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AstroChuck's avatar

Why haven't animals evolved with wheels?

Asked by AstroChuck (37548points) June 23rd, 2008 from iPhone

When you figure how difficult it is to manufacture a robotic arm and how easy it is to construct a wheel, why hasn’t nature made an animal that has wheels for limbs?

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46 Answers

Babo's avatar

How do you come up with this stuff?

trudacia's avatar

interesting. For that matter, why don’t humans have wheels?

jrpowell's avatar

We have wheels. Or I might be the only guy to roll around on my testicles.

flameboi's avatar

Babo, I’m with you, astro, from where did u get this kind of questions, I mean… whoa, never wondered about that…

Seesul's avatar

Tire company conspiracy, Chuck, go watch Roger Rabbit (again) and analyze it with that in mind.

robmandu's avatar

A similar conversation from elsewhere, with the key differentiator that the folks there seem to have an clue as to what they’re talking about.

sebrowns's avatar

there are a few animals that employ wheels. probably the best known is the Mother-Of-Pearl Moth

robmandu's avatar

Whassat @sebrowns? A quick peek under the rocks and I cannot find any reference to the Pleuroptya ruralis moth’s use of wheels.

sebrowns's avatar

this is a random fact i picked up from an entomologist friend of mine. the wheel is apparently used by the caterpiller of the Mother-Of-Pearl Mothl. i am told that it is apparently quite a feat to behold! a quick google produced this…

” Now the only known land creature that will deliberately itself roll away from danger is the caterpillar of the Mother-Of-Pearl Moth, Pleurotya ruralis. This research was done by John Brackenbury at University of Cambridge in the United Kingdom. Most caterpillars have some sort of defence against attackers – such as a warning set of colours, irritant hairs, or chemicals that make them taste really bad. The mother-of-pearl caterpillar doesn’t have any of these, so it relies on rolling away at enormous speed.

These caterpillars have a body made up of thirteen segments. They have legs attached to each of the end segments, as well as four sets of legs in the middle on segments 6 to 9. When they’re walking forward, you can see the characteristic travelling “hump” or “wave” move along the caterpillar’s back. As the wave comes along, it lifts a segment up from the ground, squashes it into the segment in front of it, and then lowers it back down on the ground. In each cycle of taking one step forward, each foot is on the ground 65% of the time. So each foot spends most of its time on the ground. This does make the caterpillar very stable, but it also stops it from walking rapidly. This is why caterpillars walk so slowly – only about one centimetre per second, or one tenth of the speed of other insects of the same weight.

But if you provoke it by poking it on the head or chest, things get interesting. If you give it a mild poke, it will walk backwards. This backward walking looks exactly the same as the forward walking, except it’s in the opposite direction.

If you give it a medium poke, the wave will move across its body much faster, the legs will spend more time in the air, and it will actually retreat from you at a fast gallop.

But if you give it a really good poke, it will start off in its reverse gallop, and then, with its tail on the ground, push off from its front legs, curl itself into a ball, and roll backwards. Depending on how flat and level the ground is, a decent push will set it off into five complete revolutions, travelling at a speed of about 40 centimetres per second – about 40 times its normal speed.”

robmandu's avatar

That is pretty cool… and not dissimilar in concept to the armadillo.

To my way of thinking, that is less of a wheel and more of a ball. (Granted, for the caterpillar, it’d be a rather two-dimensional ball).

Seesul's avatar

And here I thought the trivia trap in my brain had nearly reached capacity, sebrowns and rob, but it just expanded with that last banter. Whew!

Seesul's avatar

@ Babo: I wondered the same thing until AC disclosed his job. My theory is that it keep s him from going postal from carrying all of that junk mail around…and we are all better for it.

bluemukaki's avatar

@sebrowns: Hooray for ABC Australia!

breedmitch's avatar

I’d postulate that humans (at least) haven’t evolved wheel-like limbs because we instead invented wheeled modes of transport. Evolution can be a drastic step for a species and since we already had wheeled vehicles, we chose to use that energy evolving in another way. (Like voting for candidates who support equal marriage rights)

bluemukaki's avatar

@breedmich: Wouldn’t it be the other way around? I doubt we’ve evolved (or lack-thereof) much since wheels were used for transport on the massive scale we see today, the technology was made to facilitate our lack of wheels, our need for wheels.

Seesul's avatar

If we had developed wheels, wouldn’t everyone be more round? Isn’t that why a lot of people are getting more round? (Nothing personal Babo, you’re a cute round).

Harp's avatar

Evolution doesn’t favor simplicity. In fact, this study showed that it pretty much always tends toward complexity.

cage's avatar

Because wheels probably aren’t the most effective form of transportation. Wheels are very hard to move over rough ground. Simple really. and anyway, we have axels! (Ball and socket joints allow rotational movement around one point, just like wheels)

breedmitch's avatar

@bluemaki: What I’m saying is that because we invented the wheel, evolution was able to say “Oh, look! Now I don’t have to waste my energy doing that. Let’s concentrate on having them all love each other equally, instead.”
uh-oh. My evolution is starting to sound like intelligent design! ;)

bluemukaki's avatar

@breedmitch: and I’m saying that evolution wouldn’t work like that. I’m also saying that technology has filled the gap between our capabilities and our evolution, but it hasn’t been around long enough to not evolve because of our use of cars etc. There is a simpler reason we haven’t evolved with wheels and that’s they dont facilitate multiple gaits, jumping, swimming or climbing which were more important for our survival.

breedmitch's avatar

@bluemaki: I understand you.

hannahsugs's avatar

A true wheel has two interlocking parts, the wheel and the axle. While the moth above rolls, it’s hard to say that it is using a wheel, i agree with Robmandu that it’s more of a rolling ball than a wheel. It’s evolutionarily very improbable that a creature would develop a functioning wheel, because issues of blood supply to the detached wheel part would be very difficult.

The third book of Phillip Pulman’s “His Dark Materials” series, The Amber Spyglass hypothesizes an animal that has evolved the use of wheels by using giant seed pods as the wheels and the animal’s legs as the axles. This might be theoretically possible, I suppose, but the tree producing the seed pods and the animal using them would have to evolve together in a very closely related way. However, evolution tends to function in small increments, with the eye probably first appearing as a general light-sensor, and gradually being able to focus an image, because a slightly in-focus image is better than undifferentiated light, and slightly more in focus is even better, etc. I can’t imagine this working for a wheel, because there has to be some sort of basic starting point, but there’s not really any such thing as a wheel that almost works, it either rolls or it doesn’t!

sorry for the run-on sentences, I usually try to write more clearly, but I’m short on time!

AstroChuck's avatar

You could have blood pumping through a central axle and thus into the middle of the wheel. Or the “wheel” itself could be made up of dead cells. Some bacteria have wheel like propellors with a continuously rotating shaft, not in situ. There are other ways around these problems with in situ wheels in larger creatures. But perhaps some of you are right. The simplest things to construct might end up being the most difficult for nature to create.

buster's avatar

I don’t know why but I would love to have a dog with four-wheel drive. Im just glad animals havent evolved into more sluglike creatures yet.

Knotmyday's avatar

I can imagine a wheel structure made of keratin, with a muscular locomotive structure as axle/motor, lubricated by mucous.
A big, round, slimy spinning thumbnail, to be precise.
But as bluemukaki pointed out, such a structure would be ill-adapted to survival on Earth.
Might be more appropriate on a planet with a higher gravitational pull.

shrubbery's avatar

hannahsugs, I was going to talk about what you did but you beat me to it, fantastic answer, I love those books. I think bluemukaki has the best theory.

damianmann's avatar

The whole purpose of inventing wheels was the fact that they aren’t a natural part of our s, or any other creatures, evolution. They were invented because they were needed.

ben's avatar

Some great answers here. I think cage is onto it. Here’s my take:

Wheels required roads. Without roads, wheels really aren’t that useful. Legs can run, climb, maneuver over almost any terrain.

I agree with the axel/motor stuff, too. But I think if animals evolved alongside level road-like surfaces, they would have wheels.

Great question!

AstroChuck's avatar

I don’t know about that. (Please forgive me, Fluther god.) An animal with wheels might make one hell off a predator on the savannah. A crude organic wheel should be able to handle the odd bump or dip, I would think. Sir.

ben's avatar

Yeah, I was thinking about the savannah, that’s a good point. But I still thing it’s a lot different than a road. It’s harder to get over a bump with a wheel than you might think. That’s why tanks (and some robots) use “tracks” instead of regular wheels.

But yes, it’s still an intriguing question.

And please don’t be shy challenging me just because I co-Founded this site. Really. :) That goes for everyone.

bluemukaki's avatar

@Ben and AstroChuck: I also think from a technical/biological point of view that a wheel type structure would be difficult to develop in an organic organism at a larger scale (like humans and Rhinoceroses), the only examples we have for this in nature are where a creature is literally rolling itself into a wheel shape, which is still not exactly a wheel. Imagine seeing a Lion rolling towards its prey and dragging off against buffalo!

sebrowns's avatar

my conclusion is that other forms of locomotion are “superior” to the wheel in nature. the wheel was never utilized by organisms because it has never conferred a selective advantage. keep in mind that the wheel has existed for maybe 8,000 years while other forms of locomotion are 3×10^9 years old! from this perspective, the wheel is an arcane man-made invention that comes nowhere close to the sophistication of nature’s locomotive methods (flagella,siphons, wings, legs, etc.)

perhaps the more interesting question is why humans choose the wheel instead of choosing a form of locomotion that pre-existed in nature. interestingly, the wheel was invented at least twice independently – once in north america and once in europe. clearly for human society the wheel did yield a selective advantage by facilitating a conversion from hunter/ gatherer to agricultural societies. similarly, the wing was independently invented in several animal lineages such as in an ancestral arthropod and mammal presumably allowing access to new food sources and/or predator evasion.

waterskier2007's avatar

@ben. i think that is where you are wrong, correct me if im wrong but werent wheels invented before roads? i mean the roads were made because wheels were invented.

AstroChuck's avatar

There were likely foot trails before the wheel came around. Now humble yourself before our god. Don’t make eye contact with his avatar, but look toward the ground and kowtow. Then go light a candle.

El_Cadejo's avatar

Nannosquilla decemspinosa lies on its back, curls its tail up to its head, executes a neat flip and starts over again. Caldwell found one particularly energetic stomatopod that somersaulted for more than 6 feet. Although one species of spider is known to fold into a ball and roll down sand dunes, N. decemspinosa is the only animal known to wheel itself over level ground, or even uphill. ”

You can read more about it in this article (the wheel part is at the bottom)

Knotmyday's avatar

I find it interesting that Native Americans (North, Central, and South), despite their engineering prowess, never developed wheeled vehicles for transportation.

The Aztecs, Mayans and Incas all built large causeways which hadn’t been touched by a wheel pre-European invasion.

Arglebargle_IV's avatar

think of the climate and landscape of Central and South America! it is so wet and mountainous that roads are much less practical than on the plains of Spain.
animals can roll up into balls but they can’t rotate an axle because there are no smaller parts to scale-up for the task. isn’t that how mother works?
...although, I do seem to recall some scurrilous rumour that bacterial flagella might be rotating a corkscrew, rather than flicking a whip.

AstroChuck's avatar

Maybe you recall it from this thread.

wilhel1812's avatar

You should read The Amber Spyglass
the animals in that book rocks!

RocketGuy's avatar

Maybe the “Intelligent Designer” has never stepped in to make that design leap to wheeled motive mode. Hey, maybe there is no “Intelligent Designer” in the first place!

andrew's avatar

richardhenry just showed me this. Amazing!

breedmitch's avatar

@andrew: That visual is absolutely wild!

andrew's avatar

Actually, that link that @robmandu posted gives the most compelling argument I’ve seen:

An actual wheel would require and entirely free rotational component (as @hannahsugs talks about). I’d think that the energy costs for trying to provide bloodflow would be prohibitive—so any efficiency would be neutralized.

wilhel1812's avatar

Let me see if i can explain this with my English…
In The Amber Spyglass, there is animals called Mulefas, that uses some kind of disc-shaped seed pods. They attatch their claws from the front and rear feet inside the center of these and uses their middle feet to gain speed. A picture says more than 1000 words…

I imagine something like this could happen!

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