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Comment by derekp7 | Hacker News Reader

Is it valid to take a data point of one, combined with a time element to get an estimate? For example Earth started gaining life shortly (in geological time) after it was able to sustain it. That would indicate that either life arises easily, or that it pre existed the Earth and got seeded (panspermia).

Then at the opposite end of the scale is the long time that it took for life to go multi-cellular, and for a space program to be formed by an instance of that life.

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Well, we know life on earth is at least 3.7 billion years old, but it's not much clear how much older. Since the earth is 4.5 billion years old, that means that life could have appeared after ~17% of its life span so far, which is not THAT little. Furthermore, even if life appeared as early as the earliest estimate - just a few million years after the earth formed - we have no evidence that abiogenesis continued happening after an initial event, or that it happened anywhere except an initial location.

Those two factors may mean that abiogenesis could be an extremely unlikely event that randomly happened to occur very early in the Earth's life span.

Your line of thinking is exactly what's wrong. The fact that life emerged on earth shortly after being able to sustain life says absolutely nothing about likelihood. It could be a very likely thing. Or it could be a 1 in a 10^35 miracle that happened due to an insanely low probability event involving gamma rays hitting chemical reactions in just the right way. Until we solve abiogenesis and can demonstrably evolve life from abiotic matter, or observe other planets with life on them, this is all speculation.

>That would indicate that either life arises easily

Not really. While suggestive, all it indicates is that it arose on earth easily.

not even that. Life could have been incredibly unlikely to arise on earth, but still arise when it did as freak statistical occurrence. We only have one earth to examine, and the anthropic principle severely limits any conclusions we could draw from n=1.

Yeah, happened to arise on earth quickly would probably be the better phrasing.

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