Re: OoL – out at first base?

On 10/12/2024 8:08 am, jillery wrote:

On Mon, 9 Dec 2024 20:50:18 +1100, MarkE <me22over7@gmail.com> wrote:
 

On 9/12/2024 8:11 pm, jillery wrote:

On Mon, 9 Dec 2024 16:54:56 +1100, MarkE <me22over7@gmail.com> wrote:
>

We need prebiotic formation and supply of nucleotides for RNA world, and
other models at some stage. The scope of the problem of the supply of
these precursors is prone to underestimation.
>
Nucleotides are chemically challenging in terms of the prebiotic
synthesis and assembly of their three constituents of nitrogenous base,
sugar and phosphate group.
>
Harder again are the requirements for supply of these building blocks.
You need (eventually) all canonical bases in sufficient concentration,
purity, chirality, activation, distribution, location, etc.
>
But the greatest problem I think is this: time. How long must you
maintain the supply described above in order to assemble a
self-replicating RNA strand? And even if you managed that, how much more
time is needed before reaching a protocell capable of self-synthesising
nucleotides? One million years? One hundred million years?
>
A hypothised little warm pond with wetting/drying cycles (say) must
provide a far-from-equilibrium system...for a million years...or
hundreds of millions of years. You can’t pause the process, because any
developing polymers will fall apart and reset the clock.
>
What are the chances of that kind of geological and environmental
stability and continuity?
>
Therefore, the formation of an autonomous protocell naturalistically has
vanishingly small probability.

>
>
There were many warm little ponds, spread throughout the young Earth,
all multiplying that probability.  Try to keep that in mind.
>

>
Of course, but that doesn't solve the problem of time:
>
     10 million ponds x 10 years != 1 pond x 100 million years

  

You need to develop a self-replicating entity that also self-synthesises
nucleotides (i.e. no longer depends on environmental supply). Aka a
protocell. This requires an unbroken development process (lineage) over
millions of years, i.e. one pond, or connected ponds.
>
And this one pond continuously pumping in a supply fresh nucleotides for
MILLIONS of years.
>
No floods, droughts or interruption of supply allowed. For MILLIONS of
years.
>
Not a chance on a young Earth (or any Earth for that matter).

  Your arguments above assume unnecessary requirements.  It's not clear
what you mean by "self-synthesises".  There are no life systems that
don't depend on the environment; even autotrophs need to pull raw
materials and energy from it.  It's also not clear what you expect
your presumptive "protocell" had to do.
 My understanding is current research assumes the first
self-reproducing *systems* would have been very dependent on the
environment to provide the conditions they needed to sustain
themselves, ex. proton gradients, before they eventually evolved
more-or-less independent protocells.

Broadly, the steps would be:
1. Self-replicating polymer - environment supplies monomers
2. Non-autonomous protocell - environment supplies monomers, lipids, etc, which are used directly by the cell
3. Autonomous protocell - environment supplies food which the cell converts into monomers, lipids, etc
I'm referring to reaching step 3.

 It's unsurprising that the closer to modern life you specify your
presumptive "protocell", the less likely unguided natural processes
would create them.  Pasteur was quite right that modern life can't
generate spontaneously, with or without the aid of intelligent
designers.   So yes, the first protocells almost certainly didn't use
complex biochemical feedback systems on which modern life relies.  The
whole point is life evolved them over time, after unguided natural
processes organized the first self-reproducing *systems*.
 WRT floods and droughts and other environmental events, they would
have been part of the *systems* that eventually evolved more-or-less
independent protocells.  And yes, there are many environments on Earth
which have existed for MILLIONS of years; ex. oceans.