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Dear
Dr. Universe,
Why are do so many people short sighted? In view of the amazing complexity of the visual perception apparatus the eye/brain combination achieves and the huge amount of brain function given over to sight, it seems surprising that such a simple and relatively easily corrected optical flaw should be so common. Why hasn't evolution selected this flaw out of our genes...or is it a relatively recent human problem related to our modern lifestyle?
Do you mean "nearsighted"? (Short-sighted means a lack of understanding, so if you want to know why people have so little common sense, I can't answer that!) I'll assume we are referring to vision. Well, that's a good question. It would seem that back at the beginning of homosapiens, having bad eyesight must have been pretty dangerous, thus being selected against. However, in modern day it is no longer selected against. It's not a problem. We rarely have to spot potential predators, and we definitely don't have to hunt prey to have something to eat. Furthermore, we have contacts and glasses to correct poor vision. So there really isn't anything to prevent nearsighted people from living to reproductive age.
Then how did this trait last into the modern age? I am sure it arises anew in lots of individuals, and is not a remnant of the very first human ancestors.
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