Why Flamingos Are More Stable on One Leg Than Two | Hacker News Reader

Why Flamingos Are More Stable on One Leg Than Two

theatlantic.com

108 pointsSujan31 comments

Another great example of evolutionary wonders in birds is the albatross. They have a tendon sheath that allows them to lock their wings open. This, combined with their giant wingspan, their relative heft (albatrosses are porkers), and some mysterious sensory mechanism and they are able to take advantage of wind gradients to perform a maneuver called "dynamic soaring", wherein the bird extracts energy from the wind. Scientists have measured the heartrate of soaring albatrosses, and found it to be not much higher than their resting heart rate. Albatrosses use this advantage to journey thousands of miles across the pacific, without landing once.

Some more info:

https://en.wikipedia.org/wiki/Albatross#Morphology_and_fligh...

> wherein the bird extracts energy from the wind.

Just to be clear for others: the bird is gaining kinetic energy and/or elevation (potential energy). It's not extracting energy from the wind and converting it to chemical energy (fat/sugar).

Right, it still has to eat along the way :)

That was a lot of explanation about how the joints lock into place, but that's not what's interesting to me. If I took a steel rod and put a stuffed animal at the top of it, I wouldn't expect it to be inherently stable.

Well, as the article lays out, it's a little more complicated than the leg joints just locking into place. They couldn't figure out how the leg was locking. It's only when they engaged the lock (by picking up the bird by the shin) that they realized the entire body reconfigures to achieve the needed stability:

> When a flamingo shifts onto one leg, two things happen. First, the leg inclines so that the foot moves from being directly under the hip to being directly under the center of the body. Second, the center of mass moves to just in front of the flamingo’s (hidden) knee, so its body weight naturally pulls the hip and knee forward. These two changes, combined with gravity’s pull and the shape of the leg bones, keeps all the joints in place.

The reason anything with two legs is more stable on one foot is that it has the choice to immediately put the free foot anywhere in order to bring about stability.

I have taught this to hikers who were struggling to get over some obstacles such as boulders. Quit standing on both feet and teetering. Always keep one in the air. When you step onto the next rock, lift the recovering foot, and keep it up until you decide the next step.

You said yourself that putting the second foot down doesn't increase stability. It's a paradox.

To answer this from the taijiquan perspective, the stability comes from being properly balanced on one leg. The second leg is a spare for when something happens unexpectedly like a gust of wind. By forcing people to keep one leg off the ground, you're forcing them to balance on one leg and learn to be more stable like that.

If you have no balance, it doesn't work. That's why tai chi is often recommended for older people to improve their balance and reduce the risk of falls.

It's always interesting to see a technique evolve independently in multiple domains.

I practise taijiquan (tai chi) which is very heavily predicated on this principle. A huge part of it boils down to practising being stable on one leg so the other leg can move anywhere. You might be interested in the taiji stepping techniques, but these are not (visibly) part of the forms people generally think of as tai chi, and not all schools bother to teach them.

Of course, it's not the same thing TFA talks about. Especially in the context of traditional Chinese martial arts, with all their associated mythology, I think it's helpful to remember that human physiology is pretty unique, especially when it comes to balance. We're inherently unstable, so becoming more stable takes practise and conditioning. We're not flamingos (or snakes, or white cranes).

A much better write up of this, from one of the people who actually worked on it, was posted the other day: https://theconversation.com/neuromechanics-of-flamingos-amaz...

And the HN discussion: https://news.ycombinator.com/item?id=14408786

The Atlantic story linked here dumbs it down quite a bit.

Heh... Interesting article.

I have a standing desk, and oddly enough, find it much easier to stand on 1 leg than 2. If it didn't take effort to keep my second leg up (in the yoga pose) I could see standing like that for hours. My knee joint locks, and I keep my balance easily with the support of the desk. For some reason, standing on 2 feet is far less comfortable and requires more 'effort'.

Woah I never noticed this but yea, when I am at my standing desk I shift from standing on one leg to standing on the other leg, shifting when my foot complains.

(to address your yoga pose, just sort of half wrap the ankle around the back, doesn't require much/any effort for the second leg if you let the toe drag all the way down towards the ground)

Interesting, I'll give that a try. Thanks!

I assume that's less about your legs being flamingo-like, and more about the way our hips work. You almost never stand around putting equal weight on both legs, when you stand you usually favour one or the other leg, with your body leaning over ever so slightly to balance the weight over that leg.

What work(s/ed?) for me (but only when you have no shoes on) is putting your feet on your knee.

With your left leg raised: put the left heel, on the left-top side of your knee, arch the foot around the knee, so your toes end up on the right side of knee below it.

Works best if you have clothing that has some friction.

As silly as it sounds, this is how I used to wash dishes as a kid. My siblings would say I was being a flamingo.

This article reminded me of a hiking skill I never mastered - the Rocky Mountain Rest Step (the name I learned it by, but I have heard others). It's pretty simple - when hiking on steep slopes, especially with weight (a heavy pack), you train yourself to lock your knee when stepping up to conserve energy and "rest". I always found it rather uncomfortable, but I have climbed with many strong mountaineers who swear by it.

http://rockymountainhikingtrails.blogspot.com/2012/09/learni...

> "We really wanted to do an experiment where we just walked over and gave them a little prod," says Chang. "But the zoo wouldn’t let us."

This is _hilarious_.

Though I doubt that the flamingo would let you come near it, but it could have been a nice alternative to cow tipping:

https://en.wikipedia.org/wiki/Cow_tipping

Also dead fish can swim upstream... evolution has a way of just making things work well mechanically.

I don't think 's true. What fish would that be?

It seems to be possible: http://www.people.fas.harvard.edu/~glauder/reprints_unzipped...

It looks like it sort of is (trout): https://www.youtube.com/watch?v=aRWgqDi-ihs

Here's another example: https://vimeo.com/44887922

http://www.people.fas.harvard.edu/~glauder/reprints_unzipped...

https://www.youtube.com/watch?v=GtuHgl35TT4

And sailboats can sail upwind.

TL;DR (quoted from the article):

"When a flamingo shifts onto one leg, two things happen. First, the leg inclines so that the foot moves from being directly under the hip to being directly under the center of the body. Second, the center of mass moves to just in front of the flamingo’s (hidden) knee, so its body weight naturally pulls the hip and knee forward. These two changes, combined with gravity’s pull and the shape of the leg bones, keeps all the joints in place."

flamingos are cool

and smelly

but cool

Nature smells so bad.

I grew up in Alaska and oh God seals and whales smell so bad.

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