# Butt hair **URL:** \ **Category:** Factual Questions\ **Created:** [June 20, 2011, 11:01am UTC](https://boards.straightdope.com/t/butt-hair/586134 "2011-06-20T11:01:38Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![CheeseDonkey](https://avatars.discourse-cdn.com/v4/letter/c/ecae2f/32.png) [@CheeseDonkey](https://boards.straightdope.com/u/CheeseDonkey)\ **Post date:** [June 20, 2011, 11:01am UTC](https://boards.straightdope.com/t/butt-hair/586134/1 "2011-06-20T11:01:38Z")
What is the reason we (or some of us, men mostly it seems) have butt hair? What biological purpose does it serve? It mostly serves as an annoyance, in my humble opinion (stupid dingleberries get caught in it every once in a while.) ---
**Author:** ![chaoticbear](https://avatars.discourse-cdn.com/v4/letter/c/f07891/32.png) [@chaoticbear](https://boards.straightdope.com/u/chaoticbear)\ **Post date:** [June 20, 2011, 11:18am UTC](https://boards.straightdope.com/t/butt-hair/586134/2 "2011-06-20T11:18:16Z")
Insulation! Don’t want to get the asshole cold, you know 😉 (I assume it’s the same reason other animals do - because it’s skin and skin grows hair.) ---
**Author:** ![dolphinboy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dolphinboy/32/330_2.png) [@dolphinboy](https://boards.straightdope.com/u/dolphinboy)\ **Post date:** [June 20, 2011, 2:07pm UTC](https://boards.straightdope.com/t/butt-hair/586134/3 "2011-06-20T14:07:03Z")
A better question might be why doesn’t everyone have copious amounts of body hair anymore. Go to any natural history museum and you will likely see a scene showing our cave dwelling ancestors with lots of body hair. Presumably, over the millennia the lack of body hair hasn’t been a reproductive disadvantage. But in general, hair provides warmth for most mammals (Cetaceans excluded because they evolved blubber instead), but once humans started wearing “clothing” the need for hair wasn’t as important. ---
**Author:** ![panache45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/panache45/32/64_2.png) [@panache45](https://boards.straightdope.com/u/panache45)\ **Post date:** [June 20, 2011, 2:39pm UTC](https://boards.straightdope.com/t/butt-hair/586134/4 "2011-06-20T14:39:55Z")
The only reason you have butt hair is that your ancestors had butt hair, and it didn’t prevent them from reproducing. Why does there need to be a “biological purpose”? That’s not how evolution works. ---
**Author:** ![Dingbang](https://avatars.discourse-cdn.com/v4/letter/d/ac8455/32.png) [@Dingbang](https://boards.straightdope.com/u/Dingbang)\ **Post date:** [June 20, 2011, 3:20pm UTC](https://boards.straightdope.com/t/butt-hair/586134/5 "2011-06-20T15:20:45Z")
> [@panache45](#): > > The only reason you have butt hair is that your ancestors had butt hair, and it didn’t prevent them from reproducing. Why does there need to be a “biological purpose”? That’s not how evolution works. Well said. There are so many of these “Why do we have …” questions that it seems people think evolution has fantastically engineered the human body from scratch to be 100% efficient and without extraneous parts. Uh uh. Evolution usually gets rid of stuff that interfere with our species’ survival, but it’s completely backwards to think that evolution designed the human body from nothing and said “Hmm, does this animal need butt hair? I think so, because it will be useful in X way. Therefore, I will give it butt hair.” It’s just there because it is. It doesn’t have to serve any useful purpose at all. ---
**Author:** ![Clark\_Cello](https://avatars.discourse-cdn.com/v4/letter/c/58f4c7/32.png) [@Clark\_Cello](https://boards.straightdope.com/u/Clark_Cello)\ **Post date:** [June 20, 2011, 3:33pm UTC](https://boards.straightdope.com/t/butt-hair/586134/6 "2011-06-20T15:33:53Z")
> [@panache45](#): > > The only reason you have butt hair is that your ancestors had butt hair, and **it didn’t prevent them from reproducing**. Why does there need to be a “biological purpose”? That’s not how evolution works. Well, it doesn’t help, let me tell you. ---
**Author:** ![Spiff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/spiff/32/9852_2.png) [@Spiff](https://boards.straightdope.com/u/Spiff)\ **Post date:** [June 20, 2011, 3:56pm UTC](https://boards.straightdope.com/t/butt-hair/586134/7 "2011-06-20T15:56:32Z")
> [@CheeseDonkey](#): > > What is the reason we (or some of us, men mostly it seems) have butt hair? What biological purpose does it serve? > > It mostly serves as an annoyance, in my humble opinion (stupid dingleberries get caught in it every once in a while.) TMI: [spoiler]To rid myself of the dingleberry issue, I trimmed my butt hair off using the mustache/sideburns trimmer on an electric razor. Solved the dingleberry issue, but I had chapped cheeks for a few weeks until the butt hair grew back. The chapped cheeks were NOT due to razor burns, but rather the increased moisture trapped back there. It seems that butt hairs are very good at giving the butt cheeks a wee bit of separation, just enough to get some very important airflow back there.[/spoiler] ---
**Author:** ![chaoticbear](https://avatars.discourse-cdn.com/v4/letter/c/f07891/32.png) [@chaoticbear](https://boards.straightdope.com/u/chaoticbear)\ **Post date:** [June 20, 2011, 4:14pm UTC](https://boards.straightdope.com/t/butt-hair/586134/8 "2011-06-20T16:14:17Z")
This is the obligatory ass-hair shaving story, in case someone hasn’t read it. ---
**Author:** ![ZipperJJ](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/zipperjj/32/211_2.png) [@ZipperJJ](https://boards.straightdope.com/u/ZipperJJ)\ **Post date:** [June 20, 2011, 5:38pm UTC](https://boards.straightdope.com/t/butt-hair/586134/9 "2011-06-20T17:38:05Z")
Personally, I’ve always assumed that butt, genital and armpit hair was to keep skin from rubbing against skin all the time. I think of it as a lubricant, but not a liquid lubricant more in the sense that graphite is a lubricant. I have very sensitive skin and personally if I do not have a bit of hair in those areas (not that I’ve tried to shave off my butt hair…) I get a rash within a few hours from skin-on-skin or clothing-on-skin rubbing. ---
**Author:** ![Knorf](https://avatars.discourse-cdn.com/v4/letter/k/58956e/32.png) [@Knorf](https://boards.straightdope.com/u/Knorf)\ **Post date:** [June 20, 2011, 5:44pm UTC](https://boards.straightdope.com/t/butt-hair/586134/10 "2011-06-20T17:44:22Z")
> [@Dingbang](#): > > There are so many of these “Why do we have …” questions that it seems people think evolution has fantastically engineered the human body from scratch to be 100% efficient and without extraneous parts. IMO, it’s a legacy of creationist thinking. With an intelligent designer, you expect everything to be placed with a purpose. Someone had to decide to put it there, so there must have been a reason, right? The legacy of body parts/features that are of dubious utility at best was an early pointer to natural selection. ---
**Author:** ![brittekland](https://avatars.discourse-cdn.com/v4/letter/b/aeb1de/32.png) [@brittekland](https://boards.straightdope.com/u/brittekland)\ **Post date:** [June 20, 2011, 5:48pm UTC](https://boards.straightdope.com/t/butt-hair/586134/11 "2011-06-20T17:48:31Z")
> [@Knorf](#): > > The legacy of body parts/features that are of dubious utility at best was an early pointer to natural selection. A creation in progress. ---
**Author:** ![dracoi](https://avatars.discourse-cdn.com/v4/letter/d/90db22/32.png) [@dracoi](https://boards.straightdope.com/u/dracoi)\ **Post date:** [June 20, 2011, 6:41pm UTC](https://boards.straightdope.com/t/butt-hair/586134/12 "2011-06-20T18:41:05Z")
> [@Knorf](#): > > IMO, it’s a legacy of creationist thinking. With an intelligent designer, you expect everything to be placed with a purpose. Someone had to decide to put it there, so there must have been a reason, right? > > The legacy of body parts/features that are of dubious utility at best was an early pointer to natural selection. I don’t think you can make this about creationism - it’s just an outgrowth of how people think. We look at a heart and see a clear purpose. Hands, eyes, nose, etc. It’s hard to find body parts without a clear purpose/function. The “logical” conclusion is to then seek a purpose for every anatomical feature. While it may not always be right, this behavior is actually useful. By assuming a function and looking for the answer, we sometimes discover new knowledge. ---
**Author:** ![SanDiegoTim](https://avatars.discourse-cdn.com/v4/letter/s/85e7bf/32.png) [@SanDiegoTim](https://boards.straightdope.com/u/SanDiegoTim)\ **Post date:** [June 20, 2011, 7:35pm UTC](https://boards.straightdope.com/t/butt-hair/586134/13 "2011-06-20T19:35:28Z")
Without butt hair would dingleberries exist? ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [June 22, 2011, 8:49pm UTC](https://boards.straightdope.com/t/butt-hair/586134/14 "2011-06-22T20:49:25Z")
Don’t porn women (and others, for all I know) get their asshole and adjoining suburbs waxed? I once saw Sarah Silverman zing some playmates at a Hugh Hefner roast with that. By Internet visual inspection it seems to hold. ---
**Author:** ![Chessic\_Sense](https://avatars.discourse-cdn.com/v4/letter/c/7c8e57/32.png) [@Chessic\_Sense](https://boards.straightdope.com/u/Chessic_Sense)\ **Post date:** [June 22, 2011, 9:05pm UTC](https://boards.straightdope.com/t/butt-hair/586134/15 "2011-06-22T21:05:21Z")
I’m surprised no one has mentioned the obvious “because it’s an entry” reason. Ear hair, eyelashes, mustaches, throat cilia…all there to prevent dust, germs, and other baddies from getting past the hardest working immune system component you’ve got- your skin. ---
**Author:** ![mr.jp](https://avatars.discourse-cdn.com/v4/letter/m/48db29/32.png) [@mr.jp](https://boards.straightdope.com/u/mr.jp)\ **Post date:** [June 22, 2011, 10:04pm UTC](https://boards.straightdope.com/t/butt-hair/586134/16 "2011-06-22T22:04:55Z")
I think you people are underestimating how effective evolution can be. Growing hair has a cost. If there is no advantage to it at all, people with hair would pay that cost, while people without wouldn’t. They would thus have a little less resources for other things, such as surviving and having children. Even if this disadvantage is very small, it accumulates over generations, and humans have existed for a lot of generations. There’s nothing creationist about expecting our features to be somewhat optimized. It is a straightforward evolutionary line of thought. ---
**Author:** ![Knorf](https://avatars.discourse-cdn.com/v4/letter/k/58956e/32.png) [@Knorf](https://boards.straightdope.com/u/Knorf)\ **Post date:** [June 22, 2011, 11:12pm UTC](https://boards.straightdope.com/t/butt-hair/586134/17 "2011-06-22T23:12:07Z")
> [@mr.jp](#): > > I think you people are underestimating how effective evolution can be. Growing hair has a cost. If there is no advantage to it at all, people with hair would pay that cost, while people without wouldn’t. They would thus have a little less resources for other things, such as surviving and having children. Even if this disadvantage is very small, it accumulates over generations, and humans have existed for a lot of generations. There’s nothing creationist about expecting our features to be somewhat optimized. It is a straightforward evolutionary line of thought. That’s really not how evolution works. ---
**Author:** ![mr.jp](https://avatars.discourse-cdn.com/v4/letter/m/48db29/32.png) [@mr.jp](https://boards.straightdope.com/u/mr.jp)\ **Post date:** [June 23, 2011, 12:00am UTC](https://boards.straightdope.com/t/butt-hair/586134/18 "2011-06-23T00:00:32Z")
> [@Knorf](#): > > That’s really not how evolution works. What kind of an argument is this? A mutation cause a small increase or decrease in fitness. This small fitness advantages / disadvantages will over time cause the mutation to increase / decrease in frequency in the population. This is _exactly_ how evolution works. ---
**Author:** ![panache45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/panache45/32/64_2.png) [@panache45](https://boards.straightdope.com/u/panache45)\ **Post date:** [June 23, 2011, 12:20am UTC](https://boards.straightdope.com/t/butt-hair/586134/19 "2011-06-23T00:20:51Z")
> [@mr.jp](#): > > What kind of an argument is this? > > A mutation cause a small increase or decrease in fitness. This small fitness advantages / disadvantages will over time cause the mutation to increase / decrease in frequency in the population. This is _exactly_ how evolution works. No, it’s not. The “fitness advantages/disadvantages” still need to have an effect on reproduction. ---
**Author:** ![yoyodyne](https://avatars.discourse-cdn.com/v4/letter/y/a9a28c/32.png) [@yoyodyne](https://boards.straightdope.com/u/yoyodyne)\ **Post date:** [June 23, 2011, 12:23am UTC](https://boards.straightdope.com/t/butt-hair/586134/20 "2011-06-23T00:23:33Z")
> [@Chessic\_Sense](#): > > I’m surprised no one has mentioned the obvious “because it’s an entry” reason. Ear hair, eyelashes, mustaches, throat cilia…all there to prevent dust, germs, and other baddies from getting past the hardest working immune system component you’ve got- your skin. Mine’s an exit, thank you! bah-da-bump [Next page](https://boards.straightdope.com/t/butt-hair/586134.md?page=2)