Why do we have butt hair?

+51 votes
asked Aug 5 in Science by Travis (970 points)
edited Aug 8
Why do we have butt hair? This issue is a very serious one. Having it on my genitals seems quite understandable to keep the little guys all warm, but what benefits can I possibly derive from having hairs in my butt? To me, it is a kind of hygiene hazard that comes with no known benefit.

3 Answers

+21 votes
answered Aug 10 by Virag (680 points)
edited Aug 14

Two things should be mentioned first:

  1. Butt hair is not common in everyone, but it runs in some lineages.
  2. The human body was never wired for convenience. It might be some odd evolutionary addition that was never really removed, something that was once of benefit, but as we evolved, it became quite useless just like the appendix.

The original function of butt hair is protection. You must never forget that every hole in your body-including your butthole are quite sensitive. So like every other sensitive hole in your body, there is a need to protect your butthole. At our current evolutionary position, we stand upward in a straight posture. In this straight posture, the muscles for sitting convenience completely fold behind it, giving it all the protection it requires as long as we ensure it is clean. But before we acquired this posture, we would have ended up with a posture like that of the gorilla. Try to bend over when your pants are off your ass. You will discover that the both sides of gluteous maximus are no longer completely sealed. So imagine you are in that position at all times, everyday.

If this were to be the case, you would have had your butthole exposed to open air, sun, and even parasites. Having hairs in your asshole in such circumstances would make the hair a kind of insulator and sunblock and prevent the small critters you hate having around that little hole from making it their permanent residence. 

+5 votes
answered Aug 7 by Chloe (900 points)
edited Aug 7
I'm one of those people with alopecia universalis - no hair anywhere. I would say you have hair in your butthole because you descended from a very hairy primate.

I do not have any hair on my ass which I think is quite great because I wipe my ass clean in 2 or 3 wipes only. When compared to when I used to have some ass hair, I often wiped up to 10 or 12 wipes before I could get my ass cleaned up completely. This is the best part of living with this kind of auto immune issue.

The most sucking part is that I have neither nose hair nor eyebrows/eyelashes so one can easily mistake me for someone undergoing chemotherapy.

The friction argument sounds to me like bullshit. My skin is quite sensitive, and honestly, since all my body hair vanished, engaging in exercises has become easier and more fun. I no longer experience anything like chaffing or the likes in my armpits, groin, or ass after a 10k's run. Conclusively, body hair, to me has been a very useless thing to keep.
commented Mar 31, 2015 by Nena (650 points)
So envy you because you don't need to ask the question(why do we have butt hair)
+5 votes
answered Aug 12 by Alice (430 points)
edited Aug 13
It eases friction. Any part of you that rubs together such as your crotch, armpits, and ass crack has some hairs to prevent skin blistering.
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