# Are flamingos the only birds with knees that bend backwards? **URL:** \ **Category:** Factual Questions\ **Created:** [April 24, 2021, 12:19am UTC](https://boards.straightdope.com/t/are-flamingos-the-only-birds-with-knees-that-bend-backwards/940653 "2021-04-24T00:19:15Z")\ **Posts on this page:** 16\ **Page:** 1
**Author:** ![Northern\_Piper](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/northern_piper/32/5304_2.png) [@Northern\_Piper](https://boards.straightdope.com/u/Northern_Piper)\ **Post date:** [April 24, 2021, 12:19am UTC](https://boards.straightdope.com/t/are-flamingos-the-only-birds-with-knees-that-bend-backwards/940653/1 "2021-04-24T00:19:15Z")
As in the thread title: are there any other birds with backwards bending knees? ---
**Author:** ![lobotomyboy63](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lobotomyboy63/32/2900_2.png) [@lobotomyboy63](https://boards.straightdope.com/u/lobotomyboy63)\ **Post date:** [April 24, 2021, 12:26am UTC](https://boards.straightdope.com/t/are-flamingos-the-only-birds-with-knees-that-bend-backwards/940653/2 "2021-04-24T00:26:11Z")
I was thinking herons did. Look at an image…seems right. But a quick google brought up a WaPo article. > **[Fun facts about blue herons](https://www.washingtonpost.com/lifestyle/kidspost/fun-facts-about-blue-herons/2011/06/16/gIQAc1bzYJ_story.html)** > > Blue herons are actually more gray than blue. They hunt alone but live in noisy colonies. > ● As with all birds, a heron’s “backward knees” are actually like our ankles. Birds walk on their toes, just like dogs and cats. (Toe walkers are called digitigrades) Their knees are up under their feathers and bend the same way ours do. ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [April 24, 2021, 12:51am UTC](https://boards.straightdope.com/t/are-flamingos-the-only-birds-with-knees-that-bend-backwards/940653/3 "2021-04-24T00:51:15Z")
> [@lobotomyboy63](#): > > Their knees are up under their feathers and bend the same way ours do. Where are their hips? ---
**Author:** ![lobotomyboy63](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lobotomyboy63/32/2900_2.png) [@lobotomyboy63](https://boards.straightdope.com/u/lobotomyboy63)\ **Post date:** [April 24, 2021, 12:56am UTC](https://boards.straightdope.com/t/are-flamingos-the-only-birds-with-knees-that-bend-backwards/940653/4 "2021-04-24T00:56:06Z")
> [@carnivorousplant](#): > > Where are their hips? Further googling… > A flamingo’s hip and knee sit high up inside its body. What bends in the middle of the long flamingo leg is not a knee, but an ankle. (That explains why, to human eyes, a flamingo’s leg looks like it bends the wrong way.) [https://www.sciencenewsforstudents.org/article/how-flamingo-balances-one-leg#:~:text=A%20flamingo’s%20hip%20and%20knee,a%20knee%2C%20but%20an%20ankle](https://www.sciencenewsforstudents.org/article/how-flamingo-balances-one-leg#:~:text=A%20flamingo's%20hip%20and%20knee,a%20knee%2C%20but%20an%20ankle). ---
**Author:** ![romansperson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/romansperson/32/17100_2.png) [@romansperson](https://boards.straightdope.com/u/romansperson)\ **Post date:** [April 24, 2021, 12:56am UTC](https://boards.straightdope.com/t/are-flamingos-the-only-birds-with-knees-that-bend-backwards/940653/5 "2021-04-24T00:56:41Z")
It would appear that their ‘hips’ are right up near their spines. [![](https://upload.wikimedia.org/wikipedia/commons/c/cd/Greater_Flamingo_%28Phoenicopterus_roseus%29_skeleton_at_the_Royal_Veterinary_College_anatomy_museum.JPG) ](https://upload.wikimedia.org/wikipedia/commons/c/cd/Greater_Flamingo_%28Phoenicopterus_roseus%29_skeleton_at_the_Royal_Veterinary_College_anatomy_museum.JPG) ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [April 24, 2021, 1:38am UTC](https://boards.straightdope.com/t/are-flamingos-the-only-birds-with-knees-that-bend-backwards/940653/6 "2021-04-24T01:38:53Z")
I have always avoided chicken thighs, and gone for breasts or tenders. ---
**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:** [April 24, 2021, 1:25pm UTC](https://boards.straightdope.com/t/are-flamingos-the-only-birds-with-knees-that-bend-backwards/940653/7 "2021-04-24T13:25:12Z")
As others have said, what appears to be a knee is actually equivalent to an ankle. The part that sticks out in back is the heel. Nothing is backwards. (And chicken thighs are the best part.) ---
**Author:** ![Northern\_Piper](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/northern_piper/32/5304_2.png) [@Northern\_Piper](https://boards.straightdope.com/u/Northern_Piper)\ **Post date:** [April 24, 2021, 1:43pm UTC](https://boards.straightdope.com/t/are-flamingos-the-only-birds-with-knees-that-bend-backwards/940653/8 "2021-04-24T13:43:13Z")
Fascinating. Thanks all. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [April 24, 2021, 4:15pm UTC](https://boards.straightdope.com/t/are-flamingos-the-only-birds-with-knees-that-bend-backwards/940653/9 "2021-04-24T16:15:18Z")
Said another way, most birds have the backwards-looking feet/legs. Because, like the flamingo, their upper leg bone / femur-equivalent is relatively short and mostly tucked up against the body. And their lower leg bone / tibia-equivalent is a little / a lot longer and more exposed. The thing that makes flamingos really stand out, besides just that they are very long-legged for their body size, is that the upper foot bone and the lower leg bone are very close to the same length. And therefor look similar to human legs whose upper & lower bones are also about the same length. ---
**Author:** ![Terminus\_Est](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/terminus_est/32/3087_2.png) [@Terminus\_Est](https://boards.straightdope.com/u/Terminus_Est)\ **Post date:** [April 25, 2021, 12:15am UTC](https://boards.straightdope.com/t/are-flamingos-the-only-birds-with-knees-that-bend-backwards/940653/10 "2021-04-25T00:15:06Z")
> [@romansperson](#): > > It would appear that their ‘hips’ are right up near their spines Unless you are working with a different definition of “hip”, all birds have hips right up near their spines. Humans have hips right up near their spines. All animals that have hips have them right up near their spines. ---
**Author:** ![mikecurtis](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mikecurtis/32/3284_2.png) [@mikecurtis](https://boards.straightdope.com/u/mikecurtis)\ **Post date:** [April 25, 2021, 12:29am UTC](https://boards.straightdope.com/t/are-flamingos-the-only-birds-with-knees-that-bend-backwards/940653/11 "2021-04-25T00:29:21Z")
Now that that’s answered… If most (all?) animals have knees that bend one way, why do so many robots have knees that bend the other way? ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [April 25, 2021, 12:50am UTC](https://boards.straightdope.com/t/are-flamingos-the-only-birds-with-knees-that-bend-backwards/940653/12 "2021-04-25T00:50:32Z")
Now _that_ is a great question. One I have no clue about. ---
**Author:** ![Senegoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senegoid/32/6606_2.png) [@Senegoid](https://boards.straightdope.com/u/Senegoid)\ **Post date:** [April 25, 2021, 4:34am UTC](https://boards.straightdope.com/t/are-flamingos-the-only-birds-with-knees-that-bend-backwards/940653/13 "2021-04-25T04:34:49Z")
> [@mikecurtis](#): > > If most (all?) animals have knees that bend one way, why do so many robots have knees that bend the other way? They’re not really “humanoid”, despite superficial appearances. They’re flamingoid. Someone discovered it really works better that way. ---
**Author:** ![eschereal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eschereal/32/18939_2.png) [@eschereal](https://boards.straightdope.com/u/eschereal)\ **Post date:** [April 25, 2021, 5:06am UTC](https://boards.straightdope.com/t/are-flamingos-the-only-birds-with-knees-that-bend-backwards/940653/14 "2021-04-25T05:06:33Z")
There must be some proto-animal from which we all developed, because we all have the same form, just with different proportioning. Bats, for instance, have webbed fingers. ---
**Author:** ![mikecurtis](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mikecurtis/32/3284_2.png) [@mikecurtis](https://boards.straightdope.com/u/mikecurtis)\ **Post date:** [April 25, 2021, 6:54am UTC](https://boards.straightdope.com/t/are-flamingos-the-only-birds-with-knees-that-bend-backwards/940653/15 "2021-04-25T06:54:35Z")
> [@Senegoid](#): > > Someone discovered it really works better that way. yes. so why did mother nature decide otherwise/ ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [April 25, 2021, 2:19pm UTC](https://boards.straightdope.com/t/are-flamingos-the-only-birds-with-knees-that-bend-backwards/940653/16 "2021-04-25T14:19:16Z")
> [@Senegoid](#): > > They’re not really “humanoid”, despite superficial appearances. They’re flamingoid. Someone discovered it really works better that way. Is that to say the robots knees are backwards vs humans, or that what looks like the knee on a robot is really the ankle of a much elongated foot? Clearly the greatly elongated foot/ankle is great for running speed; most quadrupeds are built that way, and definitely the fast ones. We also see similar things in the modern high performance prostheses for folks missing legs. Example vid chosen more or less at random: [![](https://img.youtube.com/vi/CNhn711-rLM/maxresdefault.jpg "Are Running Blades Cheating? The Biomechanics of Running Prosthetics | Corporis") ](https://www.youtube.com/watch?v=CNhn711-rLM) I can see advantages on quadruped robots to have the front knees flex forwards and the rear legs flex rearwards. That keeps the legs from colliding. Animals solve that issue with smaller and narrower shoulders than hips so the front legs fit between the rear legs at the gallop. For a robot that just makes teh whole thing a little tippier & less sure-footed. Easier to reverse the rear knees and be done with it. > [@mikecurtis](#): > > … > so why did mother nature decide otherwise/ Luck. It was a 50/50 proposition at some point in pre-history and that critter flipped tails, not heads.