You know, if you think about it critically, humans may be the least favorable evolutionary model so far.
Well, except for developing the ability to deliberately destroy itself, it's been successful so far (I think that's Sagan's point).
And, if you think about it, evolution doesn't seem to care so much for intelligence, especially self recognition type intelligence.
I think the jury is still out on that. AFAIK, there's no data to support your speculation.
"there's no data to support your speculation."
Yes, that is true. I was just throwing a thought out. It just seems that man has evolved the ability to self-destruct, which is probably a dead end road. But definitely not a scientific claim, just sort of a philosophical one.