Novel Idea on the Origin of Life

[Torbjorn_L]

As I understand what I have read about biogenesis

(e.g., Vital Dust: Life as a Cosmic Imperative (1996) ISBN 0-465-09045-1)​

there are bottlenecks in the process. I have also read about several suggestions that our relatively over-sized moon may have played an important role in getting past such a bottleneck. It seem reasonable that if the moon played such a role, the fact that such a moon exists would be a bit of luck.

My take:

There are two main theories of life emergence, soup and vent. The soup theory is preferred by many chemists & biochemists as it looks into chemical pathways to replicating protocells, the vent theory is preferred by many geologists & biologists as it looks into phylogenetic pathways from geology to biology.

The main problem with soup theories is to drive some key steps. Therefore they tend to end up with many pot systems (i.e. different reactors for different reactions) and freeze/thaw or wet/dry cycles to drive steps that are non-spontaneous. That is why they can see the Moon, or Mars, as important.

Vent theories have the same problem, but they tend to stick with the observed reactors. E.g. for Orgel's theoretical problem with squandering in side reactions of non-enzymatic reaction chains, Keller et al showed that gluconeogenesis/glycolysis and the phosphate pentose pathway are as efficient without enzymes in the Hadean ocean. And for RNA replication it has been shown that vents doing PCR for replication are the only known reactors that naturally lengthen strands.

Instead you the problem to do it all without enzymes and other cycling than thermal. Since vents can produce the substrate pyruvate from H2 and CO2 with self-deposited greigite under Hadean conditions in the lab, and Keller et al just showed that there is a natural pH/FeII control of the pathways so that the inner vent would produce pentose and the outer a glucose buffer, we are halfway to RNA and an energy (polyphosphate) metabolism. (The requisite amino acids have glycolysis as starting pathway IIRC.)

Two reactions to get the purine base pairs are still outstanding... And of course no one has yet showed natural PCR akin to Keller's natural metabolisms. So make that 3 reaction steps out of some 30+ steps, depending on how you count them. The cells could be inorganic pores at the start.

TL;DR: With this rate we have a geological reactor making RNA cells quicker than the next blue moon.

The current fossil record indicates that the vent theory is likelier I find, because life may have emerged as soon as the ocean became habitable over 4.3 Ga [billion years ago]. There is a putative 4.1+ Ga fossil, and TimeTree phylogenetics prefer the first known split (bacteria/archaea) to happen 4.2+ Ga. Soup theory seems too complicated and fragile for all that. Admittedly I can't quantify the conclusion in any way.

Let me see what I can find. I know I've read about it again just recently in a book by Lee Smolin.
https://www.amazon.com/dp/0544245598/?tag=pfamazon01-20

He was discussing this concept during a section covering physical systems that tend to behave in ways that are anti-thermodynamic (with decreasing entropy)... such as gravitationally bound systems.

Yes, please do not say that! Thermodynamics in GR is complex since you have spacetime volumes that changes. However gravitationally bound systems on an approximately flat background can be completely understood to radiate away heat to the universe as they bind tighter, same as all systems with potential wells behave. [ http://math.ucr.edu/home/baez/entropy.html ]

 

[Feeble Wonk]

Yes, please do not say that! Thermodynamics in GR is complex since you have spacetime volumes that changes. However gravitationally bound systems on an approximately flat background can be completely understood to radiate away heat to the universe as they bind tighter, same as all systems with potential wells behave. [ http://math.ucr.edu/home/baez/entropy.html ]

Absolutely agreed. The "decrease" in entropy was specifically limited to the isolated subsystem of increasing order. But, definitely, entropy is correspondingly increased over the entire system as a whole.

 

[Feeble Wonk]

Hi @Feeble Wonk:
The bottle neck I was thinking of takes place before cells formed. I do not recall that de Duve discussed in detail how the process of RNA evolution took place.

For whatever it's worth, de Duve did address this issue in his earlier Vital Dust publication (1995), but he left it as an unsolved mystery... perhaps the key unsolved mystery of abiogenesis.

 

[Buzz Bloom]

And for RNA replication it has been shown that vents doing PCR for replication are the only known reactors that naturally lengthen strands.

Hi @Torbjorn_L:

I didn't know what PCR was, so I found the following:
From https://en.wikipedia.org/wiki/Polymerase_chain_reaction

The method relies on thermal cycling, consisting of cycles of repeated heating and cooling of the reaction for DNA melting and enzymatic replication of the DNA.
​

Can you cite any references about the PCR mechanism being used to demonstrate one or more of:
(1) RNA replication (rather than DNA)
(2) the use of RNA "enzymes" (rather than protein enzymes)
(3) evidence of PCR functiong in an open vent-like environment (rather than in test-tubes)?

Regards,
Buzz