If I may be permitted a science fiction observation, this will be the major observation in the distant future upon encountering complex life forms in other galaxies. Despite impressive forms of intelligence and perceptual capacities, aliens will not very likely resemble those of our species. That, I suspect, will be when the last of our naive realists relent.
Maybe not even then
I liked that, JL, so allow me another possible (science fiction) scenario:
Maybe ALL species evolve in approximately the same way we have...and maybe ALL species arrive where we seem to be—with a technology advanced to the point where we can annihilate ourselves...BEFORE evolving philosophically to point where we are highly unlikely to do so. Maybe most often, whether accidentally or on purpose through wars, most species do destroy themselves before getting a chance to evolve much beyond where we are right now. Perhaps NO species (or very, very, very few) ever get much beyond where we are right now.
We MAY be one of the most advanced extant life forms in the universe, JL! The Reality may be that almost none ever gets past this dangerous period in what may be the normal pattern of evolution.
Maybe we will never have contact with extra-terrestrial species because “they” almost always destroy themselves before achieving the technology necessary to reach out to us…and/or because we will destroy ourselves before we are able to reach out to them.
Damn…it may be that all dominant species look relatively the same…or may deviate from one another significantly…and we will never know because the one thing we all possess in common is a tendency toward self-destruction.