# Why is the scrotum wrinkly and hairy? **URL:** \ **Category:** Factual Questions\ **Created:** [May 1, 2014, 5:48am UTC](https://boards.straightdope.com/t/why-is-the-scrotum-wrinkly-and-hairy/687423 "2014-05-01T05:48:10Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Cardboard](https://avatars.discourse-cdn.com/v4/letter/c/49beb7/32.png) [@Cardboard](https://boards.straightdope.com/u/Cardboard)\ **Post date:** [May 1, 2014, 5:48am UTC](https://boards.straightdope.com/t/why-is-the-scrotum-wrinkly-and-hairy/687423/1 "2014-05-01T05:48:10Z")
Why is the scrotum wrinkly and hairy? ---
**Author:** ![sitchensis](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sitchensis/32/4892_2.png) [@sitchensis](https://boards.straightdope.com/u/sitchensis)\ **Post date:** [May 1, 2014, 5:53am UTC](https://boards.straightdope.com/t/why-is-the-scrotum-wrinkly-and-hairy/687423/2 "2014-05-01T05:53:57Z")
It has to expand and contract to keep the testis at an optimum temperature to produce sperm. ---
**Author:** ![Manduck](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/manduck/32/256_2.png) [@Manduck](https://boards.straightdope.com/u/Manduck)\ **Post date:** [May 1, 2014, 6:36am UTC](https://boards.straightdope.com/t/why-is-the-scrotum-wrinkly-and-hairy/687423/3 "2014-05-01T06:36:26Z")
… and it’s hairy because it has hair on it. ---
**Author:** ![buddha\_david](https://avatars.discourse-cdn.com/v4/letter/b/ee7513/32.png) [@buddha\_david](https://boards.straightdope.com/u/buddha_david)\ **Post date:** [May 1, 2014, 6:46am UTC](https://boards.straightdope.com/t/why-is-the-scrotum-wrinkly-and-hairy/687423/4 "2014-05-01T06:46:17Z")
Asking this question must have taken a lot of… …no, I can’t do it, too easy. 🆒 ---
**Author:** ![zoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/zoid/32/336_2.png) [@zoid](https://boards.straightdope.com/u/zoid)\ **Post date:** [May 1, 2014, 6:51am UTC](https://boards.straightdope.com/t/why-is-the-scrotum-wrinkly-and-hairy/687423/5 "2014-05-01T06:51:32Z")
Because if it was smooth and white it would be an aspirin. ---
**Author:** ![randompattern](https://avatars.discourse-cdn.com/v4/letter/r/7993a0/32.png) [@randompattern](https://boards.straightdope.com/u/randompattern)\ **Post date:** [May 1, 2014, 7:00am UTC](https://boards.straightdope.com/t/why-is-the-scrotum-wrinkly-and-hairy/687423/6 "2014-05-01T07:00:24Z")
They are? ---
**Author:** ![Little\_Pig](https://avatars.discourse-cdn.com/v4/letter/l/c57346/32.png) [@Little\_Pig](https://boards.straightdope.com/u/Little_Pig)\ **Post date:** [May 1, 2014, 7:23am UTC](https://boards.straightdope.com/t/why-is-the-scrotum-wrinkly-and-hairy/687423/7 "2014-05-01T07:23:56Z")
Its because it doesn’t get out more. ---
**Author:** ![Wakinyan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wakinyan/32/352_2.png) [@Wakinyan](https://boards.straightdope.com/u/Wakinyan)\ **Post date:** [May 1, 2014, 8:23am UTC](https://boards.straightdope.com/t/why-is-the-scrotum-wrinkly-and-hairy/687423/8 "2014-05-01T08:23:37Z")
Cecil has written about the hairy part, [here](http://www.straightdope.com/columns/read/54/whats-the-purpose-of-pubic-hair). ---
**Author:** ![aceplace57](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aceplace57/32/3500_2.png) [@aceplace57](https://boards.straightdope.com/u/aceplace57)\ **Post date:** [May 1, 2014, 9:19am UTC](https://boards.straightdope.com/t/why-is-the-scrotum-wrinkly-and-hairy/687423/9 "2014-05-01T09:19:15Z")
If girls fondle them long enough they get smooth and silky. Thats the story I told my beloved 30 years ago and I’m sticking to it. 😃 ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [May 1, 2014, 11:45am UTC](https://boards.straightdope.com/t/why-is-the-scrotum-wrinkly-and-hairy/687423/10 "2014-05-01T11:45:31Z")
> [@Cardboard](#): > > Why is the scrotum wrinkly and hairy? Thermal management. As **sitchensis** suggests, there is an optimal temperature for sperm production. Scrotal skin tenses and relaxes in accordance with temperature. You can see this happening in certain situations: -sit or lie as still as possible and just watch your scrotum. You’ll see areas of skin slowly contracting or relaxing, responding to minor temperature variations. -Spend ten minutes in a hot bath. Get out, and observe that your scrotum is completely relaxed, hanging as low as possible. It’s too hot, and your scrotum is trying to maximize surface area in order to dump heat. Obviously this isn’t helpful while submerged in hot water, but your scrotum doesn’t realize this (and it works pretty well once you get out). -Spend ten minutes in cold water, or go for a long walk on a very cold winter day. Or if you’re bold/impatient, apply an ice pack directly to your scrotum. Observe that your scrotum contracts tightly up againts your body. It’s too cold, and it’s trying to minimize surface area in order to restrict heat loss. ---
**Author:** ![VunderBob](https://avatars.discourse-cdn.com/v4/letter/v/839c29/32.png) [@VunderBob](https://boards.straightdope.com/u/VunderBob)\ **Post date:** [May 1, 2014, 11:50am UTC](https://boards.straightdope.com/t/why-is-the-scrotum-wrinkly-and-hairy/687423/11 "2014-05-01T11:50:05Z")
> [@Machine\_Elf](#): > > Thermal management. As **sitchensis** suggests, there is an optimal temperature for sperm production. Scrotal skin tenses and relaxes in accordance with temperature. You can see this happening in certain situations: > > [snip] > > -Spend ten minutes in a hot bath. Get out, and observe that your scrotum is completely relaxed, hanging as low as possible. It’s too hot, and your scrotum is trying to maximize surface area in order to dump heat. Obviously this isn’t helpful while submerged in hot water, but your scrotum doesn’t realize this (and it works pretty well once you get out). You’re saying, if your hands are cold, you should cover your balls? ---
**Author:** ![Zapp\_S](https://avatars.discourse-cdn.com/v4/letter/z/ee59a6/32.png) [@Zapp\_S](https://boards.straightdope.com/u/Zapp_S)\ **Post date:** [May 1, 2014, 11:54am UTC](https://boards.straightdope.com/t/why-is-the-scrotum-wrinkly-and-hairy/687423/12 "2014-05-01T11:54:55Z")
> [@Machine\_Elf](#): > > -Spend ten minutes in a hot bath. Get out, and observe that your scrotum is completely relaxed, hanging as low as possible. It’s too hot, and your scrotum is trying to maximize surface area in order to dump heat. Obviously this isn’t helpful while submerged in hot water, but your scrotum doesn’t realize this (and it works pretty well once you get out). > > -Spend ten minutes in cold water, or go for a long walk on a very cold winter day. Or if you’re bold/impatient, apply an ice pack directly to your scrotum. Observe that your scrotum contracts tightly up againts your body. It’s too cold, and it’s trying to minimize surface area in order to restrict heat loss. It is not only surface area, but also distance from the trunk where body heat is generated. ---
**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:** [May 1, 2014, 12:57pm UTC](https://boards.straightdope.com/t/why-is-the-scrotum-wrinkly-and-hairy/687423/13 "2014-05-01T12:57:27Z")
OK, I believe you will enjoy this: You mean the rugae of the dartos? Cf. Where does your lap go when you stand up? ETA: knowing “philtrum”'s got nothing on rugae, I think. ---
**Author:** ![Peter\_Morris](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/peter_morris/32/359_2.png) [@Peter\_Morris](https://boards.straightdope.com/u/Peter_Morris)\ **Post date:** [May 1, 2014, 1:11pm UTC](https://boards.straightdope.com/t/why-is-the-scrotum-wrinkly-and-hairy/687423/14 "2014-05-01T13:11:42Z")
> [@Manduck](#): > > … and it’s hairy because it has hair on it. Okay, why does it have hair on it? If it needs to be cold for maximum sperm production, and hair retains heat, why is it hairy? Seems counter-productive. ---
**Author:** ![don\_t\_ask](https://avatars.discourse-cdn.com/v4/letter/d/e68b1a/32.png) [@don\_t\_ask](https://boards.straightdope.com/u/don_t_ask)\ **Post date:** [May 1, 2014, 1:18pm UTC](https://boards.straightdope.com/t/why-is-the-scrotum-wrinkly-and-hairy/687423/15 "2014-05-01T13:18:02Z")
If thy wrinkly, hairy scrotum offend thee, pluck it out, and cast it from thee: for it is profitable for thee that one of thy members should perish, and not that thy whole body should be cast into hell. ---
**Author:** ![bob\_2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bob_2/32/3341_2.png) [@bob\_2](https://boards.straightdope.com/u/bob_2)\ **Post date:** [May 1, 2014, 2:07pm UTC](https://boards.straightdope.com/t/why-is-the-scrotum-wrinkly-and-hairy/687423/16 "2014-05-01T14:07:54Z")
> [@Peter\_Morris](#): > > Okay, why does it have hair on it? If it needs to be cold for maximum sperm production, and hair retains heat, why is it hairy? Seems counter-productive. My guess would be ancient genes. Back in the day, we all went around naked, and mostly covered in hair. On both sexes the genital area was important to the continuation of the species and developed extra protection. I think that the male organ was generally much smaller then than now and the hair probably more luxurious. ---
**Author:** ![gnoitall](https://avatars.discourse-cdn.com/v4/letter/g/bb73d2/32.png) [@gnoitall](https://boards.straightdope.com/u/gnoitall)\ **Post date:** [May 1, 2014, 2:08pm UTC](https://boards.straightdope.com/t/why-is-the-scrotum-wrinkly-and-hairy/687423/17 "2014-05-01T14:08:40Z")
> [@VunderBob](#): > > You’re saying, if your hands are cold, you should cover your balls? Well, I’ve told my beloved of 30 years that it’s the best hand-warmer you can find. She seems to agree. 😃 ---
**Author:** ![gnoitall](https://avatars.discourse-cdn.com/v4/letter/g/bb73d2/32.png) [@gnoitall](https://boards.straightdope.com/u/gnoitall)\ **Post date:** [May 1, 2014, 2:12pm UTC](https://boards.straightdope.com/t/why-is-the-scrotum-wrinkly-and-hairy/687423/18 "2014-05-01T14:12:36Z")
> [@Machine\_Elf](#): > > Thermal management. As **sitchensis** suggests, there is an optimal temperature for sperm production. Scrotal skin tenses and relaxes in accordance with temperature. You can see this happening in certain situations: > \ > -Spend ten minutes in cold water, or go for a long walk on a very cold winter day. Or if you’re bold/impatient, apply an ice pack directly to your scrotum. Observe that your scrotum contracts tightly up againts your body. It’s too cold, and it’s trying to minimize surface area in order to restrict heat loss. Ah, [the “shrinkage”](http://en.wikipedia.org/wiki/The_Hamptons_(Seinfeld)#Influence_on_popular_culture). (I’d post the applicable Youtube link but I can’t Youtube here. Google “Seinfeld shrinkage” if you need to. It’s the first two returns at the moment.) ---
**Author:** ![Superhal](https://avatars.discourse-cdn.com/v4/letter/s/b4bc9f/32.png) [@Superhal](https://boards.straightdope.com/u/Superhal)\ **Post date:** [May 1, 2014, 2:16pm UTC](https://boards.straightdope.com/t/why-is-the-scrotum-wrinkly-and-hairy/687423/19 "2014-05-01T14:16:42Z")
Hair doesn’t grow out of my scrotum, it sits on top like a bad toupee. ---
**Author:** ![Artemis\_Tardis](https://avatars.discourse-cdn.com/v4/letter/a/4bbf92/32.png) [@Artemis\_Tardis](https://boards.straightdope.com/u/Artemis_Tardis)\ **Post date:** [May 1, 2014, 2:22pm UTC](https://boards.straightdope.com/t/why-is-the-scrotum-wrinkly-and-hairy/687423/20 "2014-05-01T14:22:23Z")
I tried once to wax my scrotum, and it was the most painful thing I ever did. Is there any other way to trim our bush without excruciating pain or having a blade rubbing against our balls? [Next page](https://boards.straightdope.com/t/why-is-the-scrotum-wrinkly-and-hairy/687423.md?page=2)