[HN Gopher] The Conundrum of Life's Origin
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The Conundrum of Life's Origin
Author : Brajeshwar
Score : 48 points
Date : 2025-01-16 15:27 UTC (7 hours ago)
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| A_D_E_P_T wrote:
| Amino acids are common enough -- glycine has been found in comets
| and, controversially, even in the interstellar medium. Other
| amino acids have also been found in comets.
|
| Comet organics, under pressure, can turn into amino acids _in
| situ_ : https://www.llnl.gov/article/36016/amino-acids-could-be-
| prod...
|
| It's also presumed that cometary ice bombardment is the source of
| Earth's surface water, as ice or water present any earlier would
| have boiled off when the planet was young and hot.
|
| It's not much of a stretch to imagine that comets brought amino
| acids, organic compounds, and minerals to Earth as they were
| bringing water ice. A lot of those aminos and organics would turn
| into tar, but some would be protected from UV radiation by that
| same tar. With a heat source, maybe some lightning strikes, a
| good location, and a lot of luck, you get RNA...
|
| What we can't yet do is assign a probability or likelihood to
| this process. But the ingredients should be common enough.
| dboreham wrote:
| Probability is believed to be quite low based on nobody having
| reproduced the process in the lab.
| A_D_E_P_T wrote:
| It's not clear what the probability is over the ~hundreds of
| millions of years that it took on Earth. Could be that, under
| the conditions and on that timescale, we're an average or
| statistically unremarkable case.
| jolt42 wrote:
| Time means more entropy, so I would think that makes the
| calculation much more problematic, no?
| snakeyjake wrote:
| Low probabilities become certainties with billions of tests
| per year over hundreds of millions of years.
| jerf wrote:
| A common belief, but manifestly false. Probabilities tend
| to combine exponentially, and that defeats our polynomial
| universe.
|
| Or, to put it another way, it does not matter how many
| times you try to roll a million fair dice and get them to
| all come up six. It doesn't matter if the entire observable
| universe does nothing but that for the entire time from the
| start of the universe to the heat death end. It will still
| never happen.
|
| Probabilities can _easily_ be "larger" than our entire
| universe considered across both space and time. It isn't
| even a particularly remarkable thing to encounter such a
| probability.
| A_D_E_P_T wrote:
| > polynomial universe
|
| That's the mistake, right there.
|
| Surely you realize that the universe could well be
| infinite -- and, to all appearances, is in any case not
| bounded in time. As such, every low probability thing
| will "at some point" occur. Thus the repugnant
| conclusion: Boltzmann Brains. But also Boltzmann planets,
| Boltzmann galaxies, and whatever else _can_ occur _will_
| occur.
| prmph wrote:
| Then "God creating things" will also inevitably occur,
| right?
| p_j_w wrote:
| It depends on the definition of God.
| Y_Y wrote:
| > every low probability thing will "at some point"
|
| This is the "ergodic hypothesis" and is not necessarily
| true.
| daveguy wrote:
| The probability of life and all the steps that lead to it
| is obviously not more infinitesimal than all potential
| actions of all the molecules in the universe over time.
| It happened on Earth and it "only" took 150-650 million
| years after water formed on the planet. We just don't
| know how much more likely it is than "so rare we are
| lucky to be the only ones."
| snakeyjake wrote:
| >you try to roll a million fair dice and get them to all
| come up six.
|
| That is not a low probability event; that is an
| impossibility.
|
| I think the problem here is that you think I am a digital
| electronic computer. I am not.
|
| I am a human being.
|
| I do not now, have never, and will never care about the
| technically possible I only care about the actually
| possible.
|
| As a human, I know that six to the power of one million
| is impossible. Not to mention that rolling one million
| dice is absurd.
|
| But as a human I also know that the chemical reaction
| needed to spark life isn't a six to the power of one
| million proposition.
|
| I don't know what it is but it ain't that because it's
| been done, at least once.
|
| edit: It's not absurd, rolling one million dice.
|
| The heaviest verifiable weight ever lifted by a human
| being is 2422.18kg.
|
| A 4mm die is 0.4g. Conceivably a contraption could be
| built by which a human could "roll" several million dice
| using the strength of their entire body.
|
| Now I kinda want that to happen.
| tsimionescu wrote:
| > As a human, I know that six to the power of one million
| is impossible.
|
| This is plain wrong. If you roll a million dice, anything
| that comes up has the exact same probability. We think
| all 6 is special because it holds some meaning to us, but
| it is exactly as likely as any other result. So any
| result has a probability of 6^1M to happen. And yet, one
| of those 6^1M configurations will happen with probability
| 1.
| snakeyjake wrote:
| You are mistaken. I don't think one million sixes is any
| less likely than any random combination. I know that the
| odds of all possibilities are the same. That's why
| gambling disgusts me and lotteries hold no fascination
| with me.
|
| I also know that it is impossible.
|
| If you disagree, show some proof. Not "a proof". Proof.
|
| I live in the real, not theoretical world.
|
| Create a video showing one million dice rolls that have
| all hit six, and I will accept that it is not impossible
| to roll a die one million times and have every roll hit
| six.
|
| No numbers. No computer programs. No math. Dice.
|
| Mother. Fucking. Dice. Cubes covered in pips.
|
| Real, physical, standard layman's definition dice rolled
| in the real, physical, actual world.
|
| Show me! Please!
|
| Until then? S'ay imposseebluh.
| jolt42 wrote:
| For a gambler, yes, but for a biological system? Stuff
| falls apart, it's like any progress continually gets wiped.
| soco wrote:
| But boiling off would have still kept that water in the
| atmosphere right?
| HPsquared wrote:
| Not if it's hot enough that the water molecules reach escape
| velocity in the exosphere! (As happens with helium today,
| helium atoms being lighter move faster at a given temperature
| than water molecules)
| adastra22 wrote:
| Been a while since I interacted with this science, but I think
| the assumption about the magma ocean "boiling off" the water
| was an early idea that doesn't hold up? The mantle holds an
| impressive amount of water dissolved inside it, as it turns
| out.
| adrian_b wrote:
| About a half of the amino acids used in proteins, i.e. ten of
| them, can form easily in abiotic conditions and they are
| widespread in some celestial bodies.
|
| They are easily distinguished from terrestrial contaminants,
| because they are a mixture of left-handed and right-handed
| isomers.
|
| When analyzing the genetic code in order to determine which
| amino acids have already been used in the earlier versions of
| the genetic code and which have been added more recently, the
| same simpler amino acids that are easy to synthesize even in
| the absence of life are also those that appear to have been the
| only amino acids used earlier.
|
| The article contains the phrase "Given the fact that the
| current scenario is that life on Earth started with RNA".
|
| This is a fact that it is too often repeated like if it were
| true, when in reality one of the few things that can be said
| with certainty about the origin of life is that it has not
| started with RNA.
|
| What must be true is only that RNA had existed a very long time
| before DNA and DNA has been an innovation that has been the
| result of a long evolution of already existing life forms, long
| before the last ancestor of all living beings that still exist
| now on Earth.
|
| On the other hand, proteins, or more correctly said peptides,
| must have existed before any RNA. Moreover, ATP must have
| existed long before any RNA.
|
| RNA has two main functions based on its information-storage
| property: the replication of RNA using a template of RNA (which
| was the single form of nucleic acid replication before the
| existence of DNA) and the synthesis of proteins using RNA as a
| template.
|
| Both processes require complex molecular machines, so it is
| impossible for both of them to have appeared simultaneously.
| One process must have appeared before the other and there can
| be no doubt that the replication of RNA must have appeared
| before the synthesis of proteins.
|
| Had synthesis of proteins appeared first, it would have been
| instantly lost at the death of the host living being, because
| the RNA able to be used as a template for proteins could not
| have been replicated, therefore it could not have been
| transmitted to descendants.
|
| So in the beginning RNA must have been only a molecule with the
| ability of self replication. All its other functions have
| evolved in living beings where abundant RNA existed, being
| produced by self replication.
|
| The RNA replication process requires energy and monomers, in
| the form of ATP together with the other 3 phosphorylated
| nucleotides. Therefore all 4 nucleotides and their
| phosphorylated forms like ATP must have existed before RNA.
|
| ATP must have been used long before RNA, like today, as a means
| of extracting water from organic molecules, causing the
| condensations of monomers like amino acids into polymers like
| peptides.
|
| The chemical reactions in the early living forms were certainly
| regulated much less well than in the present living beings, so
| many secondary undesirable reactions must have happened
| concurrently with the useful chemical reactions.
|
| So the existence of abundant ATP and other phosphorylated
| nucleotides must have had as a consequence the initially
| undesirable polymerization and co-polymerization of the
| nucleotides, forming random RNA molecules, until by chance a
| self-replicating RNA molecule was produced.
|
| Because the first self-replicating RNA molecule did not perform
| any useful function for the host life form, but it diverted
| useful nucleotides from its metabolism, this first self-
| replicating RNA molecule must be considered as the first virus.
| Only much later, after these early viruses have evolved the
| ability to synthesize proteins, some of them must have become
| integrated with their hosts, becoming their genome.
|
| The catalytic functions that are now performed mostly by
| proteins, i.e. amino acid polymers that are synthesized using
| an RNA template, must have been performed earlier by peptides,
| i.e. typically shorter amino acid polymers that are synthesized
| without the use of RNA templates.
|
| Even today, all living beings contain many non-ribosomal
| peptides, which are made without RNA, using processes that are
| much less understood than those that involve nucleic acids.
|
| The difference between a living being that would be able to
| make only non-ribosomal peptides and one that makes proteins
| using RNA templates is pretty much the same difference as
| between a CPU with hard-wired control and a CPU with micro-
| programmed control, with the same advantages and disadvantages.
|
| Life forms able to reproduce themselves must have existed
| before the appearance of the nucleic acids, but they must have
| been incapable of significant evolution, because any random
| change in the structure of the molecules that composed them
| would have been very likely to result in a defective organism
| that would have died without descendants. This is similar with
| a hard-wired control, where small random changes in the
| circuits are unlikely to result in a functional device.
|
| On the other hand, once the structure of the enzymes was
| written in molecules of nucleic acids, the random copying
| errors could result in structures very different from the
| original structures, which could not have been obtained by
| gradual changes in the original structures without passing
| through non functional structures that could not have been
| inherited.
|
| So the use of molecules that can store the structural
| information of a living being has enabled the evolution towards
| much more complex life forms, but it cannot have had any role
| in the apparition of the first life forms, because the
| replication of any such molecule requires energy that can be
| provided only by an already existing life form.
| highfrequency wrote:
| Awesome post and thanks for writing this out - probably the
| most insightful piece I've read on plausible origin of life
| through pre-RNA autocatalytic peptides. Would you be willing
| to share a contact email / online profile? (could edit
| afterward to delete if you are worried about spam from
| crawlers)
| adrian_b wrote:
| a dot bocaniciu at computer dot org
| exe34 wrote:
| sorry if I missed it, but it sounds like you've just pushed
| the mystery one step back but still ended up with the same
| mystery - where did the original Titan species come from? is
| there any evidence for their existence other than your belief
| that an RNA replicator would have needed a host cell? would
| this host cell have been built out of lipid bilayers? what
| would its inside mechanisms be made of - if not protein or
| RNA?
| nathan_compton wrote:
| Ultimately science always terminates in so-called brute
| facts. I'm not sure it always makes sense to call these
| mysteries. In the end, some things appear to simply be
| without any sort of causal or even logical explanation. I
| try not to get too worked up about it.
|
| On the other hand, one has to keep kicking over rocks to
| see what is underneath or life would get boring.
| f1shy wrote:
| Thanks. People like you make HN an enjoyable place.
| rstuart4133 wrote:
| Thank you so much. Awesome post.
| A_D_E_P_T wrote:
| https://archive.ph/585kK
| Ericson2314 wrote:
| I never like the emphasis on genetics and information in a lot of
| origin of life stuff. IMO it is too extensional; what is needed
| is good _intensional_ reasoning.
|
| At the heart of chemical life is
| https://en.wikipedia.org/wiki/Autocatalysis, this is a great
| intensional definition of the reproductive side. That just leaves
| the evolutionary side.
|
| What do "genetics" achieve for reproduction. From the
| autocatalysis point of view, they create a _family_ of "nearby"
| autocatalytic sets: because different nucleic acid sequences
| reproduce in much the same way, the conditions needed to
| propagate one should also propogate another. This in turn makes
| _safer mutations_ and....Lamarckian inheritance! If you, a
| microrganism get a good mutation which makes you fit, and then
| you split, you pass that mutation on.
|
| Genetics are sufficient for the above properties, but are they
| necessary? Probably not! We can probably find other things which
| have such a "dense/smooth mutation space" with fewer local maxima
| traps. Perhaps it is fine to say such things definitionally
| encode information, but IMO information still comes second,
| philosophically.
| ljsprague wrote:
| >it has to be able to reproduce and evolve by natural selection
|
| Not sure why something has to be able to evolve by natural
| selection in order to be considered alive.
| pinoy420 wrote:
| I mean. It was God (whatever that means to you).
| jolt42 wrote:
| Oh, you mean "Programmer #1" using the original assembly
| language?
| m3kw9 wrote:
| Just think about it, a conscious being deciding what a life
| should be. There is certainly a bias towards how we were made.
| standardly wrote:
| I have a layman theory on protocell organization. It can't
| explain replication, but hear me out. So one of the most likely
| candidate locations for abiogenesis, purportedly, are
| hydrothermal vents. Now, consider Cymatics
| (https://en.wikipedia.org/wiki/Cymatics). Maybe you can draw the
| same conclusion I did.
|
| Wave formations are a source of order amidst the chaos (pressure
| waves in this case). This may be testable, even. If it did hold
| any truth, then the popular, common mythos' of "the Word" or
| "speaking things into existence", or creation via music etc...
| maybe was more intuitive than we realized :)
| standardly wrote:
| https://www.youtube.com/watch?v=OWLtTP07FCw
|
| Well, my comment is going to end up hidden. I guess this just
| isn't that interesting, and I assume the video I am linking
| here will be seen as meaningless with no possible historical
| bearing on physics or chemistry.
|
| Is there a good reason this is not being considered? Like,
| these abiogensis articles never say anything new, and have no
| interesting propositions. They say it's a mystery, then propose
| a vague implausibility that can only be explained by another
| mystery. Like, I would appreciate at least some creative
| thinking here.
| thangalin wrote:
| My book dives into the timeline of life's origins as well as
| summarizing how we know what we know about roughly when life
| started:
|
| https://impacts.to/downloads/lowres/impacts.pdf#page=10
|
| The little orange dot represents where the events happened along
| the timeline between the start of the universe and recent times.
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