10 ms·

sure, bigger wheels and tracks can get you some greater percentage of navigable land, but nowhere near 100%. most terrestrial animals uses legs and not wheels f

sure, bigger wheels and tracks can get you some greater percentage of navigable land, but nowhere near 100%. most terrestrial animals uses legs and not wheels for a reason (and it's not because it's not evolutionarily possible). but yes, bigger wheels and tracks probably cover a greater percentage of the commercially viable landscape.

Robotbeat 6y ago
It is close to evolutionarily impossible to do a wheel and axle biologically. If the whole animal rolls, sure, but not a full wheel and axle (macroscopically). That is probably the main reason we see zero macroscopic animals with that configuration.
- clairity 6y ago
  biology on an evolutionary timescale is exceedingly clever, more ingenious than us humans. you don't need an axle, just something roundish (eyeballs or even pearls, for example).
  - thombat 6y ago
    The organism will need something like a fluid rotary union so the nervous and circulatory system can reach the rotating part, or that part will be limited to very low metabolic levels (basically diffusion). That will certainly be ingenious.
    - clairity 6y ago
      certainly, but biology is amazing. our muscles are basically chemical ratchets interconnected throughout a mosaic of levers (ignoring the complex control and feedback mechanisms, as well as the energy and waste systems, for a moment). also, your point is why i mentioned pearls--not all tissue needs to be activated or enervated similarly, or at all. we should have no doubt that biology would find a way given enough time.
      - Robotbeat 6y ago
        It has found a way! Through engineering. We invented wheels, and we’re a result of evolution. Dung beetles have engineered something similar, although no axle (yet).
  - Robotbeat 6y ago
    And yet it hasn’t happened! So I think that means there are fundamental reasons why it’s difficult for evolutionary processes.
  - squarefoot 6y ago
    That would be really really hard to achieve in nature. What about a millipede? To me they're the closest thing to a legged and a tracked-like creature. https://www.youtube.com/watch?v=xysbNbvUDZA https://www.youtube.com/watch?v=xysbNbvUDZA
- ggm 6y ago
  Not to invoke fiction as proof, but Philip Pullman hypothesized animals with a shiny claw which co-evolves with a tree making wheels. The claw evolves to be the axle and the tree evolves to make the wheels for co-benefit.
bsder 6y ago
> most terrestrial animals uses legs and not wheels for a reason (and it's not because it's not evolutionarily possible). Actually, I suggest its for exactly that reason. Rotary motion is sufficiently more efficient that if there was a way to evolve it, it probably would have. Rotary motion has lots of difficult issues: how do you power it, how do you communicate with it, how do you lock it in place, how do you reverse it? None of these are problems for stabilized linear actuators (aka muscles).
- clairity 6y ago
  that's exactly the limited engineering perspective to be wary of. biology doesn't consider those things, it just finds a way in a staggeringly multidimensional space of real consequences (also, muscles are just one, amazing, component of a holistic locomotory organism). rotary locomotion likely evolved multiple times over the eons and was outcompeted away by legged (and other) creatures with more mobility to find food and mates. for a potential analogue/precursor, consider the rotary joints we have in our bodies. legged locomotion has evolved to be quite efficient in certain ways too. human legs, for instance, evolved for walking/jogging long distances efficiently (we have 2 gait-dependent locomotory efficiency points at two different speeds). but we can also climb and run and kick and hop and swim and more when required, unlike rollers.
  - bsder 6y ago
    > rotary locomotion likely evolved multiple times over the eons and was outcompeted away by legged (and other) creatures with more mobility to find food and mates. Unlikely. Something that has the possibility to be so staggeringly more efficient would have found some niche even in present day. At least one spider makes itself into a wheel to roll down sand dunes faster than a predatory wasp can follow. When something as complicated and calorically expensive as vision can evolve multiple times, the fact that rotary power hasn't evolved says that there is a block somewhere. And, rotary power has evolved in some flagellar creatures. However, what evolved was a cellular ratchet. The system can go one direction only, and there was effectively no fine control for exactly the reasons I mentioned. > for a potential analogue/precursor, consider the rotary joints we have in our bodies. And those joints have complicated musculature and are relatively easy to permanently damage.

Robotbeat 6y ago

It is close to evolutionarily impossible to do a wheel and axle biologically. If the whole animal rolls, sure, but not a full wheel and axle (macroscopically). That is probably the main reason we see zero macroscopic animals with that configuration.

clairity 6y ago
biology on an evolutionary timescale is exceedingly clever, more ingenious than us humans. you don't need an axle, just something roundish (eyeballs or even pearls, for example).
- thombat 6y ago
  The organism will need something like a fluid rotary union so the nervous and circulatory system can reach the rotating part, or that part will be limited to very low metabolic levels (basically diffusion). That will certainly be ingenious.
  - clairity 6y ago
    certainly, but biology is amazing. our muscles are basically chemical ratchets interconnected throughout a mosaic of levers (ignoring the complex control and feedback mechanisms, as well as the energy and waste systems, for a moment). also, your point is why i mentioned pearls--not all tissue needs to be activated or enervated similarly, or at all. we should have no doubt that biology would find a way given enough time.
    - Robotbeat 6y ago
      It has found a way! Through engineering. We invented wheels, and we’re a result of evolution. Dung beetles have engineered something similar, although no axle (yet).
- Robotbeat 6y ago
  And yet it hasn’t happened! So I think that means there are fundamental reasons why it’s difficult for evolutionary processes.
- squarefoot 6y ago
  That would be really really hard to achieve in nature. What about a millipede? To me they're the closest thing to a legged and a tracked-like creature. https://www.youtube.com/watch?v=xysbNbvUDZA https://www.youtube.com/watch?v=xysbNbvUDZA
ggm 6y ago
Not to invoke fiction as proof, but Philip Pullman hypothesized animals with a shiny claw which co-evolves with a tree making wheels. The claw evolves to be the axle and the tree evolves to make the wheels for co-benefit.

bsder 6y ago

> most terrestrial animals uses legs and not wheels for a reason (and it's not because it's not evolutionarily possible). Actually, I suggest its for exactly that reason. Rotary motion is sufficiently more efficient that if there was a way to evolve it, it probably would have. Rotary motion has lots of difficult issues: how do you power it, how do you communicate with it, how do you lock it in place, how do you reverse it? None of these are problems for stabilized linear actuators (aka muscles).

clairity 6y ago
that's exactly the limited engineering perspective to be wary of. biology doesn't consider those things, it just finds a way in a staggeringly multidimensional space of real consequences (also, muscles are just one, amazing, component of a holistic locomotory organism). rotary locomotion likely evolved multiple times over the eons and was outcompeted away by legged (and other) creatures with more mobility to find food and mates. for a potential analogue/precursor, consider the rotary joints we have in our bodies. legged locomotion has evolved to be quite efficient in certain ways too. human legs, for instance, evolved for walking/jogging long distances efficiently (we have 2 gait-dependent locomotory efficiency points at two different speeds). but we can also climb and run and kick and hop and swim and more when required, unlike rollers.
- bsder 6y ago
  > rotary locomotion likely evolved multiple times over the eons and was outcompeted away by legged (and other) creatures with more mobility to find food and mates. Unlikely. Something that has the possibility to be so staggeringly more efficient would have found some niche even in present day. At least one spider makes itself into a wheel to roll down sand dunes faster than a predatory wasp can follow. When something as complicated and calorically expensive as vision can evolve multiple times, the fact that rotary power hasn't evolved says that there is a block somewhere. And, rotary power has evolved in some flagellar creatures. However, what evolved was a cellular ratchet. The system can go one direction only, and there was effectively no fine control for exactly the reasons I mentioned. > for a potential analogue/precursor, consider the rotary joints we have in our bodies. And those joints have complicated musculature and are relatively easy to permanently damage.