So, this BBC News story caught my eye this morning: http://www.bbc.co.uk/news/science-environment-23872765
Basically there’s more evidence for the “Panspermia” theory, which says that life began elsewhere in the solar system (or even beyond it) and was brought to Earth in comets or asteroids. It’s a theory with a venerable history in both science and science fiction, and I include all those “Chariots of the Gods” style books in the latter category. It’s a fascinating idea; biological life originates out in space, we really are spacemen, aliens to this world we find ourselves on (because everything down to the smallest microbe is an immigrant).
Of course, it also makes Mars a bit boring. Why? Well, if we go there and find evidence of ancient life, and that ancient life is basically identical to us, then we’ve learned nothing. Sure, we found out we were once Martians, but so what? If Panspermia is true, especially where it suggests that life originated on comets and came to Earth, then we learn nothing about life outside our solar system. If we were once Martians then we’ve got some of the bigger moons in the outer solar system we might get lucky with, but if it turns out to be comets then we’re stuck.
You see, if we can prove that life developed independently on other worlds in our solar system, then we can probably say with certainty that it has also developed on many, many worlds out there in the galaxy and the wider universe. If, on the other hand, all the life here originated in one place, maybe it did not develop anywhere else. Maybe we are alone. We’re not going to find out until we actually have some proof from other worlds though. Let’s get out there and see, shall we?