In real life it's a lot worse than that. In real life, assuming you somehow magically evolved the first such feature, then by the time another 5000 generations rolled around and you evolved the next, the first, having been anti-functional the whole time, would have de-evolved or become vestigial.
Consider that flying birds are supposed to have evolved from small velociraptors having none of the needed features.
Consider also the common chicken; chickens are not too big to fly well, ducks and geese which are larger fly perfectly well. Chickens started out as a 1.5 lb jungle fowl and then were BRED into a five or six pound bird, but they still have the 1.5 lb bird's wings, which is why they do not fly any better than they do.
Nonetheless, compared to the velociraptor bird wannabe which started out with no such features and a tiny numeric base, chickens the flight feathers, the wings, the flowthrough hearts and lungs, the light bones, the necessary balance parameters and conformation, and basically all but the very tiniest bit of what it would take to regain the skies.
If the velociraptor's journey to being a flying bird is a thousand miles, the chicken only has an eighth of an inch to cover and evolutionary theory demands that somewhere over the last five or ten thousand years out of all the chickens which have ever gotten loose, some should have regained whatever is lacking for full flight capabilities and retaken the skies. We should see chickens when we look overhead.
But we do not. In real life, if you ever lose the tiniest bit of come complex capability or for whatever reason fail to have it, that's the end of the story. You'll never see it or see it again.
It's like cutting hair. It's relatively easy to cut it off, while getting it back on again is impossible.
This statement is utterly fatuous. Domesticated chickens can't survive in the wild, much less reproduce to the point where anyone would notice. I know this never made any impression on you when you posted as "Medved," but why make the same silly mistakes when you're tomzz?
What's next? A re-run of your minstrel dialect act and telling us how much you loved Amos 'n' Andy?
"It's like cutting hair. It's relatively easy to cut it off, while getting it back on again is impossible."
That may be the weakest analogy I have heard on this subject! Congratulations!
I don't know about you, but I wish it were true. Then I could save all that money every month getting it cut again after IT GROWS BACK!!!!