I understand why we feel pain- it lets us know that something is wrong physically, which is especially useful if the injury is one that we can’t see. Is there a reason for an itch? And what is the difference, physiologically, between pain and an itch?
Now I might be wrong, but I seem to recall that an itch is an irritation of the nerves that sense touch, while pain receptors use different nerves.
Of course, I might be totally out to lunch on this one…