<|im_start|>system
You are a helpful AI assistant.<|im_end|>
<|im_start|>user
Why don't animals have wheels? Answer as briefly as possible.<|im_end|>
<|im_start|>assistant
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.<|im_end|>
<|im_start|>user
Why is it difficult for wheels to occur naturally in animals? What are those evolutionary obstacles?<|im_end|>
<|im_start|>assistant
Wheels are a highly specialized and complex structure, and as such, it is highly unlikely that they would have evolved naturally in animals. Evolution of wheels would require development of a special skeletal structure and joints capable of supporting an animal's weight and allowing it to rotate muscles and tendons to drive wheel rotation, probably at a considerable cost in terms of survival and reproduction. Lastly, the wheel is a human invention, very useful in some circumstances, but the result of human ingenuity and technology rather than natural development.<|im_end|>
<|im_start|>user
For the organisms that are capable of rolling locomotion, how do they move that way without wheels?<|im_end|>
<|im_start|>assistant
Organisms that are capable of rolling locomotion use different mechanisms to roll without wheels. Some examples include:

Ball-rolling animals: Some animals, such as the pill millipede, roll into a tight ball as a defense mechanism.
Armadillo-like animals: Some animals, such as the armadillo, can roll into a tight ball for protection.
Rolling fish: Some fish, such as the barreleye, can roll their eyes to change the direction of their gaze.
Rolling insects: Some insects, such as the dung beetle, can roll a ball of dung using their legs.
In summary, organisms that are capable of rolling locomotion use a variety of mechanisms such as ball-rolling, armadillo-like rolling, rolling eyes and legs to move without wheels.<|im_end|>
<|im_start|>user
Elaborate pls<|im_end|>
<|im_start|>assistant
Animals do not have wheels because they have evolved to move in different ways that are better suited to their environments and survival needs. For example, animals that live in forests and rough terrain often have four legs that allow them to walk on uneven ground and climb trees. Animals that live in water often have fins or flippers that allow them to swim efficiently. Additionally, wheels are a man-made invention and don't occur naturally in the animal kingdom, in the same way, it doesn't occur in the plant kingdom either. Evolutionary pressure has led to the development of different forms of movement and structures, such as legs, fins, wings, etc. that are better suited to the environments in which different species live.<|im_end|>
<|im_start|>user
Is it possible to create experiments to grow wheels on animals instead of legs?<|im_end|>
<|im_start|>assistant
It’s not fundamentally impossible to have wheeled creatures, but there are a number of different answers. The technical problem with making a biological wheel is blood supply. If you want to have a wheel, somehow you need to connect it up to the blood, and that’s an extremely hard engineering problem. You also need to provide some method of propulsion, although that could be done like a scooter, using other limbs to propel you along.<|im_end|>
<|im_start|>user
Oh, that's sad. On another note, there were animals invented by humans?<|im_end|>
<|im_start|>assistant
Oops! I was wrong earlier: No animals have been invented by humans. Humans have definitely modified animals through selective breeding and genetic engineering, but these actions hardly amount to something like inventing, which typically implies designing and creating product from the ground-up.<|im_end|>
<|im_start|>user
Why did evolution never come up with wheels instead of legs?<|im_end|>
<|im_start|>assistant
Evolution is a process that occurs over millions of years and is driven by the survival and reproduction of organisms that have certain advantageous traits. The development of wheels as a means of locomotion would have required significant changes to the anatomy and physiology of animals, and it is possible that legs, which are a more versatile form of locomotion, were more advantageous for the survival and reproduction of ancestral species. Additionally, the development of wheels would have also required a hard surface to roll on, which may not have been available in many environments where early animals lived.<|im_end|>
<|im_start|>user
Which animals have been invented by humans?<|im_end|>
<|im_start|>assistant
Several animals have been created by humans through traditional breeding methods and more recently through genetic engineering. Examples of animals created through traditional breeding methods include the liger (a hybrid of a male lion and female tiger), tigon (a hybrid of a male tiger and female lion), mule (a hybrid of a male donkey and female horse), and beefalo (a hybrid of a male bison and female domestic cow). A few examples of animals created through genetic engineering include the GloFish (a type of zebrafish with fluorescent colors), the Enviropig (a pig with an altered digestive system), and the human-rat hybrid (a hybrid of a rat and human embryonic stem cells).<|im_end|>
<|im_start|>user
Can you explain it in terms of evolution / Natural selection, and not philosophically?<|im_end|>
<|im_start|>assistant
Animals do not have wheels because they are not evolutionarily advantageous for most animals. Wheels are a man-made invention that has specific uses in certain environments. Still, in nature, the ability to move in different terrains and adapt to changing conditions is critical for survival. Additionally, a wheeled structure would require significant energy to maintain and move and would be vulnerable to damage in rough terrain. Evolution has favoured forms of movement such as legs, fins, and wings, which are more versatile and efficient for most animals.<|im_end|>
<|im_start|>user
Your answer is too short, write at least 10 sentences that go more in depth in the explanation<|im_end|>
<|im_start|>assistant
Animals do not have wheels because it is difficult for them to evolve. Animals evolve over time because of natural variation in their genes. Animals that have beneficial variations are more likely to reproduce and so beneficial genes become more prevalent over time. Usually these changes are small and gradual. For an animal to have wheels, it would be a very large change for several reasons. One of these is that most animals have a circulatory system that provides oxygen, nutrients and hormones to the body. In order to have a wheel that rotates on an axel, the wheel and axel must be disconnected so the wheel can rotate freely. There is no clear way for the circulatory system to provide nutrients to a wheel if it is completely separate from the axel. Any veins or other connections to it would become tangled up as it rotated. That is my best explanation as to why wheels haven't evolved in animals.<|im_end|>