Unified physics theory explains animals' running, flying and swimming

[Celebration]

http://www.physorg.com/news9459.html

A single unifying physics theory can essentially describe how animals of every ilk, from flying insects to fish, get around, researchers at Duke University's Pratt School of Engineering and Pennsylvania State University have found. The team reports that all animals bear the same stamp of physics in their design.

The researchers show that so-called "constructal theory" can explain basic characteristics of locomotion for every creature -- how fast they get from one place to another and how rapidly and forcefully they step, flap or paddle in relation to their mass. Constructal theory is a powerful analytical approach to describing movement, or flows, in nature.

They said their findings have important implications for understanding factors that guide evolution by suggesting that many important functional characteristics of animal shape and locomotion are predictable from physics.

The findings, published in the January 2006 issue of "The Journal of Experimental Biology," challenge the notion that fundamental differences between apparently unrelated forms of locomotion exist. The findings also offer an explanation for remarkable universal similarities in animal design that had long puzzled scientists, the researchers said.

[skids]

1. What I want to know...

...Is why no animal ever evolved a fully rotatable wheel for any purpose... :-)

(At least that I know of.)

[The Velveteen Ocelot]

2. Ohmygod, the horror, the horror!

A cat with wheels...!

[zbdent]

3. blood circulation

How would it keep attached? And, if it was, how would lubricating it work?

[skids]

5. For something as versatile as DNA...

...I don't think getting liquid into/out of a wheel would be that much of a challenge. I mean we've done it, and we're pretty ham-fisted.

But I'm not necessarily talking about an external wheel -- could be internal -- a gyroscope or turbine.

[Orrex]

10. It's not about what evolution *can* yield in theory

It's about yielding the most efficient response to the demands of the environment. Since, historically, there have been few paved roads, the evolution of a wheeled system of locomotion is less efficient than limb-based motion.

You asked about the absence of internal wheels, and the answer is basically the same—efficient response to the demands of the environment did not yield an internal wheel, especially since other structures (inner ear vs. gyroscope) have existed for a long time anyway.

Of course, Cecil addressed this very question years ago.

[bemildred]

7. Rotifers.

I believe that cilia also rotate.
Still, the absence in larger critters is noticeable.

One could speculate that wheels are not versatile enough, in terms of terrain, to make up for the added efficiency.

[TechBear_Seattle]

8. Not a wheel

A wheel, by definition, requires a free moving disk on an axis. What rotifers have is a disk of cilia around their "mouth." The cilia wave in an oval pattern to sweep food in to the orifice; collectively, this movement of all the cilia looks like a wheel. But it's not :shrug:

A true wheel would require two entirely separate things. One example can be found in The Amber Spyglass by Philip Pullman (book three of the His Dark Materials trilogy), where a sentient race has evolved a symbiotic relationship using giant seedpods for wheels. But it is extremely unlikely that a single, wholistic entity could ever develop a true wheel.

[htuttle]

9. Okay, how about humans?

In one very real sense, the machines humans build to get from place to place are no different than the shell a snail or turtles builds. It's all non-organic matter formed into useful shapes by organic beings. Just because we use our hands to generate our 'exoskeletons' instead of pores in our skin should make little difference. Making things with our hands (and our wonderous opposable thumbs) is a natural as snails building a shell.

So there -- humans 'evolved' wheels for locomotion. :)

[Orrex]

11. Despite your smiley icon, your answer is exactly correct, IMO!

Perhaps our last, lingering, cultural prejudice is our tendency to exclude humans from the "natural" world, as if we're somehow outside or above it. We are natural creatures, and everything we have ever done or will ever do is "natural," whether it's farting or fornicating or inventing nylon. I don't mean it in any touchy-feely "we're one with nature" sort of way, either, because such a philosophy is, in essence, redundant.

We've all heard of religious sects that reject modern medicine as "unnatural" and therefore "against God," but they still wear eyeglasses and comb their hair, as if these are any more "natural" than surgery.

That's one of the reasons why it's so clearly ridiculous when people decry homosexuality or anything else as "unnatural." If we as a species are outside the "natural" world, then everything we do is "unnatural," and that latter term therefore can't credibly have a negative connotation. Alternatively, if we are part of the natural world, then everything we do is natural, and the term "unnatural" becomes a non sequitur.

At most, we can apply the terms "artificial" or maybe "human-made" to things that we imagine to be separate from nature, but even those terms are illusory.

So you are correct in arguing that the the wheel is a product of evolution.

Anyone in disagreement is encouraged to share an example of something that they think is actually unnatural.

[BeFree]

15. Yep, you nailed it

We are not separate from nature, except if we try, unnaturally, to separate ourselves. And, boy, do we try.

There is noahscape. We are, as far as I can tell, the most versatile and adaptable and communicative creatures that ever came naturally to this earth.

None ever needed a wheel before we so desired. None ever desired a wheel before, so there were no wheels. Now, there are wheels.

If we disappeared today, methinks dogs would desire to make wheels, eh? Do they not show a desire to travel upon our wheels? Wouldn't they create wheels someday?

[htuttle]

16. Dogs would re-invent the automobile

...just to hang their heads out the windows.

But they'd still have trouble with door knobs....except for my dog, who figured out how to open the fridge a few weeks ago. WHAT A NIGHTMARE! We now have to keep a cinder block in front of the refrigerator door to prevent her from eating all of our food at night. Can you imagine the chaos if she could transmit that knowledge easily to other dogs?

[Celebration]

17. maybe transmitted from a dalmation

That we temporarily had before we found him another home. He learned how to open inside doors that were latched closed. He figured out how to jump and land his paw on the side of the doorknob that would open the door. This was the same dog that when we put him outside and he wanted to be inside, simply jumped through the glass in the window. He wreaked havoc on everything in that room but managed not to hurt himself. This is all probably explained by some physics principle. :)

[htuttle]

4. Wrong!

Columns of slime mold roll like a wheel to move from place to place.

Okay -- it's more of a 'rolling pin' than a proper 'wheel', but it rolls in any case.

on edit:

Whoops! I meant this to be a reply to the post about organic wheels...

[skids]

6. Yeah, rolling the entire body doesn't count. n/t

[Orrex]

12. I'd have to agree

I mean, I can roll laterally down a hill, but that doesn't make me a wheel.


Hmm. Or does it?

[skids]

13. Well, it isn't a totally off base thing to point out...

...I could see it being more likely that an animal that spends a good amount of it's time rolling would be more likely to evolve a wheel to keep some organ upright than it would for the converse to happen.

[oneighty]

14. Well the famous 'Hoop Snake'

is,hmmm I guess I better not go there

180

[Odin2005]

18. The bacterial flagellum is similar to a steam turbine

the base of the "whip" spins in a cylidrical "cuff" in the cell membrane. The "whip" is spun by the flow of ions through the "cuff".