Joined: Mar. 2005
Even if we found a way to survey all the planets in this galaxy, and found that all (or at least a large majority) of intelligent species originated on planets from which astronomical observations could be made from the ground, what exactly would that prove?
Not that this is gonna happen any time soon, of course. Plus, explorers from Earth would be likely to be biased as to what kind of planet they surveyed, so there might be a tendency to ignore other kinds of planets even if the transportation costs were to go way down.