In any given environment, the chemicals with the best conditions to synthesize will be more prevalent, possibly using up molecules that could have been used in other chemicals given other circumstances. [To draw a parallel, this would be similar to the best adapted animals being more populous, and using up resources that less fit animals could use. I realize that being the most populous isn’t the basis of evolution if you depend on having a small populous that lives on obscure resources, since you’re still reproducing, but I don’t think it causes any major issues in the general premise.]
Over time, these prevalent chemicals will tend to, stochastically, bond with other molecules and atoms, becoming more advanced.
Aaaand… eventually one randomly becomes advanced enough that it’s the first prokaryote, at which point classical evolution takes over.
I assume that since this is a fairly obvious line of thinking somebody has refuted exactly what’s fallacious about it, so what precisely stops the theory of evolution from being applicable to the origin of life given an “evolutionary” approach to chemistry? I assume it probably stems from a rather fundamental misunderstanding of how chemistry in complex systems works (chemistry is not exactly my strong science), that or I have no grasp over the theory of evolution.
Evolution specifically refers to the change in the frequency of alleles over successive generations within populations. Evolution does not attempt to explain the origin of life and has no application to it. Abiogenesis is not evolution. It’s pre-evolutionary.
I have tried to explain this concept to others on multiple occasions, without success. To me, it’s an extremely obvious point, and should be somewhere citable in the literature. Unfortunately the word “evolution” is pretty loaded, as evidenced by Dio’s rather dense response.
I’m of agreement with the OP. I think (perhaps cynically, but nonetheless, I really do think) the reason people speak otherwise is just because it’s “politically” advantageous, so to speak, to draw this dividing line at the origin of cellular structures and RNA/DNA or whatever; it provides room for those people who feel a need for "God-did-it"ery at some point in the process to at least accept the mechanics of evolution as having been in play from thereon out.
Yeah, yeah, there’s a seismic shift involved and the history of the evolution of life is much better understood from that point on out as well, etc., etc., but c’mon; like the OP, it seems clear to me that the same abstract ideas of natural selection, mutation, etc., are just as applicable at the pre-cellular level as they are at the cellular level.
Anyway, I suppose the thing to do would be to read about the Miller-Urey experiment and such things.
No, because evolution requires procreation. Individuals don’t evolve. A cell that mutates is not evolution if it doesn’t produce more cells that are also mutated.
Oh, and that experiment required a ton of human intervention for selection to take place. And, even then, the results had over half the chemicals not used in biological life (the wrong isomers, as well as the wrong amino acids). And it is predicated on an incorrect view of the primitive atmosphere, specifically tailored to the experiment. It’s a nice little concept, but it really hasn’t explained anything.
Yes, the two concepts are superficially similar, but they are also so different and so less understood that I believe they deserve a different name. Calling it evolution gives Creationists something to use to discredit it.
I think that gets at the root of my misunderstanding. The chemicals are growing and changing, but they’re not really splitting and reproducing, which undermines some of the fundamentals.
I still think some of the broad concepts have clear applicability, but now I can see why it’s not really called “evolution” at that point.
The core idea of evolution – the same idea that could apply equally well to the evolution of alien species that may not have the same technical mode of reproduction as do terrestrial ones, that is, natural selection – applies perfectly well to chemical reactions, as all chemicals have enzymatic characteristics that allow themselves to catalyze self-reproduction to varying degrees. But even putting that fact aside, the fact that even, say, H2O exists is due to a form of natural selection – less stable molecules “die off” and more stable molecular configurations “survive.” The mode of reproduction is simply more abstract – the “parents” are “dying” unstable configurations, such as H and OH, and the mechanism of hereditary variability is combinatorics.
Evolution is probably not a useful word on its own. Many things evolve. The conversation on this thread evolves, relationships evolve, even ideas evolve. Evolution of a species is a very different matter. Clearly that already presupposes that some species exit, and then gets technical. Part of the issue is that “evolution” as applied to life, and used as a noun, (i.e. as in the thread title) is not the same word, and has a specific set of connotations, basically becoming shorthand for “natural selection applied to the evolution of biological species.”
There is no reason why natural selection cannot cover the evolution of processes. But the process is not directly described as a species, and is not subject to the rigours thus imposed.
On the biogenesis front, it has been a long time, by I recollect that in the all time classic The Blind Watchmater, Dawkins did actually spend some time describing a hypothetical set of processes that when subject to natural selection might account for evolution towards a proto-living entity. When you might decide that enough complexity had evolved to anoint the entity with the notions of both living and species, that is probably a very long blur. At that point evolution takes on its role as a noun.
Evolution requires (imperfect) replication, not necessarily procreation. If there’s a soupy mix of chemicals with processes that are cyclic/self-replicating, then evolution can occur there, regardless of whether we consider anything in there to be alive.
Imperfect replication, plus selection equals evolution. The details of the system in which this occurs are largely arbitrary.
The reason evolution doesn’t explain origins in the context of evolution/creationism debate (the only place I’ve ever seen the question arise) is that it stops being a question of general process, and becomes a question about a specific event in prehistory - it’s a matter of detail about a specific sequence of events - it’s ‘what?’ as opposed to ‘how’ or ‘why?’
Paring abiogensis with evolution is a little odd. You’re only making evolution more complex than it needs to be. A good theory should have a certain level of parsimony, simplicity, etc. Imagine if the theory of gravity was rolled up with the big bang. It doesn’t make much sense to do that.
Abiogenesis itself is more of a catchall for a lot of theories. Its kinda like pre-Darwinian evolution where people accepted that animals changed over time, but weren’t sure exactly how or how to test it.
Going back to the OP (and Warning: major hand-waving ahead) …
I agree strongly with Francis Vaughan’s pointers on terminology.
Chemistry in general tends to drive towards a tightly bound low energy configuration. Which is why we don’t find free O or OH floating around for long.
To show that “evolution” (loosely used) applies to pre-biological chemistry, we’d need to show a natural tendency for some chemicals to get more complex & higher energy over time. And to be able to retain that configuration for non-trivial timespans. I don’t think modern science has done that, and I certainly don’t think the OP’s mere assumption that this is true is warranted.
IOW, given enough of the chemicals which life makes now, DNA, ATP, the amino acids, etc., it’s fairly easy to imagine enough instances of these things getting together in proximity to add up to the first cell or cell-like thing.
The challenge is positing a mechanism for getting from a bunch of carbon & oxygen & hydrogen to having a bunch of ATP floating around.
FTR I’m a firm believer in original biogenesis being a natural process, with no religious inputs. Nevertheless, I think there’s a big gap in the OP’s thinking of applying “evolution” (loosely used) or even imperfect replication to driving complex chemistry “uphill” against the normal direction of entropy.
Evolution is more about the concept that random mutations that change inherited characteristics will tend to cause a species to change until it is best adapted to its current environment…
Chemical “evolution” is more about the statistics of random pairing and the ability of some (organic) chemicals to have a catalyst effect in producing similar compounds. Given that Miller’s experiment produced significant building blocks of life in a short time in a tiny volume, the odds that something significant would develop in a volume the size of the earth biosphere over hundreds of millions of years… is not surprising. Amino acids are relatively stable compounds, so it’s not a surprise if the next step after their formation is the random pairing that could produce in sequence RNA, DNA, virus-like compounds and then DNA inside protective membranes; since the chif benefit of RNA and DNA is their ability to produce themselves and other useful compounds much like catalysts.
Whether this should be characterized as “evolution” is a whole separate debate over terminology.
Interesting, I read somewhere where the scientist who inherited Miller’s sealed experiments used modern equipment to re-analyze the results, and found that in fact the number and complexity of the organic compounds were much grater than Miller could measure with 1950’s technology.
I don’t think so, because biological evolution has no particular direction, other than that which is expedient.
In order to apply the term ‘evolution’ to pre-biological chemistry, we only need posit that there existed a variety of candidate precursory chemicals/processes, and that something selected the ones that were most prolific, or most durable, or otherwise most persistent. I think both of these criteria are pretty obviously true. It’s far more likely that there would be a variety of different chemical compounds proliferating, than a uniform substance, and it’s exceptionally likely that those compounds would have different properties affecting their persistence.
That’s evolution, without life - it doesn’t have to be heading anywhere, even particularly in the direction of becoming life.
You are describing evolution though. Sorry to bang on about this, but if you have a bunch of different stuff, and the stuff that does something so as to cause more of the same kind stuff to come about, thus prevailing over the stuff that doesn’t quite make the grade, or is otherwise less suited to persistence - that’s evolution.
Evolution is an observed phenomenon. It cannot explain anything, it just is.
The theory of selection by survival in large populations of reproducing members of a species resulting in speciation over long periods of time is an explanation for the observed phenomenon. It is only a small part of the explanation, and the entire explanation is very long, very complex, and still only partially understood.
Abiogenesis is a separate observed phenomenon. We observe that there is life. Given the likely state of the universe at its beginings, life as we observe it seem sufficiently unlikely to be dismissed as a possibilty at that time. So, at some time since then, life began. One may speculate that this too resulted from prior iterated separate phenomena. That would be speculation. One could then propose theories on the mechanism of such a process, if they can be formulated. Such theories would have to be testable, repeatable, and the evidence predicted by the theory found for that theory to have signifigance for the theory of selection and speciation. I know of no cases where that process has been completed.
The theory of evolution does not explain the origin of life because that’s not what Darwin was trying to explain. The title of his seminal work is The Origin of Species, not The Origin of Life.
Similarly, Isaac Newton’s Principia Mathematica addresses the laws of motion, celestial mechanics, and that other thing I always forget, but is silent on molecular structure.