# why two nostrils? **URL:** \ **Category:** Factual Questions\ **Created:** [May 16, 2005, 5:00pm UTC](https://boards.straightdope.com/t/why-two-nostrils/304088 "2005-05-16T17:00:28Z")\ **Posts on this page:** 19\ **Page:** 1
**Author:** ![drhess](https://avatars.discourse-cdn.com/v4/letter/d/94ad74/32.png) [@drhess](https://boards.straightdope.com/u/drhess)\ **Post date:** [May 16, 2005, 5:00pm UTC](https://boards.straightdope.com/t/why-two-nostrils/304088/1 "2005-05-16T17:00:28Z")
Why do mamals, birdies, fishies and many other creatures have two nostrils? Do any have three? Does an elephant have one or two? Just wondering… :rolleyes: ---
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [May 16, 2005, 5:45pm UTC](https://boards.straightdope.com/t/why-two-nostrils/304088/2 "2005-05-16T17:45:32Z")
Last time I saw the business end of an elephant’s trunk I saw two nostrils. I assume the elephant must have an 8-foot septum. ---
**Author:** ![ouryL](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ouryl/32/6067_2.png) [@ouryL](https://boards.straightdope.com/u/ouryL)\ **Post date:** [May 16, 2005, 6:34pm UTC](https://boards.straightdope.com/t/why-two-nostrils/304088/3 "2005-05-16T18:34:58Z")
Nature seems to favor bilateral symmetry. ---
**Author:** ![mittu](https://avatars.discourse-cdn.com/v4/letter/m/ecd19e/32.png) [@mittu](https://boards.straightdope.com/u/mittu)\ **Post date:** [May 16, 2005, 7:17pm UTC](https://boards.straightdope.com/t/why-two-nostrils/304088/4 "2005-05-16T19:17:16Z")
> [@ouryL](#): > > Nature seems to favor bilateral symmetry. Wouldn’t you still have bilateral symmetry if you had only one nostril? If you cut a person in half and created a mirror image of one of the halves you would be left with a whole person, with one nostril. ---
**Author:** ![Metacom](https://avatars.discourse-cdn.com/v4/letter/m/ecae2f/32.png) [@Metacom](https://boards.straightdope.com/u/Metacom)\ **Post date:** [May 16, 2005, 7:20pm UTC](https://boards.straightdope.com/t/why-two-nostrils/304088/5 "2005-05-16T19:20:45Z")
> [@ouryL](#): > > Nature seems to favor bilateral symmetry. Then why not two nostrils on each side? 😛 ---
**Author:** ![mittu](https://avatars.discourse-cdn.com/v4/letter/m/ecd19e/32.png) [@mittu](https://boards.straightdope.com/u/mittu)\ **Post date:** [May 16, 2005, 7:32pm UTC](https://boards.straightdope.com/t/why-two-nostrils/304088/6 "2005-05-16T19:32:42Z")
I think [this](http://www.news-medical.net/?id=6056) might provide the answer. > [@](#): > > We land-based vertebrates or “tetrapods” (mammals, birds, reptiles, and amphibians) originally descend from fish, and fish cant breathe through their nose. On the side of a fish’s head there are two nostrils, one front and one back, that form the opening to a little sac containing the olfactory organs: water flows in through the front nostril and out through the back one, but there is no connection whatsoever to the throat. In other words, fish can smell with their nose, but not breathe. It seems it may just be a hangover from the fish we evolved from, who needed to have two nostrils to allow water to flow through rather than causing drag. ---
**Author:** ![silk1976](https://avatars.discourse-cdn.com/v4/letter/s/8edcca/32.png) [@silk1976](https://boards.straightdope.com/u/silk1976)\ **Post date:** [May 16, 2005, 10:00pm UTC](https://boards.straightdope.com/t/why-two-nostrils/304088/7 "2005-05-16T22:00:45Z")
> [@mittu](#): > > I think [this](http://www.news-medical.net/?id=6056) might provide the answer. > > It seems it may just be a hangover from the fish we evolved from, who needed to have two nostrils to allow water to flow through rather than causing drag. Isn’t it odd though that we have two of many things we dont really need to live (arms, legs, eyes, ears, nostrils), yet we have only one heart. ---
**Author:** ![WhyNot](https://avatars.discourse-cdn.com/v4/letter/w/c77e96/32.png) [@WhyNot](https://boards.straightdope.com/u/WhyNot)\ **Post date:** [May 16, 2005, 10:32pm UTC](https://boards.straightdope.com/t/why-two-nostrils/304088/8 "2005-05-16T22:32:58Z")
> [@silk1976](#): > > Isn’t it odd though that we have two of many things we dont really need to live (arms, legs, eyes, ears, nostrils), yet we have only one heart. I always found it odd that our ousides are so bilaterally symetrical, but our innards aren’t. (Except for the bones and the kidneys.) Seems like the outards would be less important than the innards. ---
**Author:** ![Gary\_T](https://avatars.discourse-cdn.com/v4/letter/g/3ec8ea/32.png) [@Gary\_T](https://boards.straightdope.com/u/Gary_T)\ **Post date:** [May 16, 2005, 11:24pm UTC](https://boards.straightdope.com/t/why-two-nostrils/304088/9 "2005-05-16T23:24:58Z")
What’s “important” isn’t a determining factor here. It’s a combination of what works and what an organisms predecessors had. ---
**Author:** ![MLS](https://avatars.discourse-cdn.com/v4/letter/m/919ad9/32.png) [@MLS](https://boards.straightdope.com/u/MLS)\ **Post date:** [May 17, 2005, 12:48am UTC](https://boards.straightdope.com/t/why-two-nostrils/304088/10 "2005-05-17T00:48:21Z")
The digestive innards and their related glands are variations on one long tube from mouth to exit. Most of the other innards – reproductive gizzards, kidneys, lungs – are bilaterally symmetrical. The heart, while it’s not part of a pair, and is not \*exactly \* symmetrical, is a variation on a bilateral form. It’s got a left and a right half, a top and a bottom half, but some parts have developed into larger structures is all. ---
**Author:** ![Reeder](https://avatars.discourse-cdn.com/v4/letter/r/c6cbf5/32.png) [@Reeder](https://boards.straightdope.com/u/Reeder)\ **Post date:** [May 17, 2005, 1:21am UTC](https://boards.straightdope.com/t/why-two-nostrils/304088/11 "2005-05-17T01:21:08Z")
> [@MLS](#): > > snip… > > Most of the other innards – reproductive gizzards, > > Snip… Reproductive gizzards?? You do know what gizzards are used for don’t you? Hint…they ain’t reproductive. ---
**Author:** ![Darwins\_Finch](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darwins_finch/32/20304_2.png) [@Darwins\_Finch](https://boards.straightdope.com/u/Darwins_Finch)\ **Post date:** [May 17, 2005, 1:23am UTC](https://boards.straightdope.com/t/why-two-nostrils/304088/12 "2005-05-17T01:23:40Z")
> [@WhyNot](#): > > I always found it odd that our ousides are so bilaterally symetrical, but our innards aren’t. (Except for the bones and the kidneys.) Seems like the outards would be less important than the innards. [Find it odd no more!](http://boards.straightdope.com/sdmb/showpost.php?p=2582082&postcount=13) Also, note that the heart, while singular, [begins as two endocardial tubes](http://www.meddean.luc.edu/lumen/MedEd/GrossAnatomy/thorax0/heartdev/main_fra.html) (click on the “formation of the heart tube” link from there), which later fuse as development progresses. ---
**Author:** ![MLS](https://avatars.discourse-cdn.com/v4/letter/m/919ad9/32.png) [@MLS](https://boards.straightdope.com/u/MLS)\ **Post date:** [May 17, 2005, 1:35am UTC](https://boards.straightdope.com/t/why-two-nostrils/304088/13 "2005-05-17T01:35:55Z")
> [@Reeder](#): > > Reproductive gizzards?? > > You do know what gizzards are used for don’t you? > > Hint…they ain’t reproductive. I was speaking metaphorically. Gizzards = innards. If we were being technical, gizzards generally = poultry stomachs. ---
**Author:** ![WhyNot](https://avatars.discourse-cdn.com/v4/letter/w/c77e96/32.png) [@WhyNot](https://boards.straightdope.com/u/WhyNot)\ **Post date:** [May 17, 2005, 1:41am UTC](https://boards.straightdope.com/t/why-two-nostrils/304088/14 "2005-05-17T01:41:43Z")
> [@Darwin's Finch](#): > > [Find it odd no more!](http://boards.straightdope.com/sdmb/showpost.php?p=2582082&postcount=13) Very well explained, as usual. Thank you. Do you teach this stuff? ---
**Author:** ![Reeder](https://avatars.discourse-cdn.com/v4/letter/r/c6cbf5/32.png) [@Reeder](https://boards.straightdope.com/u/Reeder)\ **Post date:** [May 17, 2005, 1:43am UTC](https://boards.straightdope.com/t/why-two-nostrils/304088/15 "2005-05-17T01:43:06Z")
> [@MLS](#): > > I was speaking metaphorically. Gizzards = innards. > > If we were being technical, gizzards generally = poultry stomachs. Close The gizzard is the second part of the stomach. Most fowl will eat small stones that situate themselves in the gizzard to grind seed and other hard foods the bird eats. Yep…I’m a country boy. How can you tell? ---
**Author:** ![Good\_Egg](https://avatars.discourse-cdn.com/v4/letter/g/96bed5/32.png) [@Good\_Egg](https://boards.straightdope.com/u/Good_Egg)\ **Post date:** [May 17, 2005, 1:48am UTC](https://boards.straightdope.com/t/why-two-nostrils/304088/16 "2005-05-17T01:48:29Z")
I’d thought it was because we have 2 lungs, and one nostril usually gets stuffed. ---
**Author:** ![Reeder](https://avatars.discourse-cdn.com/v4/letter/r/c6cbf5/32.png) [@Reeder](https://boards.straightdope.com/u/Reeder)\ **Post date:** [May 17, 2005, 1:53am UTC](https://boards.straightdope.com/t/why-two-nostrils/304088/17 "2005-05-17T01:53:52Z")
> [@Good Egg](#): > > I’d thought it was because we have 2 lungs, and one nostril usually gets stuffed. Your nostrils open into your throat. Well before your lungs. I think your onto something about one being stuffed though. ---
**Author:** ![Good\_Egg](https://avatars.discourse-cdn.com/v4/letter/g/96bed5/32.png) [@Good\_Egg](https://boards.straightdope.com/u/Good_Egg)\ **Post date:** [May 17, 2005, 1:55am UTC](https://boards.straightdope.com/t/why-two-nostrils/304088/18 "2005-05-17T01:55:57Z")
:dubious: sniff ---
**Author:** ![Darwins\_Finch](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darwins_finch/32/20304_2.png) [@Darwins\_Finch](https://boards.straightdope.com/u/Darwins_Finch)\ **Post date:** [May 17, 2005, 2:45am UTC](https://boards.straightdope.com/t/why-two-nostrils/304088/19 "2005-05-17T02:45:33Z")
> [@WhyNot](#): > > Very well explained, as usual. Thank you. Do you teach this stuff? Nah. I’m just a hobbiest. But thanks 🙂