The big problem I have with the RNA world idea, and its experimental implementation, is that it runs in a soup that doesn't seem plausible.
RNA gets made from pure, energy-rich molecules that themselves are quite complex. This soup of pure monomers isn't something that just arises naturally in the absence of life. Prebiotic chemistry produces a random soup of a wide variety of chemical species, with the abundance of each declining exponentially in its size and complexity.
You see this issue all the time in origin of life claims. For example, that recent result of "all the bases of RNA and DNA were found on this asteroid by the Japanese" tended to slide over the fact that they were there at extremely low levels, mixed with huge numbers of other non-biological organic molecules.
Trying to replicate RNA in a mix of random crap will just give you polymers of crap, if it gave you anything at all.
OoL needs an idea that will work in a soup of junk, not in massively artificial pure soup on a lab bench.
Robert Shapiro's 1986 book "Origins" had a rather snarky takedown of that kind of OoL research.
The research does something like this. You run an experiment and show some chemicals are present in low concentration. You say "ah ha, we've shown one step". Those chemicals are now taken off the shelf in high concentration and used in the next experiment, which makes slightly more complex chemicals in low concentration. Repeat this multiple times until done.
Lampooning this, the fictional OoL researcher in the book also demonstrates that monkeys can type out "To be or not to be, that is the question" on a typewriter. He arranges the typewriter with an automatic right margin and lets them type away until he gets a line starting with "T". First letter demonstrated! Now he rereun the experiment, but now with paper the "T" in the first column and margins set to the second column. Repeat this with subsequent letters until the entire sentence is produced. Of course, the monkeys didn't type the sentence, the researcher did.
Getting around the exponential complexity barrier is the whole goddamn point, it's not something to just wave away with a "we don't know" comment.
IMO some fundamentally new idea is needed for OoL.
> Of course, the monkeys didn't type the sentence, the researcher did.
But the researcher is performing the selection process for the purposes of the experiment, to speed things up. Evolution functions via natural selection. That's what makes it different from the pure random chance processes.
Well, what do you expect. We don't have direct evidence, apart from the fact that we evolved from single cells to a man typing response to a clueless comment which wants to see everything laid out nicely and every part covered 100% because thats how it should be.
You cannot point out exact steps how we evolved till now yet here we are. "We don't know" is a perfectly fine answer even if it somehow triggers you. Universe is not arranged around such folks, universe doesn't care about some tantrums, universe just is, in ways we still don't fully understand and thats fine.
It seems obvious that if replication of elementary particles appears that everything else will be an emerging property given enough time. And if you look at atoms and math there're definite parallels that once atoms can interconnect stronger than everything else (considering the 3d world) and something like Penrose's tiles where you get repeating interconnecting structures that more higher level structures would be possible. And with energy connected to the particles momentum and Heisenberg's uncertainty principle you get fluctuations in the structures that allow for both new structures and enforcing of the construction rules. You also have clear levels between forces that work on different levels that create boundaries to the structures. 3 spacial dimensions give additional directions of interactions between structures. And voila, given conditions, there's a place for emerging properties. Whether it was RNA who knows. It does seem that the search becomes way murkier toward going into the actual mechanism but the ingredients seem to be in place
Is there a reason why the alternative idea of closed autocatalytic sets from Stuart Kauffman doesn't get nearly as much attention or discussion as the RNA origin hypothesis?
Ever since I first learned about it, it seems to me a much more likely origin of life hypothesis, as it doesn't require something to catalyze itself, which causes inevitable problems with mutation causing loss of catalytic efficiency.
Also, it is not incompatible with RNA being one of the early building blocks. It just doesn't require RNA to be where everything started.
“ Holliger’s team looked for catalytic activity in small RNAs (between 20 and 40 nucleotides in length), allowing for small changes in length in each cycle of mutation. They found a 45-nucleotide molecule that they christened QT45 (“quite tiny”) that could seize another RNA strand and copy it. “In principle it can copy any sequence,” Holliger said.”
I don't think you can say this with certainty. It is assumed that life and evolution go hand-in-hand from the beginning but it is not proven to be the case.
It could be proven if there was a record found of something that predated the currently known fossilized bits from really long ago that would give a hint about how life at that stage was put together. This is highly unlikely to happen.
> There’s scarcely any corner of Earth in which life hasn’t gained a foothold[..]
About that, not that long ago I was entertaining the idea of what environments can be completely devoid of life. I was thinking about examples like a volcano Cauldron, a nuclear reactor or the insides of a particle accelerator.
When I read about self-replicating RNA I always think about the equivalent in the protein world, the prions. One can make many parallelisms with these scary proteins, responsible of the Creutzfeldt-Jakob disease.
Of course, the are too many limitations for evolving into some more complex, but they can self-replicate and they can infect other organisms. If we could give them an oceanic soup of PrPC and enough time, who knows?
Prion "replication" seems rather different from self-replicating RNA.
Isn't the building block that a prion requires to create a copy of itself essentially a chemically almost-identical protein that is just folded differently?
How about an alternative analogy of the prion folding pattern spreading through chemically-similar molecules like a meme through a population of similarly conditioned brains?
Yes, I agree and that is why I mentioned that there are limitations. It really depends how one interprets "replication" and that the ingredients needed to self-propagate are to be considered valid building blocks for the beginning of life or not. As far as I know, RNA would use nucleotides and prions similar already existing complex proteins. It seems that the RNA hypothesis is more plausible. However, I just found out that there's some that actually believe that life started with prions and not RNA since proteins are more stable. Although
I like your analogy memes and prions need an already existing condition and then twist them into something else. If we are allowed to enter the philosophical domain, it's like the devil's work twisting the mind of the righteous or the Sith turning the force-sensitive beings :-)
The hardest part of the transition from prebiotic chemistry (assembling the building blocks) to an 'RNA World' is doing so in a way that can support RNA copying. As others have shown the chance of finding one replicator is low - so you need supporting RNA copying chemistry at a pretty substantial level to help that happen.
This is where the hard part of the field is currently: finding chemistry that can support accurate RNA copying that is also both sufficiently high yielding and also compatible with these reactions being inside protocells (fatty acids for example). An RNA genome only really has value when it can be selfish and keep any innovations it makes to itself inside a protocell!
I work in Origins Research - if you have questions please ask and ill try to answer with the current opinions of the field!
For a long time, since I learned about how evolution works at the gene level, I’ve been bedazzled by sharks. Here is a configuration of genes which has reached such a sweet spot in the eyes of evolution that it has cruised mostly uncharged (modulo the shrinking due to change in oxygen composition) for hundreds of millions of years. Then I learned about the code of RNA (credit to Deutsch I think in his treatment of evolution in Fabric or maybe it was Beginning, I don’t recall) and my mind was blown! The actual knowledge encoded in the RNA sequence—†not the physical stuff; but the precise coded sequence—required for replication is actually quite ubiquitous across species and unchanged on timescales vastly larger than I had previously fathomed, mountains look like sand castles and sharks are brand new in the eyes of the code of RNA. This is only an analogy; but it felt like how Unix works: RNA is like the tiny kernel which has spread everywhere due to being tiny and good enough to solve the problem and therefore difficult to replace. Anyways, this is only a day dream since I’m not really in the weeds; but I wonder if you can correct any of my misconceptions. Like: RNA is like code for DNA replication, is it sort of like low-level machinery for life? Has the precise RNA code survived a really long time and it’s sort of like an old operating system which just keeps humming in the background? And it is older than sharks right? Any other cool stuff to recommend pursuing for someone like me who really loves evolution; but is just a layperson?
†one note about my em dashes: I am a real person who thinks evolution AND em dashes are cool and for a total aside: it’s such a bummer people think I’m a bot just because I like tinkering w/ f* punctuation marks.
> actual knowledge encoded in the RNA sequence—†not the physical stuff; but the precise coded sequence—required for replication is actually quite ubiquitous across species and unchanged on timescales
There is a chance that before 'LUCA' there were many dead ends and we ended up on the lucky branch by definition, and we don't actually know much about what happened before then so there is some possibility that what you are seeing there is the single largest example of 'survivorship bias'.
Does the current SOTA believe that it's most likely that life originated on Earth? I know there are some theories that at least one of the critical building blocks was delivered via asteroid or other extra-terrestrial process.
But that doesn't answer the origin of life. Even if it came from outer space, it must have an origin somewhere. Currently, the science is focusing on the possibility that life originated here because the problem does not become easier to solve by considering another planet's environment.
I think the biggest unresolved question isn't whether RNA can replicate itself, but how you get from occasional replication to a self-sustaining system
Most mutations are negative dead-ends, not unlikely DNA now where most pregnancies spontaneously abort due to errors. But life has many, many chances — especially at the molecular scale. So what’s the actual problem?
Similarly, if you have a soup of 10-15 nucleotide sequences, what are the odds actually that they’d link into larger segments?
Let’s suppose that density is a million times lower than blood, so you have one picogram per gram of water. There are 10^24 grams of water on Earth’s surface and 10 base pairs weighs 10^-20 grams, giving us approximately 10^32 segments of that length.
Feel free to play with my numbers, but I’m supposed to believe that with ~10^30 pieces, we can’t have ten of them form the right sequence?
A combinatorial explosion. To have mutations you need to have replication first. If a smallest viable self-replicator is, say, 100 nucleotides long, and there's not many other such replicators of the same length, the improbability of its spontaneous formation (~4^-100) dwarfs any amount of material available on Earth.
The researchers have found QT45 replicator. But it replicates other RNA strands, that is it needs another replicator nearby to replicate itself, which brings the probability down to 4^-90 range.
And it's not clear from the article whether QT45 is a viable replicator. That is whether it is stable enough and replicates other RNA strands correctly enough to sustain exponential growth instead of petering out due to filling its surroundings with broken copies that don't perform replication before decaying itself.
I doubt a replicator came out of thin air. It seems more likely, at least to me, that we started with constructors, that created primitive sequences.
Imagine you have molecules that can form spontaneously, like gliders in Conway's Game of Life. You may have several different molecules that are capable of helping to create one another -- an autocatalytic set.
Eventually this could result in more complex chains, and eventually a self replicating molecule can arise.
Imagine slamming a bunch of gliders together to make a machine that replicates more gliders. It's possible! Not likely, but there are so many variables that can influence the environment substantially. It's not like there was a giant homogeneous soup. Parts from over here and over there would form differently and when they meet, amazing things can happen.
In the Game of Life, this spontaneous event is extremely unlikely, astronomically unlikely.
Unlike Game of Life, the real world has a few advantages that improve performance. For one, it's less fragile. Bonds are much stronger and collisions don't cause everything to break. Another advantage is that bonds are attractive: molecules can rotate and turn to snap together strongly. Gliders just explode violently. And finally, the real world is very dense. We're talking trillions of molecules mixing around millions of times per second per microdroplet. Compound that with a few hundred million years... it certainly doesn't feel as surprising as you might expect.
If there were a highly advanced alien race watching earth over a long period of time, it might be interesting, but not unexpected, that suddenly an Eiffel tower springs forth from the surface of the planet, erected by intelligent organisms.
The simple combinatorial explosion criticism feels reductive to me. It's exceedingly unlikely that a single "self-replicating RNA molecule" formed independently by chance and then propagated.
Let's say that you have some RNA soup with some ribozymes some of which weakly encourage some reaction involving other RNA molecules. The occurrence of a cycle of reinforcing reactions might be sufficient to build a crude evolutionary ratchet.
In fact the "cycle of reactions" perspective feels a bit more robust to me since it allows for the proto-replication process to take place over a longer period of time and over larger areas.
Yeah, it's more probable a priory, but it still can be false. For example, such reaction chains might not lead to a sufficiently probable increase in complexity.
Core wars (1984) strongly favored short replicators, so at least in some possible universes complexity growth is not a given.
Life didn't have to start on Earth. It could have started on any one of an unbounded number of worlds. It's only in retrospect that this world seems special.
What's the probability of spontaneous formation across an infinite universe?
In an infinite universe even events with probability 0 can happen[1], but it's hard to find this explanation satisfactory. Any hypothesis that raises probability of abiogenesis to make it likely to happen at least in the observable universe looks more satisfactory than "but it could have happened anyway in an infinite universe despite being totally improbable."
If you mean panspermia specifically in respect to earth it's a lot more bounded in space and time to the parts that were close enough to interact with earth, but if not then yes there is probably anything that can be represented by atoms out there somewhere or other.
Your numbers are fine - but RNA is fragile; making one copy of something really rare will not be able to do anything as it will not last long enough to meaningfully contribute.
Interestingly we now are thinking about ways to use mutations in other ways, youve spent a lot of energy making these polymers, so it would be a shame to waste that right? We think that they can be used to assemble larger functional pieces as mutations are mostly deterministic meaning you'll get the same kinds of errors - so why not put them to use!
Early on that may have been a feature though, isn't it?
What strikes me as the most interesting thing about life is that almost immediately (on geological time scales) after Earth had developed an environment where life in theory could exist it came to be. That suggests strongly that the mechanism to do so was relatively simple. Then again, the Earth was a vast laboratory and it only has to happen once.
I also don't understand. Adding billions of years to your numbers probably makes it an even better point.
"Life's first molecule." Take your favorite quantum field theory and consider how it draws a line between a molecule and not a molecule. Consider how it draws a line between life or not. That'd be cool. Consider that it doesn't give a shit who did what first.
suddenly, as we enter the realm of nanotechnology ourselves, the speculative possibility of intelligent design becomes more plausible . Who knows how, what, or where life had started, but we might be the second version.
this kind of speculation only moves the needle forward, the main question remains: even if life on earth is part of an intelligent design experiment, how does life in this intelligent entity world began in a first place?
42 comments:
The big problem I have with the RNA world idea, and its experimental implementation, is that it runs in a soup that doesn't seem plausible.
RNA gets made from pure, energy-rich molecules that themselves are quite complex. This soup of pure monomers isn't something that just arises naturally in the absence of life. Prebiotic chemistry produces a random soup of a wide variety of chemical species, with the abundance of each declining exponentially in its size and complexity.
You see this issue all the time in origin of life claims. For example, that recent result of "all the bases of RNA and DNA were found on this asteroid by the Japanese" tended to slide over the fact that they were there at extremely low levels, mixed with huge numbers of other non-biological organic molecules.
Trying to replicate RNA in a mix of random crap will just give you polymers of crap, if it gave you anything at all.
OoL needs an idea that will work in a soup of junk, not in massively artificial pure soup on a lab bench.
Well we don’t know what is and what’s not possible on a planetary scale (i.e. trillions of interactions daily). At least not yet.
Robert Shapiro's 1986 book "Origins" had a rather snarky takedown of that kind of OoL research.
The research does something like this. You run an experiment and show some chemicals are present in low concentration. You say "ah ha, we've shown one step". Those chemicals are now taken off the shelf in high concentration and used in the next experiment, which makes slightly more complex chemicals in low concentration. Repeat this multiple times until done.
Lampooning this, the fictional OoL researcher in the book also demonstrates that monkeys can type out "To be or not to be, that is the question" on a typewriter. He arranges the typewriter with an automatic right margin and lets them type away until he gets a line starting with "T". First letter demonstrated! Now he rereun the experiment, but now with paper the "T" in the first column and margins set to the second column. Repeat this with subsequent letters until the entire sentence is produced. Of course, the monkeys didn't type the sentence, the researcher did.
Getting around the exponential complexity barrier is the whole goddamn point, it's not something to just wave away with a "we don't know" comment.
IMO some fundamentally new idea is needed for OoL.
> Of course, the monkeys didn't type the sentence, the researcher did.
But the researcher is performing the selection process for the purposes of the experiment, to speed things up. Evolution functions via natural selection. That's what makes it different from the pure random chance processes.
Well, what do you expect. We don't have direct evidence, apart from the fact that we evolved from single cells to a man typing response to a clueless comment which wants to see everything laid out nicely and every part covered 100% because thats how it should be.
You cannot point out exact steps how we evolved till now yet here we are. "We don't know" is a perfectly fine answer even if it somehow triggers you. Universe is not arranged around such folks, universe doesn't care about some tantrums, universe just is, in ways we still don't fully understand and thats fine.
It seems obvious that if replication of elementary particles appears that everything else will be an emerging property given enough time. And if you look at atoms and math there're definite parallels that once atoms can interconnect stronger than everything else (considering the 3d world) and something like Penrose's tiles where you get repeating interconnecting structures that more higher level structures would be possible. And with energy connected to the particles momentum and Heisenberg's uncertainty principle you get fluctuations in the structures that allow for both new structures and enforcing of the construction rules. You also have clear levels between forces that work on different levels that create boundaries to the structures. 3 spacial dimensions give additional directions of interactions between structures. And voila, given conditions, there's a place for emerging properties. Whether it was RNA who knows. It does seem that the search becomes way murkier toward going into the actual mechanism but the ingredients seem to be in place
Lee Cronin's "assembly theory" tries to formalize this idea: https://en.wikipedia.org/wiki/Assembly_theory
Is there a reason why the alternative idea of closed autocatalytic sets from Stuart Kauffman doesn't get nearly as much attention or discussion as the RNA origin hypothesis?
Ever since I first learned about it, it seems to me a much more likely origin of life hypothesis, as it doesn't require something to catalyze itself, which causes inevitable problems with mutation causing loss of catalytic efficiency.
Also, it is not incompatible with RNA being one of the early building blocks. It just doesn't require RNA to be where everything started.
“ Holliger’s team looked for catalytic activity in small RNAs (between 20 and 40 nucleotides in length), allowing for small changes in length in each cycle of mutation. They found a 45-nucleotide molecule that they christened QT45 (“quite tiny”) that could seize another RNA strand and copy it. “In principle it can copy any sequence,” Holliger said.”
You need evolution to have life. Why is mutation a deal-breaker?
> You need evolution to have life.
I don't think you can say this with certainty. It is assumed that life and evolution go hand-in-hand from the beginning but it is not proven to be the case.
How exactly can it be proven? Even if we create life from scratch and see it evolve, it won't be a definitive proof
It could be proven if there was a record found of something that predated the currently known fossilized bits from really long ago that would give a hint about how life at that stage was put together. This is highly unlikely to happen.
> There’s scarcely any corner of Earth in which life hasn’t gained a foothold[..]
About that, not that long ago I was entertaining the idea of what environments can be completely devoid of life. I was thinking about examples like a volcano Cauldron, a nuclear reactor or the insides of a particle accelerator.
If you expand the bounds beyond Earth there are a lot of environments completely devoid of life…
I assume the caldera is hotter than what this little dude can take https://en.wikipedia.org/wiki/Methanopyrus
When I read about self-replicating RNA I always think about the equivalent in the protein world, the prions. One can make many parallelisms with these scary proteins, responsible of the Creutzfeldt-Jakob disease.
Of course, the are too many limitations for evolving into some more complex, but they can self-replicate and they can infect other organisms. If we could give them an oceanic soup of PrPC and enough time, who knows?
Prion "replication" seems rather different from self-replicating RNA.
Isn't the building block that a prion requires to create a copy of itself essentially a chemically almost-identical protein that is just folded differently?
How about an alternative analogy of the prion folding pattern spreading through chemically-similar molecules like a meme through a population of similarly conditioned brains?
Yes, I agree and that is why I mentioned that there are limitations. It really depends how one interprets "replication" and that the ingredients needed to self-propagate are to be considered valid building blocks for the beginning of life or not. As far as I know, RNA would use nucleotides and prions similar already existing complex proteins. It seems that the RNA hypothesis is more plausible. However, I just found out that there's some that actually believe that life started with prions and not RNA since proteins are more stable. Although
https://www.youtube.com/watch?v=K0K-pMPFzGY
I like your analogy memes and prions need an already existing condition and then twist them into something else. If we are allowed to enter the philosophical domain, it's like the devil's work twisting the mind of the righteous or the Sith turning the force-sensitive beings :-)
Sorry, I went off the rails.
The hardest part of the transition from prebiotic chemistry (assembling the building blocks) to an 'RNA World' is doing so in a way that can support RNA copying. As others have shown the chance of finding one replicator is low - so you need supporting RNA copying chemistry at a pretty substantial level to help that happen.
This is where the hard part of the field is currently: finding chemistry that can support accurate RNA copying that is also both sufficiently high yielding and also compatible with these reactions being inside protocells (fatty acids for example). An RNA genome only really has value when it can be selfish and keep any innovations it makes to itself inside a protocell!
I work in Origins Research - if you have questions please ask and ill try to answer with the current opinions of the field!
For a long time, since I learned about how evolution works at the gene level, I’ve been bedazzled by sharks. Here is a configuration of genes which has reached such a sweet spot in the eyes of evolution that it has cruised mostly uncharged (modulo the shrinking due to change in oxygen composition) for hundreds of millions of years. Then I learned about the code of RNA (credit to Deutsch I think in his treatment of evolution in Fabric or maybe it was Beginning, I don’t recall) and my mind was blown! The actual knowledge encoded in the RNA sequence—†not the physical stuff; but the precise coded sequence—required for replication is actually quite ubiquitous across species and unchanged on timescales vastly larger than I had previously fathomed, mountains look like sand castles and sharks are brand new in the eyes of the code of RNA. This is only an analogy; but it felt like how Unix works: RNA is like the tiny kernel which has spread everywhere due to being tiny and good enough to solve the problem and therefore difficult to replace. Anyways, this is only a day dream since I’m not really in the weeds; but I wonder if you can correct any of my misconceptions. Like: RNA is like code for DNA replication, is it sort of like low-level machinery for life? Has the precise RNA code survived a really long time and it’s sort of like an old operating system which just keeps humming in the background? And it is older than sharks right? Any other cool stuff to recommend pursuing for someone like me who really loves evolution; but is just a layperson?
†one note about my em dashes: I am a real person who thinks evolution AND em dashes are cool and for a total aside: it’s such a bummer people think I’m a bot just because I like tinkering w/ f* punctuation marks.
> actual knowledge encoded in the RNA sequence—†not the physical stuff; but the precise coded sequence—required for replication is actually quite ubiquitous across species and unchanged on timescales
Good source that develops on this?
I'm not 100% but I think they are referring to the fact that ribosomes are highly conserved across species.[0]
https://en.wikipedia.org/wiki/Ribosomal_RNA#Sequence_conserv...
There is a chance that before 'LUCA' there were many dead ends and we ended up on the lucky branch by definition, and we don't actually know much about what happened before then so there is some possibility that what you are seeing there is the single largest example of 'survivorship bias'.
Dinosaurs were the same.
Does the current SOTA believe that it's most likely that life originated on Earth? I know there are some theories that at least one of the critical building blocks was delivered via asteroid or other extra-terrestrial process.
But that doesn't answer the origin of life. Even if it came from outer space, it must have an origin somewhere. Currently, the science is focusing on the possibility that life originated here because the problem does not become easier to solve by considering another planet's environment.
My favourite (unlikely one) - https://lweb.cfa.harvard.edu/~loeb/habitable.pdf (not saying Avi Loeb isn't cuckoo).
I think the biggest unresolved question isn't whether RNA can replicate itself, but how you get from occasional replication to a self-sustaining system
I don’t understand the objections:
Most mutations are negative dead-ends, not unlikely DNA now where most pregnancies spontaneously abort due to errors. But life has many, many chances — especially at the molecular scale. So what’s the actual problem?
Similarly, if you have a soup of 10-15 nucleotide sequences, what are the odds actually that they’d link into larger segments?
Let’s suppose that density is a million times lower than blood, so you have one picogram per gram of water. There are 10^24 grams of water on Earth’s surface and 10 base pairs weighs 10^-20 grams, giving us approximately 10^32 segments of that length.
Feel free to play with my numbers, but I’m supposed to believe that with ~10^30 pieces, we can’t have ten of them form the right sequence?
> what’s the actual problem?
A combinatorial explosion. To have mutations you need to have replication first. If a smallest viable self-replicator is, say, 100 nucleotides long, and there's not many other such replicators of the same length, the improbability of its spontaneous formation (~4^-100) dwarfs any amount of material available on Earth.
The researchers have found QT45 replicator. But it replicates other RNA strands, that is it needs another replicator nearby to replicate itself, which brings the probability down to 4^-90 range.
And it's not clear from the article whether QT45 is a viable replicator. That is whether it is stable enough and replicates other RNA strands correctly enough to sustain exponential growth instead of petering out due to filling its surroundings with broken copies that don't perform replication before decaying itself.
I doubt a replicator came out of thin air. It seems more likely, at least to me, that we started with constructors, that created primitive sequences.
Imagine you have molecules that can form spontaneously, like gliders in Conway's Game of Life. You may have several different molecules that are capable of helping to create one another -- an autocatalytic set.
Eventually this could result in more complex chains, and eventually a self replicating molecule can arise.
Imagine slamming a bunch of gliders together to make a machine that replicates more gliders. It's possible! Not likely, but there are so many variables that can influence the environment substantially. It's not like there was a giant homogeneous soup. Parts from over here and over there would form differently and when they meet, amazing things can happen.
In the Game of Life, this spontaneous event is extremely unlikely, astronomically unlikely.
Unlike Game of Life, the real world has a few advantages that improve performance. For one, it's less fragile. Bonds are much stronger and collisions don't cause everything to break. Another advantage is that bonds are attractive: molecules can rotate and turn to snap together strongly. Gliders just explode violently. And finally, the real world is very dense. We're talking trillions of molecules mixing around millions of times per second per microdroplet. Compound that with a few hundred million years... it certainly doesn't feel as surprising as you might expect.
If there were a highly advanced alien race watching earth over a long period of time, it might be interesting, but not unexpected, that suddenly an Eiffel tower springs forth from the surface of the planet, erected by intelligent organisms.
The simple combinatorial explosion criticism feels reductive to me. It's exceedingly unlikely that a single "self-replicating RNA molecule" formed independently by chance and then propagated.
Let's say that you have some RNA soup with some ribozymes some of which weakly encourage some reaction involving other RNA molecules. The occurrence of a cycle of reinforcing reactions might be sufficient to build a crude evolutionary ratchet.
In fact the "cycle of reactions" perspective feels a bit more robust to me since it allows for the proto-replication process to take place over a longer period of time and over larger areas.
Yeah, it's more probable a priory, but it still can be false. For example, such reaction chains might not lead to a sufficiently probable increase in complexity.
Core wars (1984) strongly favored short replicators, so at least in some possible universes complexity growth is not a given.
Life didn't have to start on Earth. It could have started on any one of an unbounded number of worlds. It's only in retrospect that this world seems special.
What's the probability of spontaneous formation across an infinite universe?
In an infinite universe even events with probability 0 can happen[1], but it's hard to find this explanation satisfactory. Any hypothesis that raises probability of abiogenesis to make it likely to happen at least in the observable universe looks more satisfactory than "but it could have happened anyway in an infinite universe despite being totally improbable."
[1]https://en.wikipedia.org/wiki/Almost_surely
If you mean panspermia specifically in respect to earth it's a lot more bounded in space and time to the parts that were close enough to interact with earth, but if not then yes there is probably anything that can be represented by atoms out there somewhere or other.
Your numbers are fine - but RNA is fragile; making one copy of something really rare will not be able to do anything as it will not last long enough to meaningfully contribute.
Interestingly we now are thinking about ways to use mutations in other ways, youve spent a lot of energy making these polymers, so it would be a shame to waste that right? We think that they can be used to assemble larger functional pieces as mutations are mostly deterministic meaning you'll get the same kinds of errors - so why not put them to use!
> but RNA is fragile
Early on that may have been a feature though, isn't it?
What strikes me as the most interesting thing about life is that almost immediately (on geological time scales) after Earth had developed an environment where life in theory could exist it came to be. That suggests strongly that the mechanism to do so was relatively simple. Then again, the Earth was a vast laboratory and it only has to happen once.
aside: you have the most interesting job!
I also don't understand. Adding billions of years to your numbers probably makes it an even better point.
"Life's first molecule." Take your favorite quantum field theory and consider how it draws a line between a molecule and not a molecule. Consider how it draws a line between life or not. That'd be cool. Consider that it doesn't give a shit who did what first.
"given any word, there's no such thing"
suddenly, as we enter the realm of nanotechnology ourselves, the speculative possibility of intelligent design becomes more plausible . Who knows how, what, or where life had started, but we might be the second version.
this kind of speculation only moves the needle forward, the main question remains: even if life on earth is part of an intelligent design experiment, how does life in this intelligent entity world began in a first place?