Is Evolution Reversible

Didn't you just answer your question? If evolution doesn't have a direction, then going backwards is a contradiction in terms, as "backwards" is indicative of being directional.If evolution simply means, "change," then there is no forward or backwards, just different.If you are asking if humans can somehow devolve back in to single-celled organelles, I would think not.

I was under the impression that he was hinting of going back very far on the lineage. I'm wondering just how far "backwards" he was referring to. But I tend to agree with you that selective pressures + isolation + mutation does all sorts of weird things. I would think that whatever adaptations evolved could just as easily go back via deletion/insertion.But Dr. Adequate is right in that a significant nucleotide change would kill an organism before it gave it a chance to populate further. Somewhere in the order of three base changes, maybe? I don't know. I think in practical terms it would be unremarkable, such as the Galapagos finches you spoke of.

I stand corrected.

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"An idealist believes the short run doesn't count. A cynic believes the long run doesn't matter. A realist believes that what is done or left undone in the short run determines the long run." --Sydney J. Harris--