Why has no animal species ever evolved wheels? - by Marie Hansen, Saint Augustine

Cecil's Columns/Staff Reports
1

Hi, this is just my addition to the question that Cecil Adams. answered.

Marie, think for a minute … How would the wheels work ?
In all cases, they must complete a 360 degree rotation and that would mean that the animals either used blood as lubricant to a wet joint to spin it, or if it were fur, it wouldn’t work at all.

All indication to an animal with wheels wouldn’t work because the wheel at SOME point has to be free-flowing which means SEPARATE from the animal itself.

Kind of like a parasite I guess … Then it might work.

That’s all. :slight_smile:

David

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Here’s the link you no doubt meant to include.

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Hi Baldwin:

  • Thanks !
    I’m still learning proper etiquette around here ! :slight_smile:

David

4

Ok I have a corresponding question which I also wish had been answered:

Are there any creatures which have evolved the tripod?

I mean, all creatures seem to have even legs, 2, 4, 6, 8. But a tripod seems inherently more sound than two legs.

I read this in a book once, and ever since then it’s been preying on my mind.

5

  1. An even number of legs goes with bilateral symmetry, and bilateral symmetry goes with having a brain. (No bilateral symmetry, no anterior end. No anterior end, no anterior sensory nexus. No anterior sensory nexus, no brain.)

  2. Tripods are no good for walking unless you’ve got a brain adequate to the job of standing on one leg, in which case it’s far more profitable for a four-legged creature to adopt an upright stance (and gain two arms) than to discard one leg and gain nothing.

  3. Tripods have no advantage over tetrapods for standing still, either, unless the entire system is rigid.

In short, about the only animal that might reasonably have three legs is a giant, lakeshore-dwelling, air-breathing land clam.

6

For odd numbered locomotion you might consider the kangaroo. When walking slowly it brings its tail into use as a fifth limb, when standing it leans back on the tail as third leg, and when fighting it can even briefly balance on its tail alone. Not really a leg, but then a panda’s thumb is not really a thumb. :wink:

7

Maybe blood isn’t the only possible lubricant. The hammer of a piano hinges upon a metal pin where the lubricant is a thin layer of felt. Yes, felt. (I knew you always wondered why you didn’t have to oil a piano.)

Doesn’t make wheels more likely, of course.

8

I was gonna bring up the fabled hoop snake BUT when I went to the link, I see Unca Cece has already been there. Thanks U/C…he takes all the fun out of stuff sometimes. Can’t even spin a good yarn 'round here anymore. :wink:

I still hear it being told as truth occasionally.

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THERE IS NO SUCH THING AS A HOOP SNAKE?!

My entire life has been a lie.

10

I don’t know why, but that had me in gigglefits.

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It got me thinking about these guys.

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While no creature may have evolved a tripod per se, many essentially take advantage of tripods during locomotion. Take a tetrapod and lift one leg, and you’ve got a tripod. Since locomotion generally requires that you do, in fact, lift at least one leg at some point, the remaining three legs act as a tripod lending stability. This is especially true for slow, ponderous animals like turtles, who don’t move their limbs quickly enough to “catch” themselves, should they begin to falter. See here for an illustration of this idea.

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There’s a desert spider that escapes predators by forming its entire body into a wheel and rolling down the dune. I saw it on one of those nature documentaries. It was quite a sight.

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There are quite a few radialy symetrical animals that have 5 or more legs. Starfish for instance.

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And there you are, the starfish being the classic example of a higher animal with no brain.

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M.C. Escher did a couple of wonderful prints on this very idea. The first was Curl-Up, which simply shows a vaguely caterpillarlike creature–presumably some sort of arthropod–that had three sets of humanlike feet. This imaginary creature is capable of great speed by rolling itself into a wheel, and then pushing itself along with its outstretched feet. In this case, however, the creature doesn’t have wheels, but simply becomes one large wheel.

The idea was expanded on in House of Stairs, which demonstrates how the creatures can use their “normal” legs to march up and down stairs, but transform into wheels just before speeding out of the picture. The reverse transformation is seen as other Curl-Ups rush into the picture and prepare to take the stairs.

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Dear Group Mind,

This whole “Why don’t animals evolve with wheels” debate has been kicked around long enough (thirty years, since I remember seeing it appear on my brother’s biology homework when I was just a tot), without what I consider to be a prime factor being taken into consideration.

Animals only evolve a characteristic if it gives them a specific advantage for survival. Birds evolved wings, because wings help you find food and evade predators, for instance.

Now, wheels may make perfect sense to you as you drive your Kia down the expressway, and one could well picture a wheeled caribou putting along right beside you.

But we forget that animals evolve in nature, which usually isn’t paved and smooth and flat like an expressway is. Nature is usually paved with some form of dirt, which is much friendlier to legs than wheels.

Try putting on roller-skates and proceed through the woods or across a prarie with them. You’ll soon see where the added weight, loss of traction for leaping over obstacles, and tendency for wheels to become jammed with sand, grass, etc. supercedes any benefit from having wheels.

Yes, your four wheel drive Hummer or an Army tank could negotiate the same territory with ease. But it’s powered by internal combustion, which, somehow, eludes mother nature in her quest to evolve the best-suited life-form. Which is to say, even if an animal had wheels, tank-treads, or other rotary locomotion device, it would still lack the means to supply power to those wheels…I’m picturing a huge dinosaur of a beast which eats corn and has a digestive set-up equivalent to being an ethanol processing plant…no, no, it’s all too complicated. Nature seems to prefer much simpler solutions.

A better question would be, since humans prefer paved/ tiled/ carpeted flat environments, how long will it be before humans evolve wheels? Having a stand of casters at the end of my spine, for instance, would elliminate the need to hunt the cubicles for my missing office chair…

Hoping I’ve put this discussion, whimsical though it be, to bed…

Hosiah

18

Speaking as a biologist, I’d say that the reason that wheels have not evolved is because it would be vanishingly rare that intermediate forms could survive. Weak explanations of evolution start with the current trait and then tell a “just so story” about it.

“Wings evolved because flight is an advantage.” Well, that might matter if wings and flight evolved all in one generation. Evolution doesn’t work that way. Instead, it seems that some tiny advantage was had when an already-feathered dinosaur had somewhat larger forelimbs, either helping it grab, balance, or hop. As these forelimbs got even larger, via selection, there was an additional, unforeseen bornus of being able to push off further on a jump or perhaps to extend the leap through a primitive glide with the pre-wings. However, if any stages had been disadvantageous, the animals would have gone extinct before their descendents got full-fledged wings and flight.

Wheels are so very much unlike any known or speculated multicellular animal body plan that there is probably far too much of a surviveability hump to get over in the intermediate stages.

19

One other argument against tripods:

A quadraped that loses a leg can still function, sort of. (We’ve all seen a three legged dog.)

But a tri-ped would keel over and die.

20

Why would it do that? I could provide just as strong an “argument” against bipedalism.