<s>[INST] Why don't animals have wheels? Answer as briefly as possible. [/INST] Several organisms are capable of rolling locomotion. However, true wheels and propellers—despite their utility in human vehicles—do not seem to play a significant role in the movement of living things. First, there are several developmental and evolutionary obstacles to the advent of a wheel by natural selection. Secondly, wheels are often at a competitive disadvantage when compared with other means of propulsion. </s>