering. The world will be inherited by a generation of Uber-men with superhuman anal capabilities. ---
**Author:** ![Scumpup](https://avatars.discourse-cdn.com/v4/letter/s/ce73a5/32.png) [@Scumpup](https://boards.straightdope.com/u/Scumpup)\ **Post date:** [July 16, 2008, 7:22pm UTC](https://boards.straightdope.com/t/the-non-evolution-of-the-human-anus/456605/48 "2008-07-16T19:22:43Z")
[QUOTE=Baldwin] As for the anus-related issues; that’s something we need to address as soon as we’ve got a handle on genetic engineering. The world will be inherited by a generation of Uber-men with superhuman anal capabilities. [/QUOTE] Do you suppose they will look back on Richard Gere as their spiritual father? ---
**Author:** ![Fantome](https://avatars.discourse-cdn.com/v4/letter/f/e9c0ed/32.png) [@Fantome](https://boards.straightdope.com/u/Fantome)\ **Post date:** [July 16, 2008, 7:31pm UTC](https://boards.straightdope.com/t/the-non-evolution-of-the-human-anus/456605/49 "2008-07-16T19:31:26Z")
[QUOTE=Qadgop the Mercotan] It’s the modern human diet. It is not conducive to neatly formed, solid stools that pop out with nary a skid. Either go back to a hunter-gatherer diet, or cultivate an opiate habit. Just don’t overdo on the opiates or you’ll have to go excavating to get it out. Or find the right mix of fresh foods with adequate fiber content. Me, I favor a bidet. [/QUOTE] You’re saying a high fiber diet will lessen the need for wiping? That doesn’t sound right to me. Most sources (one being [mayoclinic.com](http://mayoclinic.com)) claim that a high fiber diet will soften stool. That sounds like more skid marks to me. ---
**Author:** ![dogbutler](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dogbutler/32/428_2.png) [@dogbutler](https://boards.straightdope.com/u/dogbutler)\ **Post date:** [July 16, 2008, 7:48pm UTC](https://boards.straightdope.com/t/the-non-evolution-of-the-human-anus/456605/50 "2008-07-16T19:48:21Z")
[QUOTE=Scumpup] Do you suppose they will look back on Richard Gere as their spiritual father? [/QUOTE] Yes, and it will also result in the extinction of the whole of the Rodentia order. ---
**Author:** ![Yllaria](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/yllaria/32/3452_2.png) [@Yllaria](https://boards.straightdope.com/u/Yllaria)\ **Post date:** [July 16, 2008, 8:44pm UTC](https://boards.straightdope.com/t/the-non-evolution-of-the-human-anus/456605/51 "2008-07-16T20:44:24Z")
[QUOTE=lieu] It’s a good thing it can’t because they’d always be gettin’ screwed up when you’re a teenager. Can you imagine the fun a bunch of teenage boys would have sitting around and flipping their rectums in and out? That’s tailor-made hilarity for them. Sooner or later though someone’s going to step on one or shoot it with a BB gun or something and widespread rectum failure will ensue. Rectum flipping just sounds like an accident waiting to happen. [/QUOTE] You know human nature too well. As to how evolutionary pressure works, well, if your shitty ass keeps you from getting laid, you’ll be selected out. Otherwise, you’re in. So to speak. You’re also out if it kills you before you reproduce. Survival of the survivors. ---
**Author:** ![Terminus\_Est](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/terminus_est/32/3087_2.png) [@Terminus\_Est](https://boards.straightdope.com/u/Terminus_Est)\ **Post date:** [July 16, 2008, 8:59pm UTC](https://boards.straightdope.com/t/the-non-evolution-of-the-human-anus/456605/52 "2008-07-16T20:59:38Z")
[QUOTE=Fantome] You’re saying a high fiber diet will lessen the need for wiping? That doesn’t sound right to me. Most sources (one being [mayoclinic.com](http://mayoclinic.com)) claim that a high fiber diet will soften stool. That sounds like more skid marks to me. [/QUOTE] This is very easily tested. Try taking Metamucil regularly. You’ll find that you’ll be using less toilet paper. Sometimes your asshole will be so clean that the first wipe will show nothing at all. Speak from experience? Who, me? ---
**Author:** ![dfreeman87](https://avatars.discourse-cdn.com/v4/letter/d/d78d45/32.png) [@dfreeman87](https://boards.straightdope.com/u/dfreeman87)\ **Post date:** [July 16, 2008, 9:19pm UTC](https://boards.straightdope.com/t/the-non-evolution-of-the-human-anus/456605/53 "2008-07-16T21:19:21Z")
[QUOTE=Cervaise] Because it’s got shit all over it. Duh. More serious answer:This is right. Evolution is poorly understood by the mainstream; it’s generally held to mean “making improvements in succeeding generations,” so we get questions like this one, or “why do we get cataracts when we get old, wouldn’t evolution fix that” or “why do we go bald when we get old” and so on. That’s not how evolution works. Evolution’s improvements are _solely_ focused on “making more successful and/or greater numbers of _offspring._” Period. A species that does that will spread. A species that makes fewer and/or less successful offspring will not. That’s it. All the rest of this discussion, about the imperfect design of the buttocks, and the way diet affects the consistency of one’s feces, is more or less academic (insofar as a discussion of assholes and shit can be academic). There is no evolutionary pressure to fix cataracts, or baldness, or the baboon ass, because they have zero to do with reproduction. If you can make babies, it doesn’t matter how clean or how foul your anus might be. Hence, your shitty, shitty ass. Now clean it up! 😃 [/QUOTE] Actually, I have a rather thorough understanding of evolution and evolutionary pressures. That aside, perhaps I need to get a little more specific with the question. If my earlier assumption is correct, and I do realize that it’s an “if”, the problem of wiping came about as a result of bipedalism. Depending on who you talk to, bipedalism developed between 3 and 4 million years ago, give or take. Now, I’m not too sure when Charmin Extra Soft hit the scene, but I believe it was a bit later. (Or Cottonelle if you prefer) In any case, I can’t imagine that all bipedal hominids of the time intinctively knew to perform a butt scoot or find a leaf and perfrom the correct motion. However, I do imagine that the moment one of our furry ancestors began to stand up full time (as well as develope the gluteal muscles), the baboon ass quandry came to front. And, if you’ve ever had baboon ass, you would know that it can actually become quite debilatating, if not simply annoying. Either of the previous would make any jungle or savannah dwelling creature much more likely to end up lunch for some larger swifter animal. So I guess the question in the end is, why did nature choose the guy who had crap all over his ass until he decided to wipe instead of guy that had superior rectal control. :dubious: ---
**Author:** ![dfreeman87](https://avatars.discourse-cdn.com/v4/letter/d/d78d45/32.png) [@dfreeman87](https://boards.straightdope.com/u/dfreeman87)\ **Post date:** [July 16, 2008, 9:39pm UTC](https://boards.straightdope.com/t/the-non-evolution-of-the-human-anus/456605/54 "2008-07-16T21:39:22Z")
And for all you picky people, by “nature”, I do mean what pressure was there to develope proper ass wiping technique in stead of the “push harder to make your rectum flip inside out and back again technique.” ---
**Author:** ![Fantome](https://avatars.discourse-cdn.com/v4/letter/f/e9c0ed/32.png) [@Fantome](https://boards.straightdope.com/u/Fantome)\ **Post date:** [July 16, 2008, 9:41pm UTC](https://boards.straightdope.com/t/the-non-evolution-of-the-human-anus/456605/55 "2008-07-16T21:41:11Z")
[QUOTE=Terminus Est] This is very easily tested. Try taking Metamucil regularly. You’ll find that you’ll be using less toilet paper. Sometimes your asshole will be so clean that the first wipe will show nothing at all. Speak from experience? Who, me? [/QUOTE] Well, I get plenty of fiber and go regularly, so I’m not into trying the Metamucil experiment. When I used to have a more processed diet as a bachelor, I would crap more firm and some wipes left nothing on the paper. Now that I’m married and I eat oatmeal in the mornings, salads with dinner, etc., I need to wipe much more. This reflects what I read on the Mayo clinic’s website and not what Qadgop said. I Googled "high fiber wipe toilet paper, and I found an article on wiping where someone made a comment similar to Qadgop’s: > [@](#): > > It’s funny, but wiping your privates is far less (note: LESS not NOT) necessary in Hunter gatherer societies, as their high fiber, high protein, low carbohydrate diet tends to make their ‘business’ more like animal droppings, and less soft. Not only have I always had docs tell me the opposite (more fiber, more soft), but my own experiences have confirmed it for me. From [GIcare.com](http://GIcare.com): > [@](#): > > A high-fiber diet causes a large, soft, bulky stool that passes through the bowel easily and quickly. Because of this action, some digestive tract disorders may be avoided, halted, or even reversed simply by following a high-fiber diet. A softer, larger stool helps prevent constipation and straining. ---
**Author:** ![x-ray\_vision](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/x-ray_vision/32/351_2.png) [@x-ray\_vision](https://boards.straightdope.com/u/x-ray_vision)\ **Post date:** [July 16, 2008, 9:58pm UTC](https://boards.straightdope.com/t/the-non-evolution-of-the-human-anus/456605/56 "2008-07-16T21:58:27Z")
I just asked my wife (an NP that works for a GI office) about high fiber and heavy wiping vs. light wiping. She tells me that a high fiber diet with adequate fluid intake (recommended) will result in soft, fluffy stools usually requiring more wiping. A high fiber diet with inadequate fluid intake (not recommended) will result in hard, cement-like stools usually requiring less wiping. ---
**Author:** ![Telemark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/telemark/32/372_2.png) [@Telemark](https://boards.straightdope.com/u/Telemark)\ **Post date:** [July 16, 2008, 10:35pm UTC](https://boards.straightdope.com/t/the-non-evolution-of-the-human-anus/456605/57 "2008-07-16T22:35:07Z")
[QUOTE=dfreeman87] So I guess the question in the end is, why did nature choose the guy who had crap all over his ass until he decided to wipe instead of guy that had superior rectal control. :dubious: [/QUOTE] Because the latter fellow never showed up. Not all mutations will occur. ---
**Author:** ![Qadgop\_the\_Mercotan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/qadgop_the_mercotan/32/83_2.png) [@Qadgop\_the\_Mercotan](https://boards.straightdope.com/u/Qadgop_the_Mercotan)\ **Post date:** [July 16, 2008, 10:44pm UTC](https://boards.straightdope.com/t/the-non-evolution-of-the-human-anus/456605/58 "2008-07-16T22:44:26Z")
[QUOTE=Fantome] Not only have I always had docs tell me the opposite (more fiber, more soft), but my own experiences have confirmed it for me. [/QUOTE] Mix high fiber with high protein and low carbs to achieve the desired effect. Fiber in itself is very versatile. It firms up loose stools, and softens up the stools that are too hard. So I end up recommending it for patients who have either diarrhea or constipation. Again, balance is what is needed. ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [July 16, 2008, 11:09pm UTC](https://boards.straightdope.com/t/the-non-evolution-of-the-human-anus/456605/59 "2008-07-16T23:09:53Z")
Well, I’ve never been able to correlate my diet with those mystical “No-Wipe Dumps”. If I could, I’d eat whatever it was all the time, as there’s no better feeling than an NWD! As it is, I just look on them as occasional gifts from a benevolent higher being, with no rhyme or reason to their occurrence. (Although I will wager that Guinness is _not_ part of the NWD diet 😃 ) ---
**Author:** ![lieu](https://avatars.discourse-cdn.com/v4/letter/l/c2a13f/32.png) [@lieu](https://boards.straightdope.com/u/lieu)\ **Post date:** [July 17, 2008, 2:54am UTC](https://boards.straightdope.com/t/the-non-evolution-of-the-human-anus/456605/60 "2008-07-17T02:54:53Z")
[QUOTE=x-ray vision] … soft, fluffy stools … [/QUOTE] I feel like some lost tribe Amazonian whisked from the jungle and placed by the TV store display window. _Points finger_ Those things really exist? You can take a nerf? [Previous page](https://boards.straightdope.com/t/the-non-evolution-of-the-human-anus/456605.md?page=2) [Next page](https://boards.straightdope.com/t/the-non-evolution-of-the-human-anus/456605.md?page=4)