Describing the odds as "slight" isn't really meaningful. Let's say the odds of intelligent life occurring are one in a million. That's pretty unlikely. But if there are ten million earths out there in the universe, it becomes quite likely that intelligent life occurs on one or more of them. In fact, it would be unlikely that no intelligent life arose anywhere.

Conversely, if there are only 100,000 potential earths, then there is a fair chance that none of them will contain intelligent life (apart from ours, of course).

Unfortunately, we cannot yet obtain accurate figures of a) the odds for or against life evolving, or b) the number of potential life-bearing planets.

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Spike
:)