What type of biological life will more than likely be found on other planets?

Perhaps. And, with no substansive data (yet...) it's not like anyone can argue authoritatively either way.

My view aligns with the whole "from what information we do gather... Earth seems less and less 'unique' and more and more 'average'" idea.
Extrapolating with this view would lead one to believe that any trait that allows a species to dominate to a large degree is going to happen... sooner or later.

Swimming.
Flight.
Breathing air (or local livable atmosphere).
Intelligence.

Each of those is a huge factor and has led to total dominance of a large portion of the planet.

What do they require?

Water (...maybe just liquid?).
Air/Atmosphere.
Host.

Given those things... and limited resources where evolution will 'arms race' to take advantage of... I really only see it as a matter of time.

Was the development of intelligence on Earth fast or slow?

Again, if the history of Earth looking more and more 'average' rather than 'exceptional' is any indication... we can guess that we were likely not "fast" in becoming intelligent.

I would agree that using the central star for energy (photosynthesis of some kind) is a likely beginning for some sort of slow-growing, generally hardy life (like plants).

I don't know, of course. But my "naive sensors" start blasting angry noises whenever I try to think about humans being "the only intelligent life" in the entire universe. It's a big place.

Edited by Stile, : And he's across the finish line! But wait, it seems like he has forgotten the baton...

Agreed. I must admit that in my list of dominant traits intelligence is the baby of the group.
However, I would also say that Dinosuars were developing intelligence. Smaller raptor-like dinos were getting smarter. Would they ever develop intelligence as you're defining it here? I suppose that's impossible to know. My stance, though, is yes... they would have. It's not like mammals started from nothing. They got a good base from the dinosuars to start from. I don't see it as too much of a stretch to have the dinos actually continue on the intelligence path instead of mammals if we take away the asteroid or other disastrous occasion.

Point taken. I would say this is the largest blow to my position. If we look at the facts of human history (war escalation up to nuclear bombs and the ability to destroy the entire planet....), it almost seems inevitable that we will destory ourselves. Of course, there have been inroads of movement in the keep-the-peace side of things... but my arguement depends on looking at history and extrapolating into a straight line. If we take human's war history and extrapolate into a straight line... we're dead

I suppose "we'll see?" Or, more likely, we probably won't 'cause you and I will likely be long gone before any of this is figured out.

Ah... No, I don't mind the thought of being alone either. If there is other intelligence out there, and they're anything like us (currently)... it would certainly be safer for us to be alone, anyway... :]

Yeah, that would be cool.

It certainly looks impossible today. And maybe it is. I like to hope it isn't, though.
I'm sure that to many slaves and peasants that died as such in the past... that some of our current cities and social structures would seem like an impossible dream.
We're certainly not on the downhill slope of things yet by any means. There's a long way to go, and it may prove to be impossible. But we are making some progress, at least, and only building upon that foundation will allow us to continue.