[Grue3]

Why would life be ridiculously common? It cannot appear by itself, that would be "spontaneous generation" [1], a long rejected theory. The Earth is extremely suitable for life. It could've easily supported independently evolved life-forms. Yet every living thing we know has a common ancestor, including extinct organisms. Just based on that fact, the odds are firmly stacked against other life anywhere near us. The fact that we can observe life on Earth is just a consequence of Anthropic principle [2] and says nothing about the probability of life emerging on other planets.

[1] https://en.wikipedia.org/wiki/Spontaneous_generation [2] https://en.wikipedia.org/wiki/Anthropic_principle

[rnet85]

Spontaneous generation was never a valid scientific theory. For a more accurate one look at https://en.wikipedia.org/wiki/Abiogenesis Also, the probablity of generation of organic compounds which are precursors to life is pretty high given right environment, https://en.wikipedia.org/wiki/Miller%E2%80%93Urey_experiment