I agree, but it doesn’t have to be for us to be able to make a connection. Take the example of why ATP is the universal energy currency when any of the other nucleotide triphosphates could in principle serve the same role. There is an explanation for that fact of extant life found in abiotic chemistry. Chemistry that does not occur in any cell.
The phosphorylation of the monophosphates of the other nucleosides do not occur under a very broad range of temperature, pH, mineral and metal catalysts presence, and so on, while AMP uniquely gets phosphorylated with Fe+3 as a catalyst. The phosphorylation of AMP using Fe+3 as a catalyst does not occur in cells. That isn’t how cells phosphorylate AMP.
But extant cells and the earliest stages of cells we can reconstruct, all do use ATP as their energy currency, instead of the other nucleotides. The fact that the abiotic reaction then does proceed with AMP instead of the other nucleosides explains why cells would use ATP. That is now an explanation found in an abiotic condition not found in extant cells, for why cells would use ATP instead of the other nucleotides, as the abiotic chemistry implies that is the only one that would have been available (or at the very least, the one most readily available) however and whenever these phosphorylation reactions first evolved.
That’s a massive clue right there. It’s something found in cells, the use of ATP over other similarly suitable compounds, explained by a simple abiotic reaction not found in extant cells. A fact of life now has an explanation found in abiotic chemistry.
That explains with an example, how something can be a clue that connects something about present life, to the abiotic environment, without us needing to posit the same chemistry that occurs in cells took place in the abiotic environment.
There are other clues of a similar nature, concerning what amino acids are most plausible to have been produced in abundance in abiotic settings, and which ones are most frequently used in the earliest proteins. Then there are clues about the gradual evolution of the genetic code, and the pathways of biosynthesis of the amino acids. These lines of evidence converge on a similar set of amino acids. That’s a gigantic clue about the origins of the first peptides and proteins right there. A deep connection between phylogetic inferences of early life, and the chemistry of the abiotic environment.
There are also clues about the RNA world found in extant cells. That is, there are facts about extant life best explained by the hypothesis that there was a stage in life’s early evolution where the primary genetic material and the roles of some enzymes, was made of RNA and ribozymes, respectively. Before, or at the very earliest stages of the genetic code’s evolution.
There are ways of elucidating this evidence and explaining how it is evidence, how it is predictions that were confirmed by later observations and experiments. These are also clues, if not directly to the abiotic environment, they’re clues to much simpler stages than any life that now exists. So they are clues that connect extant life, to no-longer-existing simpler life. Something that is on the pathway in increasing complexity from the abiotic environment, and towards the complexity of the last universal common ancestor. We thus have evidence that life went through such a period.
If the “origin of life” is supposed to be the explanation for how we got to cells of a complexity approaching that of prokaryotic cells, the fact that you can even given any evidence of stages of life that are nowhere near that is remarkable and therefore worth giving.
Dave could have presented that too. To pick one off a hat: the peptidyl transferase center is structurally symmetrical, originally leading some to infer that it evolved as a duplication of a single RNA molecule. This immediately gave rise to a hypothesis that there must be a single molecule of RNA which, when duplicated, can self-assemble into an active ribozyme with the structure similar to that of the peptidyl transferase center. This experiment was done. Someone made the ribosomal active site with a small 63 nucleotide RNA string that, which present in two copies, self-assembles into a ribozyme that catalyzes peptide bond formation.
It has remarkable similarity to tRNA. This is evidence once upon a time these two, today radically different things (the giant ribosomal machine and the transfer-RNA molecule), was one and the same small molecule. There was an observation, it led to a hypothesis, the hypothesis was experimentally confirmed.
Yes, and I would. The mere act of flintknapping itself isn’t a clue to the first tools any more than me being able to toss sticks at birds is a clue to the first competitive sport. Finding flint tools is.
That you can work flint into a tool is what you can say to someone who says there’s no way ancient people’s could have made tools. Then you can say, sure they could, they could have done it like this. But you can’t say that the fact you can do that is a clue to how they first started actually doing it. That’s why finding those actual flint tools is so damned important. That real actual flint tool found in some dig is, after all, considerably more forceful both logically and rhetorically, than what you can do. It means we really can say something about how ancient peoples actually lived. Sure, much else about their lives we are forced by the lack of conservation of evidence, to be inferred in terms of relative plausibility. But we can actually still say some things on the basis of direct evidence.
Not in the slightest. I haven’t said the field of abiogenesis must proceed under the burden of explaining everything that actually happened in every little detail. When it comes to the past and deep time, of course we will always be constrained by things that was destroyed by time.
What I am saying is simply mindful of what it means to say something is a clue to the origin of life. A conceptual possibility is not a clue to a murder, any more than a conceptual possibility is a clue to the origin of life.
There’s a difference between what actually happened, and what could have happened. Totally agree. But then it is all the more forceful to be able to give clues to what really did happen when and if we can. Even if there are very few of them.
A threatening text message on the victim’s phone received days our hours before the murder is a clue. Someone coming up with a story about how some person could theoretically have killed the victim isn’t a clue. It might take the form of a working hypothesis, but that hypothesis is not itself a clue.
The butler could have done it. Many others are possible. He could have, we can’t rule it out, but if we don’t have any evidence he did then the mere conceptual possibility isn’t a clue. We don’t know if he did because we lack the clues necessary to connect him to the murder in some way. And the same goes for a whole host of people we can’t rule out could also have been involved. You can do work to piece together a story about how the butler, or someone else could have done it, but until you find evidence of that, the hypothesis isn’t a clue.
But nobody is saying we need to find out how, in every detail, life actually did originate. And I would join anyone in denouncing as irrational people who demand we need to give accounts at that level of detail “otherwise it’s all just mindless faith” or whatever.
I haven’t said that and it follows from no statement of mine that anyone is under such a burden.
Nobody has to give a total account of life’s actual origin for us to be able to say, with good reasons, that we still have clues about it. That would be an absurd burden of proof. You can still provide the clues though.
At the very least we can make physical, geological, and astronomical simulations, that will be able to constrain a whole host of parameters with respect to the formation of the planet, the nature of the earliest atmosphere, it’s mineral and geological evolution, and so on. In light of whatever facts we can extract from this, we will also be able to say which among this whole host of possible chemistries are more or less plausible to have occurred.
That will likely still narrow things down to a range of models, but even such a narrowing of the scope of possibilities is a way of getting closer to what actually happened instead of merely what could have happened.
Edit: Just to add, you seem to have misunderstood me saying that these hypothetical chemistries aren’t clues to the origin of life, with saying it’s research not worth doing or that they’re not worth bringing up in response to people who say either it’s not possible or that we’re clueless. I think that’s a really deep misreading of what I wrote.