# Why two testicles? **URL:** \ **Category:** Factual Questions\ **Created:** [March 14, 2003, 6:44am UTC](https://boards.straightdope.com/t/why-two-testicles/161277 "2003-03-14T06:44:42Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![aeropl](https://avatars.discourse-cdn.com/v4/letter/a/f05b48/32.png) [@aeropl](https://boards.straightdope.com/u/aeropl)\ **Post date:** [March 14, 2003, 6:44am UTC](https://boards.straightdope.com/t/why-two-testicles/161277/1 "2003-03-14T06:44:42Z")
I’m missing something here: Why are there two testicles on males? We have two eyes for a reason, we have two ears for a reason, but why two balls? I don’t see any reason why a guy would need two when one does the job just fine. ---
**Author:** ![BobT](https://avatars.discourse-cdn.com/v4/letter/b/8e8cbc/32.png) [@BobT](https://boards.straightdope.com/u/BobT)\ **Post date:** [March 14, 2003, 6:49am UTC](https://boards.straightdope.com/t/why-two-testicles/161277/2 "2003-03-14T06:49:35Z")
Why do women have two ovaries? Why do nearly all people have two kidneys? Or two lungs? ---
**Author:** ![Tuckerfan](https://avatars.discourse-cdn.com/v4/letter/t/eada6e/32.png) [@Tuckerfan](https://boards.straightdope.com/u/Tuckerfan)\ **Post date:** [March 14, 2003, 6:50am UTC](https://boards.straightdope.com/t/why-two-testicles/161277/3 "2003-03-14T06:50:23Z")
Well, redundancy is a nice safety factor to have. ---
**Author:** ![Incubus](https://avatars.discourse-cdn.com/v4/letter/i/c68b51/32.png) [@Incubus](https://boards.straightdope.com/u/Incubus)\ **Post date:** [March 14, 2003, 7:03am UTC](https://boards.straightdope.com/t/why-two-testicles/161277/4 "2003-03-14T07:03:22Z")
Why not _three_ then? And why not have other organs (heart, liver, pancreas) which are equally essential for living be redundant? Isn’t Klingon phsiology like that? ---
**Author:** ![stypticus](https://avatars.discourse-cdn.com/v4/letter/s/f05b48/32.png) [@stypticus](https://boards.straightdope.com/u/stypticus)\ **Post date:** [March 14, 2003, 7:27am UTC](https://boards.straightdope.com/t/why-two-testicles/161277/5 "2003-03-14T07:27:16Z")
I for one think three balls would be a bit uncomfortable. I have enough trouble keeping the pair sitting nicely. I’d think the plumbing changes to have two hearts pumping blood would be fairly complex, which may have something to do with the lack of multiple hearts. And, on the question of pairs, why two legs, two arms? Why not five limbs, or six? ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [March 14, 2003, 8:56am UTC](https://boards.straightdope.com/t/why-two-testicles/161277/6 "2003-03-14T08:56:43Z")
Humans, like most other animals, are bilaterally symmetrical. That was established waaaay back in evolution. That’s just the way it happened for us. ---
**Author:** ![moc.liamtoh\_rorrim](https://avatars.discourse-cdn.com/v4/letter/m/f17d59/32.png) [@moc.liamtoh\_rorrim](https://boards.straightdope.com/u/moc.liamtoh_rorrim)\ **Post date:** [March 14, 2003, 10:27am UTC](https://boards.straightdope.com/t/why-two-testicles/161277/7 "2003-03-14T10:27:48Z")
hehe aeropl says “Im missing something here” and then goes on to ask why two are needed… doesnt anyone see the humor? ---
**Author:** ![coffeecat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/coffeecat/32/3405_2.png) [@coffeecat](https://boards.straightdope.com/u/coffeecat)\ **Post date:** [March 14, 2003, 11:37am UTC](https://boards.straightdope.com/t/why-two-testicles/161277/8 "2003-03-14T11:37:59Z")
As my high-school biology teacher used to say, “Do you want me to answer as myself, or do you want me to answer as God?” It works. Birds only have one functioning ovary, and that works too. ---
**Author:** ![legion](https://avatars.discourse-cdn.com/v4/letter/l/838e76/32.png) [@legion](https://boards.straightdope.com/u/legion)\ **Post date:** [March 14, 2003, 11:38am UTC](https://boards.straightdope.com/t/why-two-testicles/161277/9 "2003-03-14T11:38:01Z")
> [@](#): > > \*Originally posted by aeropl \* > \*\*I’m missing something here: Why are there two testicles on males? We have two eyes for a reason, we have two ears for a reason, but why two balls? I don’t see any reason why a guy would need two when one does the job just fine. \*\* Redundancy? Bi-lateral symmetry? If think a more important question is why are they on the outside and not inside the body? ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [March 14, 2003, 11:53am UTC](https://boards.straightdope.com/t/why-two-testicles/161277/10 "2003-03-14T11:53:19Z")
> [@](#): > > \*Originally posted by legion \* > \*\*If think a more important question is why are they on the outside and not inside the body? \*\* The classic answer to that one is that they operate best at a temperature slightly below the normal body temperature (but not too much below, which is why they get hauled in when it is cold). However, why would it not have been possible to simply make them work best at normal body temperature, like the ovaries? Evolution doesn’t always end up producing the most elegant solution to the problem; it has to work largely by modifying stuff that already exists; I’m struggling to explain this adequately, but imagine a fork in the road; if you turn right, you take the road to the coast, if you turn left, you end up in the mountains - after having turned toward the mountains, it may not be possible to simply branch off again and end up at the coast (especially when you have no particular destination in mind) ; you’re stuck with the legacy of a previous bifurcation. ---
**Author:** ![Janie\_Jones](https://avatars.discourse-cdn.com/v4/letter/j/13edae/32.png) [@Janie\_Jones](https://boards.straightdope.com/u/Janie_Jones)\ **Post date:** [March 14, 2003, 4:11pm UTC](https://boards.straightdope.com/t/why-two-testicles/161277/11 "2003-03-14T16:11:52Z")
> [@](#): > > _Mangetout cut to the chase with:_ > **you’re stuck with the legacy of a previous bifurcation.** That’s a very eloquent way of putting it, **Mangetout**. Kudos. (And I’m a gonna steal that phrase and use it as my own! :D) ---
**Author:** ![YiBaiYuan](https://avatars.discourse-cdn.com/v4/letter/y/f475e1/32.png) [@YiBaiYuan](https://boards.straightdope.com/u/YiBaiYuan)\ **Post date:** [March 14, 2003, 4:26pm UTC](https://boards.straightdope.com/t/why-two-testicles/161277/12 "2003-03-14T16:26:12Z")
aeropl, Since you already have several serious answers to your question, would you mind if I made a light-hearted one? The right one is for the boy sperms (Y), and the left one is for the girl sperms (X). 🙂 ---
**Author:** ![Arken](https://avatars.discourse-cdn.com/v4/letter/a/dfb087/32.png) [@Arken](https://boards.straightdope.com/u/Arken)\ **Post date:** [March 14, 2003, 4:35pm UTC](https://boards.straightdope.com/t/why-two-testicles/161277/13 "2003-03-14T16:35:05Z")
Unless you want to give the ‘because God said so’ answer, the reason why anything is the way it is in terms of biology is pretty simple- the ones who didn’t do it that way didn’t survive. ---
**Author:** ![Amp](https://avatars.discourse-cdn.com/v4/letter/a/6a8cbe/32.png) [@Amp](https://boards.straightdope.com/u/Amp)\ **Post date:** [March 14, 2003, 4:45pm UTC](https://boards.straightdope.com/t/why-two-testicles/161277/14 "2003-03-14T16:45:56Z")
One is regular milk and the other is chocolate milk, no wait, I think I screwed that up… ---
**Author:** ![Davebear](https://avatars.discourse-cdn.com/v4/letter/d/bcef8e/32.png) [@Davebear](https://boards.straightdope.com/u/Davebear)\ **Post date:** [March 14, 2003, 5:36pm UTC](https://boards.straightdope.com/t/why-two-testicles/161277/15 "2003-03-14T17:36:06Z")
'Cuz “One is the loneliest number…”. 🙂 ---
**Author:** ![lieu](https://avatars.discourse-cdn.com/v4/letter/l/c2a13f/32.png) [@lieu](https://boards.straightdope.com/u/lieu)\ **Post date:** [March 14, 2003, 5:55pm UTC](https://boards.straightdope.com/t/why-two-testicles/161277/16 "2003-03-14T17:55:32Z")
If I had three I could finally teach myself how to juggle. ---
**Author:** ![Guinastasia](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/guinastasia/32/5751_2.png) [@Guinastasia](https://boards.straightdope.com/u/Guinastasia)\ **Post date:** [March 14, 2003, 8:30pm UTC](https://boards.straightdope.com/t/why-two-testicles/161277/17 "2003-03-14T20:30:18Z")
> [@](#): > > \*Originally posted by Amp \* > \*\*One is regular milk and the other is chocolate milk, no wait, I think I screwed that up… \*\* LOL…my cousin really believed that was true when my aunt was breastfeeding his little brother. ---
**Author:** ![Eutychus](https://avatars.discourse-cdn.com/v4/letter/e/a3d4f5/32.png) [@Eutychus](https://boards.straightdope.com/u/Eutychus)\ **Post date:** [March 14, 2003, 8:47pm UTC](https://boards.straightdope.com/t/why-two-testicles/161277/18 "2003-03-14T20:47:55Z")
Three is too many. One’s not enough. ---
**Author:** ![aeropl](https://avatars.discourse-cdn.com/v4/letter/a/f05b48/32.png) [@aeropl](https://boards.straightdope.com/u/aeropl)\ **Post date:** [March 14, 2003, 10:38pm UTC](https://boards.straightdope.com/t/why-two-testicles/161277/19 "2003-03-14T22:38:45Z")
**YiBaiYuan** : Sadly, some people actually believe that. **Amp, davebear, and lieu** : I laughed out loud. Okay I realize there’s the redundancy issue, but it still doesn’t make sense to me… It’s not like evolution planned to have two in case one testicle got cancer and had to be surgically removed. I don’t see how two could evolve (except for being the result of bilateral symmetry) through natural selection. If you get hit down there, chances are it will destroy both right? How often does one fail and the other keeps working? I guess evolution has a lot of unexplainable things. Okay, I’ll hijack my own thread with a few more questions. 1. Does the human body have three of a kind of any organ for redundancy? 2. What are the theories on why/how bilateral symmetry evolved? ---
**Author:** ![Bearflag70](https://avatars.discourse-cdn.com/v4/letter/b/8e7dd6/32.png) [@Bearflag70](https://boards.straightdope.com/u/Bearflag70)\ **Post date:** [March 14, 2003, 10:50pm UTC](https://boards.straightdope.com/t/why-two-testicles/161277/20 "2003-03-14T22:50:54Z")
I don’t understand the bilateral symmetry thing… why not just one ball right in the center? Why not two penises? Now we’re talkin’ fun! [Next page](https://boards.straightdope.com/t/why-two-testicles/161277.md?page=2)