<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>\ <s>[INST] Why is it difficult for wheels to occur naturally in animals? What are those evolutionary obstacles? [/INST] There would need to be a way to bring in nutrients and get ride to the wheel body part. The wheel would spin and not be able to move resources and waste around.</s>