On Tuesday 19 December 2023 at 01:32:13 UTC+2, MarkE wrote:
This discussion builds on a recent thread on Damer and Deamer's OoL model [1]. They propose hydrothermal fields in which molecular systems are driven far from equilibrium by cycles of hydration and dehydration, with encapsulation and combinatorial
selection in a hydrated phase.
Scenarios involving wetting/drying are not new, nor is this particular model presumed to be correct. However, I think it does highlight key issues that any model will need to address:
1. Chemical SELECTION before chemical EVOLUTION
This is an important distinction. D&D first envisage many different polymers developing independently in parallel. These are then enfolded in membranes during the hydration cycle. Some successfully contribute to membrane structural integrity, and are
therefore returned to the laminar structure in the dehydration phase. Thus, they are SELECTED by virtue of being recycled (the others are diffused and lost), but individually they are not replicating, and therefore chemical EVOLUTION is not yet occurring.
Chemical evolution prior to a functioning protocell has been postulated, e.g. a naked molecular replicator, or autocatalytic set/hypercycle of replicators. There are major problems with this, such as the ability to sustainably generate polymers of
increasing size and fidelity. Another barrier with this pathway is whatever polymers develop, they are selected for their superior replication in this context, which is essentially unrelated to the integrated functionality required when they are
subsequently enclosed in a protocell membrane. It’s like the fastest 100m sprinters being selected...for the debating team.
2. Chemical EVOLUTION
In the course of the chemical selection described above, D&D then imagine the chance coming together and integration of several different polymers to create “minimally viable sets of functional polymers” in the first protocell. Each of these
polymers is labelled with a letter as follows [2]:
S - stabilizing factors for membrane integrity
P - pore forming for controlled nutrient and waste transfer
M - metabolism, capable of catalyzing growth
F - controlled by feedback networks
R - self-replication
D - division, e.g. a primitive FtsZ protein that forms a contractile ring for cell division
The transition to “life” as they define it occurs thus: "This system triggers a polymer mechanism D that can duplicate minimally viable sets of these polymers and deliver them by division into daughter cells. If these daughter cells contain fully
functional polymer systems and are able to grow and divide again, they form the first lines of living cells."
If the average polymer length is say 50 units, that is 300 units assembled BEFORE replication and Darwinian evolution starts. The chance formation and functional interworking of that many units is a huge hurdle.
Of course, this a speculative and simplistic model, but it gives a fair representation of what must occur, regardless of the specific pathway.
3. PROTEINS are off the menu
“In summary, the above scenario steps beyond serial approaches to the origin of life sometimes characterized as “metabolism first” or “genetics first” by proposing a complex mixture in which both metabolic and genetic functions coemerge
within a cycling, lipid-encapsulated polymolecular system (Lazcano, 2010).” [2]
The problem is, long before a ribosome, how is sustained high-fidelity replication of long amino acid chains possible?
The problem is, the proteins vastly greater catalytic function than RNA.
The problem is, what polymer except RNA could satisfy D&D’s model, or any other model which seriously grapples with realistic protocell formation?
3. The OoL field has NOT addressed this (James Tour has a point, despite the shouting)
“[OoL research has] been mainly focused on individual solution chemistry experiments where they want to show polymerization over here, or they want to show metabolism over here, and Dave and I believe that it's time for the field to go from
incremental progress to substantial progress. So, these are the four points we've come up with to make substantial progress in the origin of life, and the first one is to employ something called system chemistry, having sufficient complexity so instead
of one experiment say about proteins, now you have an experiment about the encapsulation of proteins for example, and informational molecules built from nucleotides in an environment that would say be like an analog of the early Earth, build a complex
experiment. Something we're calling sufficient complexity, and all of these experiments have to move the reactions away from equilibrium.
So what? They will find some interesting polymerisation here, catalysis there and energy efficient chemical process in third place. So the result is knowledge.
If full path of abiogenesis can be composed of such pieces is of secondary value.
The naïveté of Intelligent Design is even more astounding. They "search" God in
Big Bang and Origins of Life by expressing doubt about other scientist findings.
And what do we mean by that? Well, in in your high school chemistry experiments, something starts foaming something changes color and then the experiment winds down and stops. Well, life didn't get started that way. Life got started by a continuous run-
up of complexity and building upon in a sense nature as a ratchet. So we have to figure out how to build experiments that move will move away from equilibrium…” [3]
No one knows in what way life did start. Gibberish "by a continuous run-up of complexity and building upon in a sense nature as a ratchet"? Life got started by bork-bork-bork.
4. Show me the money
“You can't sit in a laboratory just using glassware. You have to go to the field. You have to go to hot springs, you have to go to […] Iceland and come check and sit down and see what the natural environment is like, rather than being in the
ethereal world of pure reactants and things like that…” [3] @ 6:31
Where are the demonstrations of this? Where is anything like the formation of a minimally viable protocell being addressed wholistically and experimentally shown as D&D call for? And I mean much more than say Jack Szostak's limited focus [4].
Intelligent Design search God in events from billions of years ago about
what the evidence is very few and inconclusive. We can not yet tell if whole universe started with Big Bang or only part of it and we can not tell if life was
originated on Earth or elsewhere. Finding evidences how and to what level
God was involved is clearly out of question about so partially and indirectly known events.
Prediction: the naïve hopes of “life in the lab” in the next 5 years, 20 years or 50 years will fade into silence. The OoL gap will be shown to grow into a gulf over time. D&D’s work points to its magnitude.
Careful, false prophesy is several times mentioned as characteristic of
wolves in sheep clothes; IIRC both in old and new testament.
Intelligent Design is "studying" things that they clearly can't study, while the
people involved do not look like utterly stupid. Something is weird there. Is it
excuse for not to look where one can actually find? Is it to discredit religion,
to fool believers? Also they fail too noisily, they have none positive fruits. Caught on copy-pasta like "cdesign proponentists"? So awful and shameful.
God might be is within reach right now and here, but not to them.
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[1] “Excellent presentation by Bruce Damer and Dave Deamer” https://groups.google.com/g/talk.origins/c/HMw_ZoXIIOc/m/GhDNtzHcAAAJ
[2] The Hot Spring Hypothesis for an Origin of Life https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7133448/#s009title
[3] “A new model for the origin of life: A new model for the origin of life: Coupled phases and combinatorial selection in fluctuating hydrothermal pools.”
https://youtu.be/nk_R55O24t4?feature=shared [4:29]
[4] Protocells and RNA Self-Replication https://pubmed.ncbi.nlm.nih.gov/30181195/
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