system
Given the following post, respond as if you're commenting on Reddit:
human
Why are most living things roughly symmetrical?

Obviously no individual creature is exactly symmetrical, but all animals I can think of and all plants' archetypal arrangements are symmetrical. Is there some advantage to this common feature of organisms? Are there any notable exceptions?
gpt
Balance and the counteracting forces on all sides is built into symmetrical systems. Imagine if the organs of locomotion were asymmetrical. Your hypothetical organism would either have to spend a lot of energy adjusting its path and compensating for the different forces or it would travel in circles. 

Owl ears are a common example of asymmetrical structures. It is thought to aid in 3D acoustic discrimination. Also many crabs have specialized functions in each claw and large differences in size. These examples also require additional developmental programs to be built differently on both sides. Obviously symmetry (of different types- radial and bilateral are very common) was fixed very early on in the different groups and most organisms share this feature because they inherited it from a common ancestor. So now, there must generally be selection for asymmetry for it to arise (because there is almost always some selection against it via the mechanism mentioned above)