>Anyone else out there find it improbable that life evolved from
>nothing to complex single-cells in the few hundred million years after
>the earth and mars cooled enough to support life?
Not that improbable - a few hundred million years is a very long time. Check
out the Origins of Order by Kauffman for a mathematical explaination of how
once things get complex enough you're almost bound to get something lifelike.
>Seems more likely
>to me that life evolved more leisurely elsewhere and came here.
>Anyone know where this view is analyzed in more detail? I know there
>are concerns about cosmic rays frying cells in space, but maybe they
>can repair fast, or can hide in rocks.
Panspermia is a well-known hypothesis. Cosmic rays seem lethal to any going
life, but spores could hide in rocks. I'd think that a asteroid knocked off
a planet attaining escape velocity from a solar system would be an extremely
rare event, however.
Life transfer from Earth to Mars, or vice versa, is now considered plausible.
If we can get a chemical analysis of this (possible) Martian life you can
bet this is at the top of the things we'd look for.
I hope the finding of life (well, ex-life) on Mars holds up. It really would
be one of the great discoveries of all time.