[ExI] Chemical Origins of Life (was Re: Panbiogenesis)

[Eugen Leitl]

On Sat, Feb 04, 2012 at 09:20:23PM -0700, Kelly Anderson wrote:

> > It is completely impossible to tell how typical or atypical our
> > origin and history are without having access to at least one,
> > preferably multiple samples which originated outside of common causal
> > origin. The solar system is probably insufficient, unless we have clear
> > evidence of multiple independant origins within this very
> > system (improbable due to crosscontamination).
> 
> If the life were sufficiently different, say not DNA or RNA based,

Yes, this is what I meant by "outside of common causal
origin". Though elemental abundancies would still have an 
impact, albeit a much smaller one. There's sufficient
variation out there so that would only have a small effect,
less than an order of magnitude probably.

> then it would probably be sufficient to rule out cross contamination.

We haven't found a single instance of a shadow biosphere yet on
this planet, so probably any crosscontamination would wipe out
the weaker biosphere. As a corollary, anything we'll find on Europa
or elsewhere will be our close relative, biochemically.
 
> >> In other words, some kind or another of procaryotes could in be pretty
> >> frequent in the universe, while  eucaryotes may just not be "required".
> >>
> >> This, irrespective of how much procaryotes species can be diverse and
> >> interesting and evolutionary successful, would be a quite boring and bleak
> >> scenario from our own perspective... :-/
> >
> > Right, we're looking for someone we can relate to, or at least
> > look upward to.
> 
> Good, you read that the same way I did... :-)

Even if nobody is out there this is still plenty of real estate
ready for taking -- especially, if there's no prior owner. Extremophiles
don't really count as such, though they may beget such gigayears downstream.