<s>[INST] Why don't animals have wheels? Answer as briefly as possible. [/INST] Mechanistically because wheels are a human invention, and only a few animals have been invented by human. In general current modern technology is quite bad mergine biological and mechanical components in a way that is consistent with the animal's fitness curve. If by having wheels you mean only figuratevely, then domestic animals often have prostetic wheels as a consequence of surgeries and congenital problems which serverly impair their deambulation ability.</s>\ <s>[INST] Why did evolution never come up with wheels instead of legs? [/INST] Animals were prevented from evolving wheels, some biologists reason, by following dilemma: Living cells in animal's body are connected to the heart by blood vessels, and to the brain by nerves. Because a rotating join is essential to a wheel, a wheel made of living cells would twist its artery, vein, and nerve connections at the first revolution, making living wheels impracticable.</s>