eye is to use see/light.
before the body evolute eye, the body should know there is light outside, so that we evolute eye to see light.
but without eye how do the body know there is light?
it is the same as ear.
ear is use to hear.
without ear we cannot hear. if we cannot hear, how do we know there is sound,
without knowing there is sound, how do the body evolute ear.
