Help with alien theory (please?)

Hey guys, I've had this theory for a while, and I was wondering if anyone could rip it to shreds for me. How else can you learn, right?

Anywho, let's get down to it.

According to popular opinion, the universe has existed for about 13.7 billion years. Ever since the day it came to be, it has been expanding, and it would seem evolving as well, as hydrogen turns to helium, turns to heavier and heavier elements and creates more and more stars, which eventually explode and become planets, again producing more and more elements. Eventually, at some point, life began on this planet (the actual event we can consider irrelevant, we can be pretty sure it happened at some point, ha, ha), as a single cell organism, becoming more and more complex, right up until today.

Statistically, I think we can assume this would happen on other planets as well. Whether this is organic life, or perhaps some other form of life, I guess we can't really know (Cover THAT in an unbiased manner, you organic life forms!). That doesn't really matter either, at this point. What matters is that we can assume that they're out there.

Here's where (I think) this gets tricky. See, statistically it's damn near impossible that these aliens would be exactly as evolved as us, since we've only been around for a couple million years, and only been looking to the starts for a couple hundred. If we were to make a bell curve of all the possible times that life came to be on different planets, I'd stick us right in the middle, where we'd most likely be.

But that gets me thinking about the ends of the bell curve. Why do so many planets in the universe not have any perceivable (to us, at least) life forms? Have they already come and gone? We've been around for such a short time, how can we know if they have? What about the other end? Are they some kind of super-being, watching everything, all the time (hee hee, paranoia is great)? can they even perceive us, or are we comparable to the most basic of life forms, invisible and unimportant? After all, they'd be hundreds of millions, perhaps even billions, of years more evolved than us, wouldn't they?

Even worse, are we hundreds of millions of years ahead of, say, possible life on mars? What could that have done to the evolutionary chain there? Have we been unwittingly playing god all over the solar system, cutting out new life in the name of exploration? Can we ever know, 100%?

Like I said guys, yell, call me names, abuse my thoughts via the interwebs, I don't care. I just want to get a dialogue going on this, millions of brains being better than one and all.