As far as I can tell the facts show that there is no plausible explanation of how life could arise by natural processes from non-life. So though it is logically possible that it could have, I think most would agree that with our present understanding there is no plausible explanation available for how it could have. Where I disagree is that it is indeterminate. I think it’s reasonable to conclude from what we do know that it couldn’t have happened.
No, what you can say is that we currently have no, not that there is no well supported explanation for how life originated.
Yeah your opinion on this matter has been made clear.
2 Likes
That’s fine by me. 
Edit: Just to clarify, I would say we currently have no plausible explanation of how life originated.
To me all this stretching for “plausibility” is just naturalism-of-the-gaps. The gaps are huge, systemic, and most of the ones we know of apply significantly to every precursor scenario that could lead to a cell. What we have now is bleak.
Franklin Harold calls Origins a “mystery”. I’m grateful for his honesty and that’s a much better word. Robert Shapiro likened origins research to a golfer who plays through a course and then assumes that natural processes could cause the ball to go through the same course, given enough time. Fascinating chemistry research (keep doing it!), but “probably” unrelated to actual origins.
Claims to plausibility are specious anyway. People claim that because we don’t know how it happened it’s still plausible. What “plausible” in this context seems to mean is “not impossible”, and in fact nobody knows that! We don’t know if it is possible until we know how it happened, so we don’t know if it is plausible. Is naturalist origins possible or plausible? We don’t know. It’s a mystery.
But I agree with @Jim – not lookin’ good.
1 Like
As far as I know, the actions of a golfer are natural processes.
OK, I’ll give you a point for a cute comeback. 
1 Like
I like Shapiro’s analogy, because the golf course is very much like a free energy surface for molecular dynamics. The probability for the ball to go through the whole course without the golfer shows that the typical free energy surface of the golf course is not amenable to spontaneous golf playing.
So people compare complex replicating systems and their environments and find that producing replicating systems can be thermodynamically favored. In a sense, it’s like having a golf course with a very big pit (thermochemical equilibrium), and smaller pits close to the big pit, and these thermodynamically favored out of equilibrium solutions have some properties (like potentially self-replication) that are life-like. It turns out UV photochemistry is especially good at knocking chemistry into these states.
There’s been theoretical work on this (1) and experimental work (2,3) and some very rudimentary attempts to join these together (4). But there’s a lot more to be done. Just because a state is thermodynamically favored doesn’t mean it is kinetically favored. It may be very unlikely to actually end up in that state simply because the barriers are too high, or the small pit is so close to the big pit that it’s very unlikely the ball ends up there. But once a mechanism or set of mechanisms is known, the kinetics can be measured and probabilities can be estimated.
Also, in this context, plausibility tends to apply only to the initial conditions of a prebiotic chemistry experiment, and it is a problematic term, but I think it means something more than ‘not impossible’ (see (5), and the last two paragraphs of (6), both of which present a frustratingly vague but much richer picture of what prebiotic plausibility is taken to mean).
As for what all this does or doesn’t have to do with the way life may have originated on Earth or elsewhere, this may be something we will have an answer to in the next 20-40 years, depending on whether we find signatures of life on extrasolar planets, or elsewhere in our own solar system.
So the exploratory chemistry is useful for solving the origins of life problem. Maybe it shows us how life started on Earth. Or maybe how life could have started. Or maybe investigations into early Earth and Mars, and lab work, will show that a particular chemical scenario or sequence simply won’t work (or won’t work over a reasonable timescale). In that case, we’ve figured out more about the chemical parameter space, and ruled out a pathway to form life. That outcome may not be as exciting, but it’s still useful.
References
(1) England, Jeremy L, 2013. Statistical physics of self-replication. The Journal of chemical physics , 139 (12), p.09B623_1.
(and other papers of his)
(2) Sutherland, J.D., 2017. Opinion: Studies on the origin of life—the end of the beginning. Nature Reviews Chemistry , 1 (2), pp.1-7. (and references within; e-mail me for a copy of this paper if you’re interested)
(3) Benner, S.A., Kim, H.J. and Biondi, E., 2019. Prebiotic Chemistry that Could Not Not Have Happened. Life , 9 (4), p.84.
Vancouver
(4) Pascal, R., Pross, A. and Sutherland, J.D., 2013. Towards an evolutionary theory of the origin of life based on kinetics and thermodynamics. Open biology , 3 (11), p.130156.
(5) Shapiro, R., 1999. Prebiotic cytosine synthesis: a critical analysis and implications for the origin of life. Proceedings of the National Academy of Sciences , 96 (8), pp.4396-4401.
(6) Orgel, L.E., 2002. Is cyanoacetylene prebiotic?. Origins of Life and Evolution of the Biosphere , 32 (3), pp.279-281. Since this isn’t open access, I’ve quoted the last two paragraphs below, feel free to e-mail and I can send you the full article.
The reasons for accepting or rejecting reagents or reactions as prebiotic are obviously complex, but a general discussion of them would be beyond the scope of this comment. In the particular case of cytosine synthesis, there is clearly no scientific reason for rejecting cyanoacetylene and accepting cyanoacetaldehyde as a prebiotic source of cytosine (or vice versa). This is largely a semantic issue, but I believe that it is a significant one, because it is important for the field of prebiotic chemistry to distinguish clearly between the discovery of new syntheses, the elucidation of their mechanisms and the proposal of scenarios that might make them relevant to the origin of life.
In conclusion, I would like to make two further points that are peripheral to the main argument. First, Miller and his coworkers have suggested, without providing any experimental evidence, that there may be an alternative prebiotic route to cyanoacetaldehyde (Nelson et al., 2001). Evidence for such a reaction would be interesting, but would not eliminate cyanoacetylene as a potentially prebiotic molecule. Second, the plausibility of all scenarios for the synthesis of cytosine from cyanoacetylene or cyanoacetaldehyde has been challenged vigorously (Shapiro, 1999).
1 Like
Nah, more like because life exists now and we know it could not have always done so, there must be some way for it to come into existence. It would be silly to claim there’s no way X can come to exist if you have X in existence, and you have evidence that there was some point of time at which it did not. This is the situation we are actually in.
In a way we already know life’s origin from non-living materials is physically possible, since life is basically a particular collection and arrangement of non-living materials, into a ting we call life. Life is made of atoms and molecules, and these can move around and recombine in chemical reactions. Chemical reactions that today occur in cells, which in turn is how those cells grow and divide into two new cells, by the conversion of non-living constituents found in their environment, into the constituents of cells (wherein their fundamental properties aren’t altered, carbon atoms in living cells still act in accordance with how we understand the physics of atoms to operate). And those same reactions can happen when removed from the cellular context. The enzymes don’t magically stop working when not located in the cytoplasm, the electrons don’t mysteriously start to refuse to move around.
There is no in principle or physical barrier to life’s emergence that would entail a contradiction to the laws of physics as we currently understand them. Hence life’s origin is known to be physically possible, the only question is what are the conditions under which this originally occurred, and how frequently do these conditions obtain in the universe. Do they happen sufficiently frequently that we might expect it to have originated more than once in the observable universe, or are we likely to be alone? We don’t know.
1 Like
Please say more. What is it we know that applies to every precursor scenario that could lead to a cell? And what are the precursor scenarios that could lead to a cell, by the way? You’ve effectively just stated that you know how the origin of cellular life would have to happen. But that would entail the mystery is solved, and that you now know the origin of cellular life.
What I see is just poor reasoning and arguments from ignorance. Ironically it’s God of the gaps that’s taking place here. The problem is yet to be solved convincingly, you can’t see how that could be done, so Godmustadunit.
1 Like
If a physical process is not physically possible, on what basis is it logically possible?
How I understand it is that logically possible simply means as an idea it can be conceived and isn’t a contradictory concept, like a married bachelor. Metaphysically possible is the next more restrictive category but not really relevant to what we’re discussing. And the next even more restrictive category is physically possible.
So to say that it’s logically possible that natural processes are responsible for ool is to say that as an idea it can be conceived and that it isn’t logically contradictory. But there would need to be a physically viable option supported by what science knows about natural processes in order for it to be physically possible. And so far, from what we currently know, I think most everyone agrees that at present no one has any physically possible explanation of how ool could have happened by natural processes.
1 Like
No, basically no-one who knows what they’re talking about would agree with that. From the standpoint of statistical physics alone, we know it is possible for life to originate in the same way we know it’s possible for all the oxygen atoms in my living room to sort into a corner. It’s merely very unlikely, but possible.
There is no point at which something crosses over from just more unlikely, to impossible.
If the universe is spatially infinite, then somewhere there’s a version of you who had to break off writing that response because all of the oxygen atoms in his living room did indeed collect in one corner. In fact, there are an infinite number of them. (A small but infinite number of whom were amused by the coincidence before dying of hypoxia.)
5 Likes
Here’s an illustration that I think makes sense of things. It’s currently physically impossible for a gasoline powered car to drive from San Francisco to New York on a gallon of gas. Can it be logically conceived? Yes. To do so doesn’t violate any of the laws of logic. So it’s logically possible. But as per our current knowledge it’s not physically possible.
Depending on the car, its engine, conditions, etc., there comes a point where the miles it can drive crosses over from physically unlikely to physically impossible. Is it plausible that a car that can drive so far could be invented in the future? Maybe. But by increasing the complexity of the kind of car to be invented there comes a point where it can be said that it’s reasonable to conclude that it would be implausible for such a car to ever be invented.
I’ve always had a thing for irony.
1 Like
Thanks but I already understood the distinction between physical and logical possibility. As I explained, if the origin of life entailed that something had to occur that was known to be physically impossible, then your argument would make sense.
But there just is no such physical fact known that prevents life arising from non-life. You’re of course welcome to start saying something more concrete about exactly which physical fact it is you think would get in the way here(instead of describing some alternative hypothetical situation of dubious relevance). What is it that would have to happen for life to originate, which there is some physical fact you know about, that would prevent OOL from occurring?
1 Like
So? What difference does that make? That sounds like a pretty flimsy excuse to ignore the actual abundance of evidence in chemistry that implicates the utter implausibility of it. If that’s the best argument against the overwhelming amount of evidence seems like it’s on pretty shaky grounds, if it has any grounds at all.
I notice you did not point out any physical fact that would make life’s origin physically impossible. I accept this tacit concession that you know of no such fact. Thank you for admitting it.
1 Like
Wow! I’m impressed at your ability to twist a response and claim it shows something it does not show in any way, shape, or form!
Here Rumraket: Response to Dr. Tour on Abiogenesis - #32 by Rumraket you assert that James Tour’s accomplishments are irrelevant and he is using arguments from ignorance. Wow again!
So why are you on this thread? Would you like to understand why people have doubts about naturalist origins?