John Paul writes:
What is the intermediate between a single-celled organism without a nucleus and a single-celled organism with a nucleus?
Probably a symbiotic relationship between two single-celled organisms. Picture the nucleus as a parasite that when existing within another single-celled organism created a relationship that increased the overall survival advantage for the both of them.
What is the intermediate between single-celled organisms and multi-cellular organisms?
I don't think there necessarily needs to be one, although it could have gone something link: single-cellular --> bi-cellular --> multi-cellular.
True there are a variety of eyes but is there any evidence to show that one can evolve from the other?
We wouldn't necessarily expect to see a present-day eye evolving into another type of present-day eye. Instead, we would probably expect to see the formation of beneficial light sensitive organs of increasing specialization through time. I reckon light sensitivity was a major feature of the very first cellular organisms since even plants have developed their own specialization upon that ability.
Too bad the fossil record doesn't show anything resembling step-wise change. That is why punctuated equilibrium came about.
Yes, it is too bad, but with all due respect... so what?