[jerf]

More generally, a certain amount of humility and skepticism about these issues is good, but I have almost a pet peeve sort of relationship with people who think we must profess total ignorance. We really don't. If they live in this universe, they play by the same rules we do, and that will shape them every bit as much as it does them. While I have no reason to believe that in the style of pulp sci-fi we will stroll out into the universe to find a universe of interbreedable humanoids, there's really no reason to believe that we will understand nothing about the aliens.

In fact it's sort of a violation of the general Copernican principle... we are not so special that we will be uniquely unable to understand anybody else. We are, probably, fairly normal.