>>14431161People underestimate how unlikely abiogenesis is.
You need random organic compounds to randomly coalesce into lipids, carbohydrates, and amino acids. These then have to randomly coalesce into membrane layers, cellulose, and proteins, respectively. These then have to randomly coalesce into simple cells while at the same time (and in the same relative area) some other biopolymers are randomly coalescing into RNA. Only then do you start the process of biological evolution as we understand it. And all this on a planet with water, a habitable temperature cycle, orbiting a star with just enough UV radiation to spur random mutations. The Great Filter is the emergence of life itself. You'd be lucky to see it twice in the same galaxy.
If we get out into space and it's Star Trek, with bipedal humanoids with slightly different foreheads on every other planet, I'd assume the galaxy had been life-seeded.
