| > it happened on Earth almost as soon as the oceans formed But that might have been the final item in a long list of requirements. Maybe life form quickly (on a planetary-scale of quickness) once they are met, but who knows how long that list is. TBH, I think people fixate on "life" because of some star-trekkian fantasy about aliens, and specifically, other space-faring aliens. There are lots of interesting life-forms on earth that are ignored. We have a lot yet to learn about chemistry, let alone the biochemistry of bacteria, algae, mould. Dolphins and octopi have yet to build boats, let alone spaceships (arguably the monkeys are ahead on this game). TBH, I'm more interested in what kind of interesting materials and phenomena might exist on other planets. As for life, I think its more interesting to think about what kind of alien environments we can seed with life (and what would form) rather than the moon-shot of actually finding life we are exited about. Also keep in mind: life or not, it might be more likely we find something else interesting or dangerous. e.g. some kind of adaptable self-replicating enzyme, but made of something more durable than protein (and reproducing in the environmental). Consider the rubber-eating contaminant in https://en.wikipedia.org/wiki/The_Andromeda_Strain |