On 12/9/24 1:11 AM, 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.

Also factor in the unknown but probably large number of other earth-like planets where similar processes could occur. If things had gone a
little differently elsewhere, we might be calling a planet in a
completely different galaxy "Earth."

Also keep in mind that life has arisen on Earth somehow (I have seen it
here, after all). Abiogenesis researchers are looking for the most
plausible mechanism for an event that was known to have happened.
Difficulties with earth-based biogenesis don't negate the fact that
panspermy and magic are, to all appearances, still less likely.

--
Mark Isaak
"Wisdom begins when you discover the difference between 'That
doesn't make sense' and 'I don't understand.'" - Mary Doria Russell

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On Mon, 16 Dec 2024 10:38:13 -0800
Mark Isaak <specimenNOSPAM@curioustaxon.omy.net> wrote:

On 12/9/24 1:11 AM, 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.

Also factor in the unknown but probably large number of other earth-like planets where similar processes could occur. If things had gone a
little differently elsewhere, we might be calling a planet in a
completely different galaxy "Earth."

Also keep in mind that life has arisen on Earth somehow (I have seen it
here, after all). Abiogenesis researchers are looking for the most
plausible mechanism for an event that was known to have happened. Difficulties with earth-based biogenesis don't negate the fact that
panspermy and magic are, to all appearances, still less likely.

Not quite panspermy, but life could have started earlier in a more
favourable pond on Mars, then a chance bolide might have seeded an Earth
that was a bit more favourable later.
Alternatively, having life exist deep down shelters it from heavy
impacts and gives it a chance to "re-emerge" after a deadly wipeout.

Getting any passing god interested in the project (and staying with
it) always seems as bit harder.

--
Bah, and indeed Humbug.

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