Why didn't animals evolve wheels?

[Seth]

I still you are taking me too literally, nonetheless the double-joint at the shoulder allows you to sit in a chair and describe a circle with your hand down, up and behind, with a twist past your ear, and then forward again.

Look, I'm saying that this is merely analogous to the arc described by a point on the circumference of a wheel, not a wheel equivalent, and I'm raising this only as an example to counter the possible misapprehension that no such evolutionary process would or could take place because of the bio-mechanical impossibility of maintaining circulatory and nervous systems.

In other words, the example here is meant to exemplify a broader idea, that whatever the locomotive, anatomical or bio-mechanical features organisms evolves they are in response to the prevailing environmental circumstances at each generational iteration of the genome, where accumulated phenotypical traits secure or enhance the survivability of not just the species members which express them but the species as a whole, and is not a process limited by some arbitrarily predetermined design or engineering constraints.

As I've said already, it's hard to imagine an environment where wheelish appendages might be beneficial to an organism, even, perhaps, a flat, relatively frictionless low gravity one.

I would think it much more likely that the entire organism would roll like a wheel, or a ball, than to evolve an axle and bearings.

[JimC]

I still you are taking me too literally, nonetheless the double-joint at the shoulder allows you to sit in a chair and describe a circle with your hand down, up and behind, with a twist past your ear, and then forward again.

Look, I'm saying that this is merely analogous to the arc described by a point on the circumference of a wheel, not a wheel equivalent, and I'm raising this only as an example to counter the possible misapprehension that no such evolutionary process would or could take place because of the bio-mechanical impossibility of maintaining circulatory and nervous systems.

In other words, the example here is meant to exemplify a broader idea, that whatever the locomotive, anatomical or bio-mechanical features organisms evolves they are in response to the prevailing environmental circumstances at each generational iteration of the genome, where accumulated phenotypical traits secure or enhance the survivability of not just the species members which express them but the species as a whole, and is not a process limited by some arbitrarily predetermined design or engineering constraints.

As I've said already, it's hard to imagine an environment where wheelish appendages might be beneficial to an organism, even, perhaps, a flat, relatively frictionless low gravity one.

I would think it much more likely that the entire organism would roll like a wheel, or a ball, than to evolve an axle and bearings.

[NineBerry]

https://en.wikipedia.org/wiki/Rotating_ ... ng_systems

[Brian Peacock]

Yes, I got your message at least twice now. Still, the motion of the arm is not so much rotating as swinging and the ball and socket joint of the shoulder is nothing like an axle. The analogy to a wheel is too far fetched.

I have only repeated myself in response to responses, but the lack of a traditional axel doesn't stop you from wheeling your arms, your musculature acts as the fixed point. I think 'swinging' as a mechanism gives a completely different impression to 'rotation', one which doesn't adequately reflect the articulation involved.

As for countering the possible misapprehension that no such evolutionary process would or could take place because of the bio-mechanical impossibility of maintaining circulatory and nervous systems, yes, someone might possibly entertain such a misapprehension, but so far nobody seems to in this thread, and I certainly don't either. You keep repeating yourself as if someone has.

I'm simply repeating myself to qualify the misunderstanding of my previous remarks, and to point out that things like the absence of an apparently necessary axle is not necessarily a constraint to evolutionary processes.

[Forty Two]

There is no particular difficulty for evolution, or a species, here. If we look at the bio-chemistry of even simple life forms, like an amoeba for example, we can see that the apparent complexity of a system is no bar to evolution if-and-only-if the evolution of the system over time continues to secure and/or enhance the species' survivability.

The wheel is not particularly complex. It's merely that in order for a biological organism to exist, it requires energy and waste to be transported around. Inherent in the design of a wheel is that it spins. It spins around a center point. So, where do you connect the pathway where energy goes from the body to the wheel without it getting tangled up when the wheel spins?

It's not complexity, it's an engineering problem.

That may be why there are examples of very complex organisms, but no examples of organisms with wheels. It's not the complexity. It's a design barrier.

Maybe there would be a way to have, like, an organism roll on wheels, but energy and waste can move from the wheel unit to the body via some kind of osmosis. But, then you'd have a permeable membrane almost constantly exposed to the environment. Or, perhaps some form of symbiosis could form, where the wheel is a self sufficient entity that doesn't need food from the body. However, then the wheel would need its own way to get food intake and waste output.

You can't take veiny creatures, though, and put wheels on them because it would be like taking electrical wires and running them from the car engine to the wheel itself. As the wheel spins, the wires would get wrapped up around the axle and rip off.

There's no reason to think that a wheel on an organism has to work in the same manner as a wheel on a car. As you know, evolution doesn't work to a plan like that, and I've given the example of the human shoulder joint to highlight that this feature of hominid anatomy can produce articulated movement analogous to that of a wheel, although I have also pointed out that even given this evolution is driven by the interplay of environmental circumstance and the necessity of any such evolbed locomotive 'solution' having survivability benefits for any organism operating under those environmental conditions. My comments above were only intended to correct any lingering or implicit assumptions about the apparent functional necessity of 'hubs, axles and bearings' etc as being insurmountable constraints on, or barriers to, evolution.

I didn't say it had to work the same way as it does in a car, and in fact that's the whole problem.

And yet you did say...

Perhaps there is a difficulty in evolving a system of hubs, axles and bearings that can spin around without veins and nerves getting all twisted up on themselves.

Sure -- illustrating that if you're going to have veins, arteries and nerves, you can't have them getting tangled up in a spinning wheel.

... and ...

You can't take veiny creatures, though, and put wheels on them because it would be like taking electrical wires and running them from the car engine to the wheel itself. As the wheel spins, the wires would get wrapped up around the axle and rip off

... so I think my response is quite reasonable.

What response? That there is some way to do it in living creatures of which we cannot conceive?

... It simply can't work the same way that it works on a car. The wheels on a car don't need to sustain themselves. A living wheel, like a living foot, has to receive food energy and get rid of waste.

A shoulder joint doesn't spin round like a wheel, so all the veins and sinew don't get tangled up.

Something I have pointed out myself. Nor am I saying that the proposed evolved wheel should or must be like a shoulder joint. The human shoulder joint is merely an example of an anatomical feature with the articulatory flexibility to describe a circle on a vertical plane. I have acknowledged that in order to do this the arm also has to rotate along its axis.

The answer to the question of why animals did not evolve wheels, however, is that it's a thorny engineering problem that is not conducive to natural selection operating to attach wheels to living creatures. One reason is that all living creatures have to have systems to intake food and expel waste. How do you do that with a wheel without having tubes to get all tangled up, AND having a step by step evolutionary process by which you get from "no wheel" to "wheel."

Complexity is not the barrier -- eyes and ears can evolve, because every step of the way there are beneficial and useful advantages to the structures as they mutate and change. We can get from step to step to step to step in a long process of natural selection. With a wheel, though, that becomes difficult if not impossible to conceptualize how it could happen via natural selection and it becomes difficult to conceptualize how a biological wheel would actually work successfully.

The fact is that for living wheel to work, it has to function. Of course it doesn't have to have wheel bearings and antilock brakes. But, it does have to spin around and round. So, you need to attach the wheel to the body, and get it food energy and remove waste matter from the cells. With all other aspects of the animal body, food energy goes to the limbs via long tubes, and other long strands go there for nerves and such. the very act of spinning like a wheel makes wheels extraordinarily more of an engineering problem for living creatures than legs. Evolution would have to come up with a different way to fed the wheel organ, and remove waste products.

None of which I have disputed, except that we have the example of a human shoulder joint to show how such a mechanism could get around the problem of maintaining circulatory and nervous systems etc.

Except that it's not apples to apples, because shoulders don't spin around like wheels, so they veins don't get tangled up. Surely you see the difference. It's not an "example" of a biological system successfully getting around the engineering problem faced by biological wheels.

Maybe, for example, the connection could disconnect when the animal is going to roll. That is, you'd have like veins meet at a valve connector when the wheel is stationary, so blood can go in and out. Then, when the creature is going to move, the connection shuts and the veins disconnect and then the wheel spins and then they reconnect when the animal stops.

Maybe there is an osmosis thing where the wheel just sort of oozes stuff in and out.

Actually fleshing this idea out (see what I did there!?) isn't necessary, but if one were to indulge in speculation one might imagine something like a shoulder joint connecting to something like an arm housed inside some additional anatomical wheel-like framework.

Which would not be a wheel, and if it spun like a wheel it would have the same problem of the connective tissue, veins and arteries getting all tangled up.

What do you mean "fleshing out this idea isn't necessary?" How else can one suggest that it's possible if we can't even conceive of a workable solution?

For some reason, no such organisms have ever evolved.

For some reason eh? What do you think that reason is, or might be now I've pointed out, and indeed you have agreed, that it isn't necessarily a bio-mechanical, anatomical limitation?

The reason being the inherent difficulty in creating a biological system involving a wheel that doesn't get the mechanisms for feeding and getting rid of waste product, and nervous system, all tangled up when the wheel spins.

What do you mean I did not say it was a biomechaniscal, anatomical limitation? That's exactly what I did say. I said it was not an issue of "complexity." Wheels are not complex. But, if you're going to have a naturally selected wheel as part of a living thing, then you have to have natural selection move step by step toward the creation of a wheel wherein each step presents survival advantage or at least not disadvantgage, and which is able to solve the problem of how to have wheel spinning around while feeding it and eliminating waste.

That is a bio-mechanical and anatomical limitation.

[pErvinalia]

Something I have pointed out myself. Nor am I saying that the proposed evolved wheel should or must be like a shoulder joint. The human shoulder joint is merely an example of an anatomical feature with the articulatory flexibility to describe a circle on a vertical plane. I have acknowledged that in order to do this the arm also has to rotate along its axis.

The answer to the question of why animals did not evolve wheels, however, is that it's a thorny engineering problem that is not conducive to natural selection operating to attach wheels to living creatures. One reason is that all living creatures have to have systems to intake food and expel waste. How do you do that with a wheel without having tubes to get all tangled up, AND having a step by step evolutionary process by which you get from "no wheel" to "wheel."

Complexity is not the barrier -- eyes and ears can evolve, because every step of the way there are beneficial and useful advantages to the structures as they mutate and change. We can get from step to step to step to step in a long process of natural selection. With a wheel, though, that becomes difficult if not impossible to conceptualize how it could happen via natural selection and it becomes difficult to conceptualize how a biological wheel would actually work successfully.

I've already explained how it could work. It would seem terribly biologically/physiologically wasteful (and complex, of course), though.

The fact is that for living wheel to work, it has to function. Of course it doesn't have to have wheel bearings and antilock brakes. But, it does have to spin around and round. So, you need to attach the wheel to the body, and get it food energy and remove waste matter from the cells. With all other aspects of the animal body, food energy goes to the limbs via long tubes, and other long strands go there for nerves and such. the very act of spinning like a wheel makes wheels extraordinarily more of an engineering problem for living creatures than legs. Evolution would have to come up with a different way to fed the wheel organ, and remove waste products.

None of which I have disputed, except that we have the example of a human shoulder joint to show how such a mechanism could get around the problem of maintaining circulatory and nervous systems etc.

Except that it's not apples to apples, because shoulders don't spin around like wheels, so they veins don't get tangled up. Surely you see the difference. It's not an "example" of a biological system successfully getting around the engineering problem faced by biological wheels.

Shame you didn't read what I wrote. If you consider the arm a spoke, at the hand end you just need the same ball/socket mechanism as at the shoulder end. That allows the arm/spoke to rotate longitudinally in both directions, while still maintaining contact and all the wetware remaining intact.

[Forty Two]

Something I have pointed out myself. Nor am I saying that the proposed evolved wheel should or must be like a shoulder joint. The human shoulder joint is merely an example of an anatomical feature with the articulatory flexibility to describe a circle on a vertical plane. I have acknowledged that in order to do this the arm also has to rotate along its axis.

The answer to the question of why animals did not evolve wheels, however, is that it's a thorny engineering problem that is not conducive to natural selection operating to attach wheels to living creatures. One reason is that all living creatures have to have systems to intake food and expel waste. How do you do that with a wheel without having tubes to get all tangled up, AND having a step by step evolutionary process by which you get from "no wheel" to "wheel."

Complexity is not the barrier -- eyes and ears can evolve, because every step of the way there are beneficial and useful advantages to the structures as they mutate and change. We can get from step to step to step to step in a long process of natural selection. With a wheel, though, that becomes difficult if not impossible to conceptualize how it could happen via natural selection and it becomes difficult to conceptualize how a biological wheel would actually work successfully.

I've already explained how it could work. It would seem terribly biologically/physiologically wasteful (and complex, of course), though.

Sure, and I gave some ideas as well. The waste and difficulty of surmounting the structural design problem is the barrier. I think we agree.

The fact is that for living wheel to work, it has to function. Of course it doesn't have to have wheel bearings and antilock brakes. But, it does have to spin around and round. So, you need to attach the wheel to the body, and get it food energy and remove waste matter from the cells. With all other aspects of the animal body, food energy goes to the limbs via long tubes, and other long strands go there for nerves and such. the very act of spinning like a wheel makes wheels extraordinarily more of an engineering problem for living creatures than legs. Evolution would have to come up with a different way to fed the wheel organ, and remove waste products.

None of which I have disputed, except that we have the example of a human shoulder joint to show how such a mechanism could get around the problem of maintaining circulatory and nervous systems etc.

Except that it's not apples to apples, because shoulders don't spin around like wheels, so they veins don't get tangled up. Surely you see the difference. It's not an "example" of a biological system successfully getting around the engineering problem faced by biological wheels.

Shame you didn't read what I wrote. If you consider the arm a spoke, at the hand end you just need the same ball/socket mechanism as at the shoulder end. That allows the arm/spoke to rotate longitudinally in both directions, while still maintaining contact and all the wetware remaining intact.

Well, I'm not visualizing the design you're suggesting. Seems to me that if the veins and such are fixed at a point, and the arm spins, it can't roll without tying up the veins. I suppose you could use the shoulder joint, extend the arm out, and then have a round disc instead of a hand at the end of the arm, and then the wheel can rotate as the arm moves around and around.

In any case, fundamentally, we agree. I think the design ideas are hard for natural selection to evolve step by step.

[pErvinalia]

Yeah, the same joint at the hand end allows the arm to rotate longitudinally for half it's angular rotation and then rotate longitudinally back the other way for the other half of the angular rotation. Ridiculously complex, especially when compared to a simple leg.

[DaveDodo007]

Wheels are really good for moving around. So why legs, even in the insect kingdom....?

Apart from the biological constraints and such a method would still need some external propulsion, I haven't got a clue.

[Jason]

I haven't got a clue.

[DaveDodo007]

I haven't got a clue.

[JimC]

We could pare back the wilder speculations by limiting the OP to "Why didn't land vertebrates evolve wheels?", without ruling out the possibility in terms of beginning with wildly different body plans on an alternative Earth, or more reasonably, alien planets.

Once an initial tetrapod body plan was in place, the whole of the magnificent branch of the tree of life that followed involved was a series of fascinating variations of that basic design. With all its vast diversity, that fact imposes restrictions upon the possible directions - for example, there are no vertebrates with 4 limbs plus a pair of wings.

Given that we are restricting ourselves to a wheeled descendent of tetrapods on this current Earth, I agree with Forty Two that inherent engineering limitations mean that a wheeled vertebrate is simply not going to happen. By itself, this is enough as a reason without even mentioning the difficulties presented by the uneven terrain in most potential environments as a selective barrier.

You can't get there from here...

[Hermit]

...there are no vertebrates with 4 limbs plus a pair of wings.

Wrong.



Your regrettable ignorance of Pegasus mythyeri most likely stems from the fact that awareness of its existence has been displaced by the suffocating preponderance of Unicornus ubiquiti in popular awareness. As a science teacher you ought to know better.

[pErvinalia]

We could pare back the wilder speculations by limiting the OP to "Why didn't land vertebrates evolve wheels?", without ruling out the possibility in terms of beginning with wildly different body plans on an alternative Earth, or more reasonably, alien planets.

Once an initial tetrapod body plan was in place, the whole of the magnificent branch of the tree of life that followed involved was a series of fascinating variations of that basic design. With all its vast diversity, that fact imposes restrictions upon the possible directions - for example, there are no vertebrates with 4 limbs plus a pair of wings.

Given that we are restricting ourselves to a wheeled descendent of tetrapods on this current Earth, I agree with Forty Two that inherent engineering limitations mean that a wheeled vertebrate is simply not going to happen.

There aren't inherent engineering limitations as explained by Brian and myself. It could be done. It would just be so highly inefficient compared to legs as to be highly unlikely to evolve.

[JimC]

We could pare back the wilder speculations by limiting the OP to "Why didn't land vertebrates evolve wheels?", without ruling out the possibility in terms of beginning with wildly different body plans on an alternative Earth, or more reasonably, alien planets.

Once an initial tetrapod body plan was in place, the whole of the magnificent branch of the tree of life that followed involved was a series of fascinating variations of that basic design. With all its vast diversity, that fact imposes restrictions upon the possible directions - for example, there are no vertebrates with 4 limbs plus a pair of wings.

Given that we are restricting ourselves to a wheeled descendent of tetrapods on this current Earth, I agree with Forty Two that inherent engineering limitations mean that a wheeled vertebrate is simply not going to happen.

There aren't inherent engineering limitations as explained by Brian and myself. It could be done. It would just be so highly inefficient compared to legs as to be highly unlikely to evolve.

I beg to differ. If the wheel in question is to be supplied with nerves and blood vessels (an inevitable part of the vertebrate body plan), then free rotation is not just unlikely, but impossible. Start with a different plan (possibly an arthropod haemocoel), and impossible becomes merely unlikely.