I believe there's lots of life out there and a very rare bit of it will be what we roughly think of as intelligent.
Similar conditions and processes that gave rise to life on earth could happen elsewhere on a multitude of worlds - and likely have. Even extra terrestrial life elsewhere in our own solar system seems like a reasonable possibility to me, for example on Europa. We have vent ecosystems on planet earth that get their energy from heat and chemicals vented from our planet rather than the sun. Similar ecosystems could exist under the surface of otherwise inhospitable worlds.
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Originally Posted by Xurtio
We've seen a LOT of planets out there and only one has contained life (Earth).
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We haven't seen a lot of planets. We've detected a lot of planets. Generally, they are detected by watching stars. When a planet passes between our telescope and the star we are looking at, there is a change in the luminosity of that star. The bigger the planet, the bigger the change. Hence, this method is best for finding really big planets and not small, rocky, earth-like ones. And when a planet is detected this way, it doesn't mean we've gotten a look at it and could possibly see if it contains trees or cities.
Quote:
Originally Posted by Xurtio
Certainly our own existence is proof that its possible, but it's also an improbable event.
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Winning the lottery is an improbable event, but there are still plenty of lottery winners. Even if the lottery was a million times harder to win, there would still be winners - even if they'd be a few years apart.
Life elsewhere in the universe has
a lot of chances.
Imagine that we are the product of one lineage of life that stretches back all the way to some origin of life (if hard to pinpoint). If that origin hadn't happened or life had completely died out some millions of years later, we wouldn't have been here. But maybe life would have redeveloped in a new lineage or maybe the 30th attempt would have been the successful one. This planet could have animals on it or be inhabited only by unicellular organisms or whatever. It might not be humans, but it would likely be something.
I think a likely problem with intelligent life is that it probably tends to eradicate itself by using up and destroying resources and then crashing. Maybe intelligent civilizations only tend to last a short while.