This is the standard panspermia argument: https://en.m.wikipedia.org/wiki/Panspermia https://en.m.wikipedia.org/wiki/Panspermia I think one needs clear evidenc

This is the standard panspermia argument: https://en.m.wikipedia.org/wiki/Panspermia https://en.m.wikipedia.org/wiki/Panspermia I think one needs clear evidence of life on a comet or another planet. Otherwise it is all circumstantial evidence.