The wheel is a ubiquitous tool in the human world and it is inconceivable to imagine how the modern world could function in their absence. Wheels are an efficient means of locomotion and given a power supply allow puny bipedal humans to travel faster than the fleetest of animals. All this raises the question- why haven't animals evolved wheels rather than the preposterous gangly appendages called legs? Good question Flaxen, and well stated.
The greatest engineers are animals; many of our inventions were first anticipated in animals. Wings for flight and echolocation in bats; night vision in cats; electric fields in eels and SONAR in dolphins, but not an axle or rotating wheel in sight/site. There is one exception, I suppose, but it occurs in bacteria, so not an animal at all, but certainly a living creature. Many bacteria propel themselves in water by means of a whip-like appendage called flagella. Flagella rotate freely on an axle which passes through the cell wall. The fact that multi-cellular organisms have not evolved larger versions of the unicellular 'wheel' is revealing. Biologically speaking it would be difficult to develop a free moving wheel. All limbs and organs require a blood supply for oxygen, nutrients and energy. This necessitates an attached, continuous circulation with conduits (veins and arteries). How could this occur in a wheel like object without severing the life line every time the wheel moved? The same thing would apply to nerves and other support structures.
Is the wheel really the most efficient means of travel? It certainly allows speedy perambulation, but it is not on all terrain solution. Wheels require smooth surfaced roads. Wheels don't work too well on rocky, swampy and rough land. But legs do. Legs are remarkably efficient at negotiating all types of terrain. Some animals are incredibly efficient at traversing rough ground- enter the mountain goat, stage left. So, if the wheel could evolve, which I suspect it can’t for reasons outlined above, it would have to be preceded by the evolution and adoption/adaptation of the road. Not as daft as you might think. Animals can be very adept at making quite sophisticated structures. Behold the ant-hill and the beaver’s dam. From an engineering perspective, road building is relatively simple and I'm sure, technically, within evolution's grasp, if it could be bothered. As outlined by Richard Dawkins, a trait can only become established by evolution if it confers an advantage (ultimately a reproductive advantage), to an organism, at the individual level. Evolution should never be viewed at the level of the species as originally espoused by Darwin, it can only occur at the level of the individual and to be evolutionary successful individuals need to be selfish and deny resources (whatever they may be) to competitors of the same species. This is why territories, nests and dams work- they are defensible and therefore, work for the maximum good of the builder. Roads are not defensible and can be used by any lazy individual who comes along. Road building is an evolutionary dead end. Any creature deciding to build a road would have to put a great deal of energy and resource into the enterprise, this is only worth it if it confers a reproductive fitness advantage. The strategy is exploitable by the lazy parasitical opportunist and it is impossible for the builder to deny access to its competitors. The opportunist need not apply any energy and resource into building and would reap the reward of the industrious builder and consequently would have more time and energy for reproductive success thus outcompeting the dedicated and exhausted road maker. Therefore, the evolution of road building and consequently wheel making, even if it was biologically feasible, could not occur, because from an evolutionary standpoint, it is an exploitable strategy. Selfish strategies are always rewarded by evolution until a counterstrategy, by selfish evolution, prevails.
And thus the wheel of evolution continues to turn with aplomb……… (Flaxen, for god's sake start taking the blue pills, as directed). Arse.
'There's a green one and a blue one and one with a bit of poo on, and they all taste just the same.'