Ok so in the paper that I gave you Tour speaks a little about Lipid membranes, but I think that another paper of his actually show an area of agreement between Tour and Lane (who I’ve read by the way). In the paper linked below Tour explains:
Blockquote The lipids are just the beginning. Protein–lipid complexes are the required passive transport sites and active pumps for the passage of ions and molecules through bilayer membranes, often with high specificity
Now in his book the Vital Question Lane explained that a sealed liposome would not be able to maintain its proton gradient w/o some mechanism to selectively allow ions to pass through the cell membrane so he suggested that they evolved a sodium proton antiporter which is what modern cells use. So actually Lane, Miller and Tour agree that enzymes are needed to power free living cells. Lane simply assumes the antiporter had evolved by the time the protocells where free from the vent, which he assumes where more like the vents in his laboratory that uses all of the advanced chemistry synthesis a scientist of Lane’s caliper can create.
Meanwhile as the paper linked below explains pH gradients that are central to his hypothesis may not even form in nature as explained in the paper linked below:
So I’m not ignoring Lane, I just don’t find his hypothesis convincing for many reasons.
Technically antiporters aren’t enzymes(at least they don’t chemically alter their substrates), though some transport proteins can be. Regardless, I agree with that too. But that’s different from claiming life has to begin with free living cells. I think you should spend some time trying to understand the difference between those two claims.
Also, nobody thinks protocells had modern phospholipid membranes that are impermeable to ions and small molecules.
That is his hypothesis he’s actively working to test.
That statement is literally gibberish. Nick Lane makes no assumption that “the vent was more like the vents in his laboratory”. Rather, he’s using technology to try to re-create in a laboratory setting, how a natural environment of a particular type would behave. It’s a simulation under conditions that are conducive to experiment because they permit measurements that aren’t possible to do in natural settings.
Dude you should be able to understand this most basic point.
Some researchers are simply trying to create natural environments in the laboratory in as simple a way as possible
In the real world the water bubbling out of a hydrothermal vent is hot because it comes up from deep in the Earth’s crust where it has been heated, ultimately, by radioactivity in the Earth’s interior. It would not make sense to demand that researchers re-create the entire core and mantle of the planet just to acquire a source of heat to make the water in their system hot.
No, they use a Bunsen burner. No, there weren’t Bunsen burners on the early Earth, but the water was still hot. The relevant factor is that the water was hot, not that it was made hot by flame or by radioactive decay. So can they use a Bunsen burner to heat the water? Yes, they can. Is that cheating? No, not in any imaginable world.
And Nick Lane has responded to it at length. Still irrelevant to James Tour who seems to be completely unaware of his work, and everyone else who works on metabolism first, or other forms of chemical evolution scenarios.
Also I must repeat what I wrote in different posts in this very same thread 2 years ago:
This whole Henry Morris routine you’re playing by picking opinions, quotes, and arguments from different opposing camps in this field to try give the impression that all proposals are wrong(the arguments from camp A disprove camp B, and the arguments of camp B disprove camp A), is a well-worn and misleading creationist trick.
Arch-charlatan Henry Morris wrote an entire book (“That their words may be used against them”) consisting of nothing but such cherry-picked quotes, lifted out of their surrounding and historical context, from opposing camps on a whole host of hotly contested topics in geology and physics, to astronomy and biology.
Taking the quotes at face value one might derive the impression that all of the findings of modern science concerning natural history, from the early history of the universe, to the formation of stars and planets, including Earth, is all wrong. That was of course the purpose for which he went and collected these quotes, being a young Earth creationist his delusional viewpoint basically required adopting the view that all of science is wrong.
Merely pointing to one or both sides in a lot of different debates for a selection of quotations arguing that opposing views are unlikely given assumption X does not constitute meaningful discussion.
At any given moment in science there is some advancing frontier of research, where certain topics are hotly contested, and in those moments you can find statements by people on different sides arguing that the views of their opposition are somehow all unlikely, implausible, or impossible. Yet such debates usually eventually settle, and one side comes out being right and the other side wrong. You can go pick quotes from the period when the mechanism of oxidative phosphorylation was unknown and a subject of hot contest, to “prove” that (taking the arguments from both camps) life must be impossible, because apparently there’s no way any mechanism of oxidative phosphorylation could possibly occur and suffice to power life. But one side won that debate eventually, and the other side lost, and we now know ATP is generated by chemiosmosis.
You can find lots of papers arguing that “the other guy’s scenario for the RNA world is wrong and here’s why”, it’s just that it’s all based on innumerable assumptions that have yet to be settled(some argue there was no dry land at all, not even volcanoes of any appreciable size, which would basically rule out all versions that involve evaporation and wet-dry cycles, leaving only submarine hydrothermal vents among presently conceived settings for life’s emergence), and are likely to remain unknowns for quite a while, because there’s scant little evidence for what the earliest periods in Earth’s history was really like.
Your “see this paper argues against X the matter is now settled” MO is becoming rather stale.
If you were even marginally gracious, you would admit that I was correct in meeting your arrogant challenge and pointing out that Tour arrogantly and completely ignored metabolism-first hypotheses in the article you so arrogantly touted (apparently without ever bothering with evidence). Then you had the audacity to hypocritically accuse ME of not basing my position on evidence.
Why would you do that? And why would you capitalize “lipid”?
So what? There’s zero acknowledgment of metabolism-first hypotheses in there. It’s literally claiming that lipids and proteins are required BEFORE metabolism!
Does the plain meaning of the word “first” really escape you?
No, they don’t. And notice that you, the one who so arrogantly accused me of avoiding evidence, is trying to spin hearsay from three people without EVER citing a speck of evidence.
Why is that?
It’s a review. As in someone’s opinion, not the evidence. Who’s avoiding evidence?
You definitely were. Your arrogant challenge to me was to point out what Tour was ignoring, remember? You clearly lack the basic graciousness to concede that I met the challenge easily.
You’re also digging deeper, because if you understood Lane and still touted Tour’s paper as comprehensive, when you already knew that it completely ignored the metabolism-first hypotheses of Lane et al., you were being cynically dishonest…
Geremy seems to have confused himself for James Tour. We point out an entire section of the field is missing from Tour’s anti-science rants and Geremy responds that he himself isn’t ignoring anything. One might surmise Geremy is actually Tour himself advertising his claptrap.
I would agree with you that different perspectives may at times be of interest. However, in this discussion, Miller argued against the well-established fact that hydrophobic interactions in the cell are entropy-driven. In light of this, I would view Miller’s pronouncements with at least as much skepticism as does @Mercer (and, I suspect, others here).
Tour doesn’t have claptrap he has reasonable observations that you wish to dismiss as irrelevant for reasons that I will not speculate about. When Tour carefully explains why simple lipid vesicles such as those touted by Lane and other metabolism first theorists aren’t capable of creating the gradients seen in biological cell membranes genetically expressed without proteins being embedded in their membranes is he really ignoring metabolism first hypotheses? I don’t see how that’s the case. If you would like him to spend more time explaining why he doesn’t think metabolism first is plausible maybe you should ask him. Here’s a video with him explaining some of the problems with metabolism first hypotheses:
… then he is blathering about irrelevancies as no-one, including Nick Lane, thinks or even proposes that vesicles with simple fatty acid membranes are.
In Nick Lane’s proposal the ion gradient is maintained across a mineral membrane, not an organic one. That’s the whole point of the alkaline hydrothermal vent hypothesis, that the disequilibrium between hot H2 rich hydrothermal fluids coming coming out of a hydrothermal vent, and the cold CO2 rich acidic ocean waters surrounding it, results in a pH (H+, proton gradient) across the mineral membrane. And that it is this gradient that initially powers biosynthesis.
Here’s their first proof of principle, that a mineral barrier can act as a membrane that sustains a pH gradient, that in turn powers the synthesis of a simple organic molecule:
I found no such discussion anywhere in that video. It’s just complaints about exercises in lipid synthesis as making assumptions Tour doesn’t agree with. Irrelevant.
Sorry for the long delay in responding to your points.
It IS quite the leap back
Well, no; it’s not such a huge difference, that’s England’s point. Entropy can drive self-organization, provided there is sufficient energy available.
It is, however, a bit of a “Spherical Cow” argument, because it doesn’t shed much light on what actually happened. A lot of OoL research is looking at what sorts of chemical energy would be available and pathways to self-sustaining chemical reactions.
That was a very interesting paper. but I don’t think that it is relevant to the origins of life since it used concentrations of nickel that don’t exist in probiotic nature to achieve its results. Perhaps you think that Tour’s constantly talk about concentrations of reagents is meaningless blather, but it is essential to understanding whether or not the results of this experiment could have actually occurred in an early earth or if it could only happen in a laboratory or cell.
So we both know that nickel is a trace element in the earth’s crust and mantle, but that it uses by some microbes for CO2 fixation. Here’s what one paper says about that:
Blockquote
On Earth, Fe represents 5.5% and Ni only traces of its crust… Anaerobic methanogenic archaea use four of the nine known Ni-containing enzymes to reduce CO2 and evolve CH4 as a waste product.[18](javascript:;),[19](javascript: These enzymes are [NiFe]-hydrogenase…
Now after I read your paper, I went to the supplemental materials link and at section 2.5 read that the researchers used a 98.0 pure Nickel Chloride salt and similarly pure iron salt for their experiments. Why would there be 98% pure trace metal salt, just chance near an alkaline vent on a continuous basis making formate on a prebiotic earth for no reason at all?
So when Tour constantly says that these OOL experiments aren’t prebiotically relevant it’s not claptrap, he’s just being honest. If was prebiotically relevant when the researchers eliminated the unrealistic abundance of trace metals it still would have worked. Here’s what the paper that you gave me says happened instead:
Blockquote
Without Ni in the ocean precipitation fluid, the yield dropped below our limit of quantification, suggesting that Ni is a crucial part of the precipitate for the reduction mechanism operating here.
So as I mentioned earlier and this paper demonstrates, just because chemical reactions can occur in biology and the laboratory doesn’t mean that they could occur on an early earth without guidance or biology. I think that is what Tour is explaining and the better I understand the science the stronger I understand his perfectly reasonable position to be.
So should I assume that 98% pure nickel salts continuously swirling in the ocean near alkaline vents happened? Because if it didn’t then the best evidence for this alkaline vent hypothesis suggests it really didn’t happen due to blind naturally occurring chemistry as Lane claims it did.
I don’t think Tour or Lane or anyone else can actually start with alkaline vent chemistry and explain how the first cells could form. I think in the future Lane might leave his mark in cancer or aging research, but he has not demonstrated that his ideas about the OOL are even possible so why should anyone assume that they are plausible? Tour constantly explains why OOL speculations are unfounded and I have never seen evidence for any of their speculations withstand scrutiny.
If you feel that way then why not talk to him about it. Maybe you and him could have a conversation here. I think you all should try to get him to talk with you all here.
How so? When you gave me a paper I read and compared the reagents to what is available in nature according to planetary science, geology and biochemistry. The conditions that made the experiment work in the lab don’t exist in nature. How is taking the time to consider the evidence for and against a hypothesis hearsay?
These enzymes are [NiFe]-hydrogenase…