So, life on Mars...

[The Firebird]

It is... and it isn't.

We've identified at least 60 meteorites on Earth that probably originated on Mars.

Stuff gets around. Life finds a way.

I mean that Earth and Mars had similar chemistries that caused life to be funneled down similar trajectories from different origins. Not that life transferred from one to the other. But even that idea is quite interesting...borate is an important stabilizer of ribose, and more common on Mars than Earth. I know some people have invoked a Mars-first idea on those grounds.

 

[Reynard]

It is... and it isn't.

We've identified at least 60 meteorites on Earth that probably originated on Mars.

Stuff gets around. Life finds a way.

Right, but the important part is that if panspermia is found to be true here, we are stuck with having no idea how common it might be for life to arise independently, and therefore no additional information on how abundant it might be in the wider universe. But if we find that microbial life evolves pretty anywhere it is possible given enough time, that paints an entirely different picture.