Has there ever been any evidence (as in the fossil record for example), of living creatures ever evolving wheels instead of legs?
What would be necessary (as far as sockets, blood supply, etc.) for a hypothetical living creature to have these biological wheels?
I imagine there’s a lot of biological pressure against wheels. They don’t appear to work well in certain terrains, and if one of them breaks, it seems like it’d be worse than with legs.
Len
Daughter asked me to add this (for no reason): :smack:
I don’t think there is a “why not”. They just didn’t.
Though we can postulate on many good arguments against the idea of wheels evolving, I think, of all creatures, the exo-skeletal ones like crabs or insects, could’ve evolved a freemoving loose part of their body somehow, such as a ‘foot’ that is attached to the leg by a hooplike limb. That would essentially be a wheel.
But it hasn’t happened that we have discovered, so that’s that. It’s not like evolution deliberately tries every possibility and then rejects things through any logical considerations. A lot of the time, things just are or they aren’t.
It may well be possible to create a creature with wheels. It would not be suitable for any natural terrestial environment except maybe some deserts. And leaving aside difficulties in forming the wheels, there’s always the issue of breakage. Not only would the wheeled ceature become totally immobile, there’s no good way to heal a free-standing part. It probably couldn’t have a good blood flow if any.
There is a spider in the desert that can form its body into a wheel to escape predators, obviously it can only escape downhill.
Ah, but that’s not quite the same as having a wheel for a body part, permanently.
Well, since you do specify hypotheticals, I feel comfortable discussing fictional creatures in a GQ thread.
In particular, the Mulefa from Pullman’s His Dark Materials series, which use naturally occuring organic wheels for locomotion.
The pods in question are enormous perfectly round seedpods from the dominant species of tree on a planet covered in road-like lava flows strewn about enormous grasslands. The Mulefa have evolved to use them by using claws as axles and these seedpods as the actual wheels, allowing themselves to scoot around at great speed along these ‘roads’. When the pod finally breaks or is worn out, it’s discarded to sprout another tree, and a fresh seedpod is found. There’s also something about an oil used for lubrication, which I don’t remember much about. Maybe they secrete it from glands or something.
The point being that, at least theoretically (inasmuch as SciFi/Fantasy counts as such) it is possible to have wheeled living beings.
I can also imagine a sort of creature which grew its own wheels using horn, chitin, mother-of-pearl, or whatever it is that you call that stuff that snails make shells out of. Perhaps have several growing at once, and only use the outermost one, so when (not if) it breaks it can be easily shed and a new one ready to replace it.
Of course, the question of how something like this could evolve… well, that’s a little more complex, isn’t it? ;j
If it’s part of your body, it needs a blood supply. (as well as a return…artery AND vein) Getting blood to a rotating member would require structures probably not found in nature. Engineers do this sort of thing, but nature doesn’t seem to have evolved the tricks they use.
Good argument agains ID, BTW…along with that wet drippy upside down thing located over our mouths.
According to this site,
http://www.bms.ed.ac.uk/research/others/smaciver/Cell%20biol.topics/Cell_Locomotion.htm
there are bacteria that have a true wheel as a body part.
Interesting. Regarding the lack of evolved wheels, is it the wheel or the transmission mechanism that’s the sticking point? I’m thinking a circle shape isn’t particularly difficult to evolve, but the biological equivalent of a Tiptronic might be.
Len