Not to nitpick, but have we observed an eyeless organism evolve an eye?
That depends on what you mean by "observed." If you want to have
presented to you the video tape of the process, made live, then you
won't get it. But that is true of much of science and of most
everything else. We don't "observe" lot's of things that we accept as
non-controversial, because we know they take too long to be seen
within a reasonable time, or because they are too small to see
directly, or for any number of reasons.
But can we account for the evolution of an eye in an organism that
originally didn't have one? Most assuredly. For one very plausible
scheme, look at Richard Dawkins' book "The Blind Watchmaker." There
is certainly evidence in the fossil record of organisms that
developed "proto-eyes" and the progression of development along the
path from light-sensitive cells on the surface of the skin to the
well-developed eye of primates or several other animals that
developed them independently is pretty well-documented.
The problem with evolution as I see it is that the time scales that
we must deal with are extremely long--much longer than many people
are willing to accept--and guarantee that the record of what went on
will be spotty at best. It isn't amazing to me how little we know of
the record of our history, but how much, given how easy it is for
that record to be destroyed.
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