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I was thinking why is that so, why Uchihas go blind while Hyuga feel no side effects from using byakugan? (Aside of that fact that Kishimoto loves Uchiha clan, so they expirience the most angst and suffer)
And I have had one semi-biological conclusion.
So, some of you may be familiar with the theory that people have a lot of diseases that develop with age or appear in old age because that's how evolution and natural selection work. In other words, most people manage to pass on their genes to the next generation (that is, become evolutionarily successful) before they get diseases that most often appear at a certain age. Evolution filters out those mutations that are incompatible with reproduction, because it is through reproduction that all living things fix useful traits and pass them on. Accordingly, evolution has almost no effect (or it happens by chance) on traits that do not prevent a person from successfully surviving to pass on their genes to their children. If an individual lived to have children, it is already a biologically successful individual. Then you can die. Evolution is cruel and unempathetic.
I looked at the sharingan from this side. From the evolutionary side. Sharingan as a biological trait should take a very long time to form, mutate and change in the process of evolution. He would improve due to the fact that the Uchiha with the stronger sharingan would successfully survive and reproduce. But at the same time, evolution would no longer affect what would happen to the Uchiha's eyes after they would produce offspring at a young age. Since the genes have already been passed down, the next generation will have the same trait as the parents. Regardless of what happens next with the parents. So since blindness was not a trait that would have prevented the Uchiha from living to reproductive age, it was not weeded out by evolution in any way. In conclusion, we have a biological trait that was evolutionarily strengthened and developed, because the ability of the Uchiha to survive depended on the power of the sharingan. Uchiha with a weak sharingan died before they could have children. But the gradual loss of vision did not interfere with the clan's survival, so it was not evolutionary screened out. In this way, the sharingan was formed, which is an incredibly useful and powerful trait, but at the same time, evolution did not affect the subsequent loss of vision. Blindness isn't biologically disabling, so the Uchiha's DNA doesn't have to mutate to compensate for it. Uchih's eye blindness is just a biological process, a consequence of the fact that there was no evolutionary stimulus in their eyes to compensate for it. The Uchiha with the strongest sharingan became reproductively successful, but subsequent vision problems did not affect this. Evolutionarily, there was no need for the sharingan to find a middle ground between power and not straining the eyes and going blind as a result. Evolutionarily, their eyes improved the power of the Sharingan, but did not improve endurance. Therefore, the Sharingan is an incredibly powerful force, but there is no mechanism to overcome the consequences of using it.