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A Unified Theory of Animal Locomotion
Roland Piquepaille writes "You probably already know that there is a master equation for all life processes based on metabolism. Now, physicists from Duke University have applied the so-called 'constructal theory' to explain how running, flying and swimming modes of locomotion are similar even if they're apparently unrelated. This single unifying physics theory explains how fast animals get from one place to another and how rapidly and forcefully they step, flap or paddle in relation to their mass. In other words, these scientists argue that the characteristics of animal shape and locomotion are predictable from physics."
the characteristics of animal shape and locomotion are predictable from physics
They must be using real animals only. I know for a fact that the Pegasus's shape (to cite just one famous example) isn't predictable from physics.
--MarkusQ
Roland Piquepaille and Slashdot
This is question I have asked my daughter from time to thing about... Are Bird and Fish the same or different?
This article starts to show that yes they are.
For me thought the answer is yes they are. They both can move 3 dimentally in they fuild mediums... Air and Water. Just one is just more dense then the other.
Best example of this is Penguin. They "fly" in water.
these scientists argue that the characteristics of animal shape and locomotion are predictable from physics
I wonder who could expected the outcome to be the other way around.
and how rapidly and forcefully they step, flap or paddle in relation to their mass.
Can't we do that already, as in... Oh look, the animal weighs 100 lbs and has two legs on the ground at any given point, so each leg has an average of 25 lbs of force on it?
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Wow, I never would have guessed that you could predict the charactaristics and shape of an animal by the physics. When's the last time you would have guessed a bird was shaped like a cube? Or maybe a fish shaped like a donut? I hardly think it is amazing that you can predict the shape of an animal from it's physics. But hey, maybe these guys don't get out much...
Robotics researchers already knew that something like 'animal' locomotion could be implemented based on the principles of physics. ie. given the right mechanical setup, locomotion is almost automatic and takes no supervision by a computer.
Actually, it's what you'd expect. Animals would naturally evolve to move in an efficient manner. It would give them an evolutionary advantage. What the bleep did these guys expect?
www.sciencenews.org/articles/20050806/bob8.asp
"Can't we do that already, as in... Oh look, the animal weighs 100 lbs and has two legs on the ground at any given point, so each leg has an average of 50 lbs of force on it?"
*Fixed*
Sorry.
http://www.TheGamerNation.com/Forums
It is the same thing, swimming through a liquid, just many orders of magnitude different in viscosity.
I'm pretty sure that my own running speed is within an order of magnitude of almost anything with legs, regardless of its mass. That leaves a lot of biological interest within these simple physical parameters.
Well if they're fast animals, and they're going from one place to another, perhaps they do it by moving quickly? Ever considered that?
In Nature, as in many other things- Form follows function.
Fight psychopharmacological mccarthyism. http://www.norml.org/
I have begun to wonder if perhaps the dumb articles are getting posted just so we can discus the level of dumb out there.
As a nerd though I would much prefer to read people discussing smart.
Don't know something? Look it up. Still don't know? Then ask.
Bejan finally realized the answer. Although fish are neutrally buoyant, they still have to push water out of the way to move forward, he said. So THAT'S what I've been doing wrong! Push water OUT of the way to move forward...thank you Bejan. Thank you. God this article was dumb.
It could be just "bad luck" -- evolution isn't guaranteed to find the best solution to anything, only a solution that is "good enough" to guarantee survival of the species (otherwise the species would have gone extinct). But putting that aside, there are probably structural reasons why animals never evolved wheels -- for example, how would do you connect nerves or blood vessels to an appendage that needs to be able to rotate freely?
Finally, it could be that in nature wheels aren't actually "better" after all. There wouldn't be much use in being able to roll down a freeway at 50MPH if there are no freeways, and your snazzy evolved bio-wheels keep getting stuck in the mud...
I don't care if it's 90,000 hectares. That lake was not my doing.
If such methods are better, why has no animal evolved them?
We have.
...in this article is, "...with a given gravity and density of their tissues, the same basic patterns of their design would evolve again."
This is important because it would suggest that were humans ever to travel to an "Earth-like" planet, we would likely find life-forms that would appear quite familiar to us. We would not likely find "exotic" life-forms that were nothing like what we'd seen before.
Over-the-top Response Guy! Giving "Over-the-Top Responses" since 1970.
I was thinking the exact same thing.
How we know is more important than what we know.
"Or maybe a fish shaped like a donut?"
I hate to break this to you but most animals (including fish and humans) are shaped like donuts (tube surrounded by the organisim). This is not the only "body plan", there are ~30 others still around today, (eg: Jellyfish have only one orifice). All body plans that have ever existed hail back to (or before) the Cambrian explosion
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
How come there aren't three/five/seven limbed critters running around? (star fish don't count)
Is symmetry that important?
I wouldn't claim a monkey's tail or an elephant's nose is a fifth limb, even though they're very functional.
[Fuck Beta]
o0t!
For doing software simulations of walking creatures or robots, I've used the Yobotics Simulation Construction Set. It's reasonably easy to get started, given the complexity of physics simulations. Also, they have a free trial download, so it's great if, like me, you just want to play around.
Your design to a real part online: Big Blue Saw
I don't get it. First, these glorious physicists tell us the laws of physics dictate that a Bumble-Bee can't possibly fly, then they tell us there's an equation that shows us how fast he can go, and how far. (flying, at that.) Somebody let me know what I'm missing here.... I'm not Sherlock Holmes, ya know?
Some bacteria have a neat rotary motor. There's way more flagellated bacteria than humans on the earth, so I wouldn't classify it as "almost entirely missing".
Even better, sperm has a rotary joint. Just think, you could be holding a counterexample to the above post in 5-10 minutes (well, male Slashdotters anyway - female ones might have to drive a bit).
Because God didn't invent them, only godless heathens after they became impure invented them.
Science fiction writers! Yes, SF writers, never again hand me your alien in the form of a flaming flying football, or a man crayola'd green with spikes taped to his ears, or an 80-ton katydid. If you have one of those, it belongs in the *fantasy* section. In science fiction, I should be able to picture the whole chain of evolution for the species, and if it's sentient, I should be able to marvel at it's natural design and be able to appreciate how it must have become the dominant species on it's planet.
I'm curious what his equations would reveal about dinosaur locomotion. I've seen a lot of people claim that dinosaurs could never move under today's Earth gravity, or that pterodactyls could never fly. Wouldn't this guy's equations tell us not only whether or not they could, but how fast they'd likely travel and what they're walking, swimming, and flying capabilities might have been?
E pluribus unum
title says all
..........FULL STOP.
Because ball bearings are a bitch and a half to maintain from organic tissue: there are very few free-spinning joints in nature because making them smooth, round enough to spin, and not attached between the "wheel" and the "axle" to that it can actually spin is amazingly difficult.
A few animals roll effectively for short distances, but it's terribly inefficient because the you have to get the angular thrust from somewhere: if you're going to bother to have legs, why not just walk with them?
Comment removed based on user account deletion
There are certainly plenty of single-celled critters and even some larger parasites that use the screw as a means of locomotion. The wheel is a whole different problem. In order for it to work it has to be totally detached from its axle. That makes minor things like circulation, nerve transfer etc. rather difficult. Topologically, life forms tend to be of order one - donuts with skin on the outside and some form of digestive system on the inside. I think it's safe to say that there are NO known organisms that consist of two wholly independent parts (Master/slave relationships don't count!). /hazard..
No, Will Wright's working on a method to procedurally generate Roland Piquepaille Slashdot submissions.
The theory of relativity doesn't work right in Arkansas.
the wheel and the screw. If such methods are better, why has no animal evolved them?
Because they aren't better: The real world has rocks on it.
You can't take the sky from me...
There are spiders (and snakes?) that ball up and roll down hills/sand dunes.
Other than that, I'd imagine that rotary mechanism's are biologically quite difficult.
However, it's not as 'dumb' as someone mistaking a press release for the actual scholarly scientific article.
I didn't find a link to the article in the press release, and I'm too lazy to bother searching through the journal's Table of Contents to find the authors to get the appropriate link to the article itself, so instead I'll cut and paste the relevent part from the press release.
make world, not war
"If such methods are better, why has no animal evolved them?"
If wheels are "better" why doesn't everyone wear rollerskates instead of shoes?
Wheels and screws are human inventions and therefore are a result of evolution. There seems to be no reason to assume it is even possible to create large scale living wheels from protien.
Rotary motion: Religious fanatics often claim the rotary motion seen in the tails of some micobes is conclusive proof for their drivel.
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
This guy is scum and the fact that Slashdot editors continue to post his stuff says a lot about how they view their readers.
So like hell we'll simmer down, cuz I'm sure that's just what the editors and Roland would want.
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And here we go again: another rule of thumb and back of the envelope calculation that biologists used to perform anyway gets reified and turned into a fundamental theory.
This is, perhaps, is the most universal law of the 21st century: ideas that didn't use to count as sound scientific theories or engineering principles have become acceptable as such.
Speaking of animal motion, I just stumbled upon this antique book for sale from 1882. I remember learning about it a while ago from an animation class I had in art school. It's a fabulous book with loads of early photos and research into the motion of a horse. I believe it's a first edition as well.
Horse in Motion
that would be enough to assist a 5 oz. bird carrying a 1 lb. coconut to Mercia? ;-)
The rotary motion developed for our vehicles can last on its own for about 5 years... if you are constantly putting pure fuel into it, changing the lubrication and performing other maintenance. Then you start replacing parts, then major parts fail and the entire system eventually has to be replaced.
The mechanics and engineering of building something the only needs to run for a few years are quite different from the engineering required to develop units that would self-repair, self-maintain, self-fuel and self-clean. In the wild, they also need to reproduce. None of those features are addressed very well by a motion system that relies on extremely high heat and large, heavy moving parts that need to withstand that type of heat and pressure.
The wheel, drive train, and engine are all at odds with the engineering principles required of living creatures.
"But putting that aside, there are probably structural reasons why animals never evolved wheels -- for example, how would do you connect nerves or blood vessels to an appendage that needs to be able to rotate freely?"
Just have some hard, crusty material become the wheels, like horn or bone or beak material. You could have the animals grow new ones every so often, like the rattles on a rattlesnake.
Computers are useless. They can only give you answers.
-- Pablo Picasso
Perhaps not animal, but the Prokaryotic Flagellum bacteria does have wheels for locomotion as per this article
geek page at KY speaks
It's a matter of finding local maxima. Genetic algorithms commonly used in research will rarely find the global maximum. Also, it's a matter of how useful these actually are in an environment. Snakes use a slithering motion that can be compared to that of a screw, with muscles moving back and forth. This motion is highly efficient and allows them to evade predators quite quickly. But for a large land-based creature, constant rotation would not lend itself towards being a viable form of life; finding and catching prey would be quite difficult. Can you imagine a creature looking something like an enormous screw sliding around on the land? It's not exactly intimidating when you know you can sidestep it or simply stay out of its way. Screws then, just aren't as efficient at doing what legs do.
Famously, Pixar's first film Luxo Jr is based on the same principle. They set up the armature, and then did a global optimisation process to minimise the energy expended for the lamps to hop around.
(BTW, for the would-be pedants present: André & Wally B was not technically a Pixar film, since it was made while everyone was still at Lucasfilm.)
sub f{($f)=@_;print"$f(q{$f});";}f(q{sub f{($f)=@_;print"$f(q{$f});";}f});
So my two ton exoskeleton will let me fly?
Mine does. http://stationair.cessna.com/spec_gen.chtml
"I've got more toys than Teruhisa Kitahara."
So giant ant overlords could only evolve on a planet with less gravity or intense pressures? Or maybe have bouyancy like at the bottom of our oceans. Maybe we should worry about giant lobstermen.
I would like to know how this applies to humans in space. Will I somday be able to fly under my own power in a lunar gymnasium like in an old Heinlein story I once read?
Liberals call everyone Nazis yet they are the closest thing to it.
Rotary motion, almost entirely missing from biology
Tumbleweeds roll their seeds many kilometres to new locations, speargrass seeds have a spiral tail that reacts to moisture to screw the seed head into into the ground, the spherical shape of many seeds is designed to roll them away from the parent plant.
There are plenty of rotary motions if you look for them. Problem is, it's not efficient in most circumstances.
"I've got more toys than Teruhisa Kitahara."
Maybe we should worry about giant lobstermen.
Only the ones trying to practice medicine. They're all quacks.
God invented whiskey so the Irish would not rule the world.
Much like humans "are" bananas, if the statistic I heard of 60% shared DNA is correct...
What is the airspeed velocity of an unladen swallow?
On a similar vein are all fish rear wheel drive?
I know on the land animal front most are, with exceptions such as the elephant (4-wheel drive) and the hyena (I believe has a strange and unique front wheel drive motion).
So giant ant overlords could only evolve on a planet with less gravity or intense pressures?
From what I've heard, the primary factor that keeps insects from growing much larger than they do here on earth, is the oxygen level. From what I remember, this is because the insects "breathe" through their skin, and as the insect increases in size, the interior grows too large to be sustained from the limited surface area.
Here I was re-reading my somewhat battered copy of "On Growth and Form" and this turns up ... sweet.
Bitter and proud of it.
The drag of a streamlined body underwater in deep water does not include a significant term that is a function of gravity.
If you really want to look into it start from the wave resistance equations invented by Michell, rediscovered by Havelock and solved by Castle.
So, does that mean the rest of the article is wrong?
Because there are other relations too that matter.
Locomotion is just one dimension. Most things are optimized compromises that try to achieve many things. Adaptability, fertility, finding food, problem solving to mention few when we talk about life.
If some life forms would be altogether dependant only on locomotion, they would propably develop wheel as their best form of existense or something similar depending on enviroment. Instead 'best' is best compromise when we take account 'what else species need to survive'.
I'm inclined to think that you're good what you have to do, locomotion is important thing but hardly to such extend it would override everything. If we look life in this planet, I'd wager we can't prove that owning fastest or most efficient locomotion would make any species most able to survive. Thus maxium effiency in locomotion isn't needed ever so it doesn't exist.
Or otherwise we would be all gaselles or something much more faster in locomotion than man is. I don't think dinosaurs where awfully effience and fast either were they?
Nobody knows the trouble I've seen, nobody knows has the trouble seen me, even I sometimes wonder why I write these line
I can just see the MythBusters trying to bust or prove the myth that Bumblebees can fly - or likewise come up with a way to make a bumblebee fly.
You have finally proven what God knew all along. Could a random process be self-optimizing? This is yet more proof of His infinite wisdom.
...it's almost as if they were designed that way, by, oh, i dunno, the same creator.
Am I the only one reminded of "the amber spyglass" (http://en.wikipedia.org/wiki/The_Amber_Spyglass) Where wheeled creatures are a crucial part of the story???
"The weirdest thing about a mind, is that every answer that you find, is the basis of a brand new cliche" -
The hoop snake is very good at rolling.
Exam 4/C again. Maybe I'll do better this time.
Be a hedgehog - roll into a ball and voila! Instant rolling!
"The weirdest thing about a mind, is that every answer that you find, is the basis of a brand new cliche" -
I think there are several problems with wheels. The first being that it's far more difficult to traverse rough terrain with wheels than it would be with legs.
There are also significant technical problems. One problem is that there's no real way to deliver power to wheels in a biological organism. Not only that, it would require a complex system which includes a suspension and a method for turning those wheels. The wheels would also have to be a seperate organic mass which has grown out of, but remains attached to the body of the organism. Then there's the problem of friction and wear. An injured animal may still be able to move itself around, but an animal who loses one or more of it's wheels, something which would probably happen easily, would almost certainly die on the spot.
Interestingly enough, while a wheel is a simple concept, legs are a far easier to implement in nature. That's not to say that on some other planet the conditions aren't ideal for animals with wheels.
er.. almost anything that uses cilla for locamotion harnesses rotory motion. http://en.wikipedia.org/wiki/Motor_protein If you have not come across these before then check the out they are facinating. Nature is way ahead of what we have achieved so far
Actually, your arguments about wheels in nature bring me back to an issue I was pondering yesterday. I finally sat down and watched Firefly (all 15 episodes) yesterday, and as is my nature, I started trying to pick apart the show, especially regarding the use of "old technology" interspersed with "new technology". Chiefly, if they can fly between planets, why are they using horses for transportation and not some other sort of conveyance. What you say about wheels not being much use if there are no freeways comes very close to summing up my eventual conclusion on the issue. Without a good, mostly flat surface, wheels really aren't much use. One of the biggest reasons horses were probably so popular with the settlers in the show was due to their ability to handle rough terrain. They can do things that cars can't do, such as step over obstacles and dynamically adjust their footing in order to find the best traction in low tracion situations. Quite simply, wheels are extremely convenient in developed areas, but there probably weren't a whole lot of areas like that until the last couple of thousand of years or so.
(As an aside, the other primary reasons that I can see for using horses on a remote planet have to do with the "maintenance" and "fuel" problems. You can fuel your horses with a much more easily harvested fuel that is also renewable. As for maintenance, well they either maintain themselves, or they get turned into glue. Not to mention, there's the added benefit of having the conveyances themselves design and construct next years model, thereby leaving the entire process up to the true experts.)
If Murphy's Law can go wrong, it will.
As long as nobody grabs their antennae or tries to put one on a plate, we should be safe!
There's another sad tale of modern pollution. I looked it up, and hoop snakes are dying out. It seems that, due to pollution, the hoop snakes are no longer breeding like they once were. Apparently the females now roll counter-clockwise and the males still roll clockwise. This makes breeding difficult, as anyone can see.
I cried real tears when Li Mu Bai died.
That, and the wheel would probably be too big of a jump.
It's one thing to realize that an animal with a backbone, a head, a tail, and four or so limbs can go through a large amount of permutations to give us everything from simple critters, to snakes to dinosaur to platypus -- the basic vertebrate shape is fairly well evidenced in all of em. It doesn't represent a complete departure from a basic shape, but the elements of a fish skeleton are echoed in our own.
It's a whole different ball game to change the existing shapes in any way which ends up at wheel. It's not like by infinitely permuting the components you'd end up there, because it's a complete departure. The wheel as a limb would be almost orthogonal to all of the other limbs which a have evolved. Wheels would almost have to come out of the blue competely.
One thing that's always struck me when you see the shapes that have evolved, is the kernel of similarity which is common among the ones which had common ancestors -- no matter how widely different they ultimately ended up.
While there is huge diversity in what they ended up as, there's an underlying similarity to all of it. The fore-limb and rear-limb arrangement seems to be more of the starting point from which everything else came. Things like gears, wheels and the like don't seem likely to come out of the malleability of those basic structures.
Lost at C:>. Found at C.
The contest for ages has been to rescue liberty from the grasp of executive power. -- Daniel Webster
People like Roland are parasites of the internet, leeching off the efforts of others and preventing them from being compensated for their work.
Your point about why the post was informative is valid, however the rest of your post is nothing but flamebait. You make no case for your argument other than "I'm on crack for having morals and a sense of fairness" and you somehow see this as pathetic.
I'm all for getting great content, and people like Roland are directly opposed to that by the method of which they make their living.
As to your point about quit whining because it won't change anything...well, that is entirely possible. However I can be absolutely certain that it won't change anything if I just keep quiet about it.
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the primary factor that keeps insects from growing much larger than they do here on earth, is the oxygen level
There are other factors, and one was actually discovered back in the Renaissance. That is, muscular strength increases with height squared, but body weight increases with height cubed.
Take a 1 cm ant which can lift 25 times its own weight (as is typical). If it magically grew to 10 cm long, it could only carry itself plus 1.5 other ants. (Compare how little ants carry around leaves bigger than they are, while large dung beetles can barely roll a ball of around their own weight) And if it expands to a full meter long, it could only lift 1/4 of it's weight, making it totally immobile.
...'Cause they're fast!