Charges cause water droplets in an early-Earth atmosphere to build up pre-life chemicals.
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Who needs lightning? Key biochemicals form from static sparks
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Has anyone repeated the Urey-Miller experiment with just plain old entropic heat? Like at a hydrothermal vent. The process doesn't need to be fast. One billion years is a long time. A very long time.
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Question: where is current science as to the origin of the lipid membrane?
It's been a few years and I'm definitely out of the loop.
Is it thought now these building blocks of DNA formed first, and some sort of proto-life made lipids, that then combined with DNA and such to form the basis for the cell? Something else?
It's been a few years and I'm definitely out of the loop.
Is it thought now these building blocks of DNA formed first, and some sort of proto-life made lipids, that then combined with DNA and such to form the basis for the cell? Something else?
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Koga Onutalepo
Ars Legatus Legionis
I'm now visualizing that in a cloud, the smaller negative droplets would waft higher in the air while the larger positive ones would sink lower, creating a charge imbalance within the cloud.
Thus, lightning a bit bigger than microscopic.
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One idea is that the membrane came later and the original bounding surface was clay like material in water. The idea being that the tiny pockets of water with the various Ingredients of LifeTM was bounded by a material that could loosely bind the organic precursor materials and allow for catalytic actions and replication while being close to a liquid phase. The lipid membrane came later to allow the protolife critter to escape out of the matrix.
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The early oceans formed on a rather hot earth. That implies a very violent atmosphere with a great deal of lightning. If these prebiotic chemicals are formed by lightning, they will build up over time, unless there is an efficient mechanism to revert them back to simpler molecules. I would expect lightning and radiation to make them into bigger molecules if anything. So even if lightning strikes occur rarely close to any particular puddle, I would think a few million years of lightning would leave an ever-increasing amount of pre-biotic gunk lying around everywhere. That is not to say that Prof Zare's mechanism may not have been an equally or more important provider of prebiotic grist for the mill, but that in absence of the components reforming their original starting materials with 100% efficiency, time will inevitably produce a great deal of more complex chemical compounds on young earth. Even from apparently rare events per unit area.
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You kind of do need it to happen fast enough that it doesn't all wash down into the deep ocean before it can accumulate somewhere else.
Unless, of course, hydrothermal vents in the deep ocean were involved in abiogenesis, in which case having it all wash into the deep ocean is a feature, not a bug.
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I'm glad to see some verification of the Miller/Urey* experiment being done, I'll now have more ammo when discussing the topic of abiogenesis as it relates to biological evolution. The safety risks in the original experiment mean that there hasn't been a ton of reproduction, and creationists have used that a lot to argue against its findings.
For those interested in abiogenesis, I recommend learning about proto-cells formed in the lab from just lipids in simple solutions, and from there more recent progress made in understanding precursor cells. We didn't jump from these animo acids to life, so figuring out the basic functional building blocks like liposomes is key - and they are shockingly functional IMO even at that level.
https://en.wikipedia.org/wiki/Protocell
"Jeewanu protocells are synthetic chemical particles that possess cell-like structure and seem to have some functional living properties.[81] First synthesized in 1963 from simple minerals and basic organics while exposed to sunlight, it is still reported to have some metabolic capabilities, the presence of semipermeable membrane, amino acids, phospholipids, carbohydrates and RNA-like molecules.""
"In a similar synthesis experiment a frozen mixture of water, methanol, ammonia and carbon monoxide was exposed to ultraviolet (UV) radiation. This combination yielded large amounts of organic material that self-organised to form globules or vesicles when immersed in water."
https://www.science.org/content/article/lab-created-protocells-provide-clues-how-life-arose
https://pubs.acs.org/doi/10.1021/acsnano.2c08093
https://pmc.ncbi.nlm.nih.gov/articles/PMC6435886/
https://www.nature.com/articles/s41467-017-00177-4
(Miller did all the work, and Urey even expressed that his name shouldn't be on the paper. I think Miller should at least get the top billing, though he usually doesn't)
For those interested in abiogenesis, I recommend learning about proto-cells formed in the lab from just lipids in simple solutions, and from there more recent progress made in understanding precursor cells. We didn't jump from these animo acids to life, so figuring out the basic functional building blocks like liposomes is key - and they are shockingly functional IMO even at that level.
https://en.wikipedia.org/wiki/Protocell
"Jeewanu protocells are synthetic chemical particles that possess cell-like structure and seem to have some functional living properties.[81] First synthesized in 1963 from simple minerals and basic organics while exposed to sunlight, it is still reported to have some metabolic capabilities, the presence of semipermeable membrane, amino acids, phospholipids, carbohydrates and RNA-like molecules.""
"In a similar synthesis experiment a frozen mixture of water, methanol, ammonia and carbon monoxide was exposed to ultraviolet (UV) radiation. This combination yielded large amounts of organic material that self-organised to form globules or vesicles when immersed in water."
https://www.science.org/content/article/lab-created-protocells-provide-clues-how-life-arose
https://pubs.acs.org/doi/10.1021/acsnano.2c08093
https://pmc.ncbi.nlm.nih.gov/articles/PMC6435886/
https://www.nature.com/articles/s41467-017-00177-4
(Miller did all the work, and Urey even expressed that his name shouldn't be on the paper. I think Miller should at least get the top billing, though he usually doesn't)
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This is the internet, where do you get off making such an information-dense post?
I'm going to have to go watch a cat video to compensate.
(In all seriousness, I sense I'm about to spend a couple hours down a rabbit hole. Thanks for that post.)
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Is it know why the smaller droplets become negatively charged (or phrased differently, why they attract electrons), and the larger droplets positively charged? Does it have to do with the relative curvatures of the surface of the droplets?
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This fills the gap I had in my understanding of the genesis of life. The puddle and lightning thing seemed unlikely alone. But if the water itself, when agitated properly, produces the kind of ionizing effect needed to produce biologically significant compounds that lightning does, that's huge, since that's going to happen orders of magnitude more often on a micro scale than lightning can do on a macro scale (even if lightning back then was far more prevalent than it is now).
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Maybe, but that's also looking at the end product of evolution and trying to draw a direct comparison between features and functions. Which is a common 'mistake' of creationists and their 'irreducible complexity' argument. The functions and features of the lipid membrane today does not require that it is at all similar to how it started. That's what makes tracing the evolution of single-cell organisms, bacteria, and viruses back through time simultaneously so fascinating and frustrating. Evolution has a habit of hijacking unrelated features or functions that -- because of unknown conditions or pressures -- suddenly offered a survival benefit. And those conditions or pressures become rapidly more difficult to identify and dissect the further back in time you go.
-edit- And all this is further complicated by the fact that we don't have anything against which to compare our research into the formation of life. We don't have samples of proto-cellular compounds from before, during, and shortly after abiogenesis. We're feeling around in the dark, for lack of a better description. Or perhaps a better description might be trying to assemble a puzzle with an unknown number of pieces, and nothing but our fingertips to guide us.
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Pretty much. The smaller the radius of curvature, the more electrons concentrate there. This, BTW, is why a Van deGraf generator will cause your hair to rise.
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Nature plays with the tail ends of probability distributions. There could have been numerous sources of precursor chemicals - regular lightning strikes, micro-lightning from droplet sprays, comet and asteroid impacts, deep sea vents of the hot and cold kinds - and all that gunk added up. Given lots and lots and lots of time and energy input, something was bound to evolve out of the ooze.
The result is the talking monkey typing this on the latest silicon.
I'd like to know more about the most basic lipids or amino acids that could replicate on its own.
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I used to be. A combination of going to university for a biology degree and my church deciding that Trump is better than Jesus pushed me out.
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When I saw the title I thought they were going to talk about those water fountains kids play in,
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Great article. Great science. Probably be a while before someone funds something like this again.
Think of the commercialization opportunity! Someone could sell a "Trump Water Bottle" with electrodes coming out of it, to use as a MAGA Phone Charger! Shake & Charge!
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It has always struck me that just because we have a single genetic code throughout the entire domain of life (including viruses), does not mean to say that was always so. We may well have started with many variants, and possibly some wildly different starting points, but as long as they were all carbon based, a few billion years is plenty of time for the current biochemistry to eat all of the evidence of its earlier genocides. And I doubt that we will ever be able to get any meaningful biochemical data out of 4 billion year old microfossils. And some viruses read DNA and/or RNA in rather more adventurous ways than do even prokaryotes. Is this a later evolutionary development, or a relic of a past subsumed system?
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The Last Universal Common Ancestor (LUCA) was very probably not the first living organism. Theories like RNA World postulate a series of very basic critters capable of some level of genetic replication that existed prior to LUCA and that eventually got subsumed by something else and then helped the transition to the putative LUCA ancestor. According to current thinking, LUCA did have at least some of the modern codons and was capable of translating RNA into protein. So it's actually a fairly advanced package and did not just show up de novo.
So yeah, you're probably correct.
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As far as I know, the hydrothermal vents are also good candidates (even if sometimes rejected).
A good general review (IMHO): https://www.researchgate.net/public...otic_Stage_and_the_Evolution_of_Life_on_Earth
We should also acknowledge the pioneering works of Ponnamperuma, Fox and Oro among many others :
https://thuppahis.com/2024/09/26/cy...ncisive-scientific-researcher-in-world-class/
https://en.wikipedia.org/wiki/Sidney_W._Fox
https://www.sciencedirect.com/science/article/abs/pii/0003986161900339?via=ihub
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It could have simply been that DNA-RNA was the most efficient and robust system, and with evolution, efficiency is often a key determining factor in long-term success vs competitors. Or there might have been a surplus of DNA-RNA compounds that allowed its users to reproduce more quickly and squash the competition, possibly even being the first extinction-level event. Just two of an almost unfathomable number of possibilities and pressures, of features and functions that pushed early life to evolve the way it did. And because we have no samples to examine, we just don't have a good way of answering those kinds of questions definitively. We can only give a broad range of possibilities with the information we've managed to collect and postulate from there.
Honestly, I don't think we're ever going to find a definitive answer to how life originally formed. It all happened too far in the past, and the information necessary to put all the pieces together -- indeed, the very pieces themselves -- have long since been destroyed. Some, or perhaps many of those pieces, were destroyed by life itself.
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DNA is more stable than RNA so it makes sense that relatively long lived organisms would want their backup store to be DNA rather than RNA; we've evolved similar concepts for computer design. But it is possible that the earliest self-replicating organisms used a different set of nucleic acids capable of remaining stable in the conditions of the early Earth, and then natural selection eventually left us with the present system. It could be that that evolution happened rather quickly in the Earth-age timescale leaving billions of years to evolve both whales at one end and the Earth's dominant life-form (bacteria).
I shouldn't push the computer analogy too far, but imagine future archaeologists coming across an iPhone and doing a Paley on it: "Such a complex structure could not have arisen by direct human planning, a God must have shown them how to do it." If you know about the progression through relays, valves, discrete transistors and ICs on the one hand, and punch cards, paper tape, magnetic tape and so on on the other, then God can be ruled out and simple human creative stumbling be substituted.
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There is also some stratification effect of ions in water at the ocean’s surface. Chloride ions are more concentrated than sodium ions in the top few layers of molecules at the water-air interface and then end up being the dominate ion in sea-spray aerosols.
I am not sure if that has some connection to the droplet size or not though.
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Absolutely. The "intermittent and dispersed" argument never seemed compelling to me, unless these freshly made prebiotics not only dispersed, but also degraded quickly. But in the absence of metabolic processes, I haven't heard much about mechanisms that would tend to destroy these molecules either.
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This is a great analogy to the 'irreducible complexity' argument. If all you have is stone tools and an iPhone to 'compare' human technologies, the leap between them seems impossible, that there must have been some kind of external force or entity that crossed that gap for us. It's not until you have the myriad different tools and systems that humanity built throughout thousands of years of civilization, that the picture becomes clear enough to see how we went from stool tools to nano-scale technology capable of controlled manipulation of individual atoms.
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Not this Jeewanu crap again. With respect, from your own reference:
"Bahadur's publications were ambivalently received, and the overall attention of the scientific community seemed limited since Krishna Bahadur and his co-workers reported that the Jeewanus are alive (a striking statement), the team changed the protocols frequently and documented them somewhat idiosyncratically.[1] Bahadur defined "living units" as "[...] those which grow, multiply, and are metabolically active in a systematic, harmonious, and synchronized manner".[5][11] Then, NASA's Exobiology Division tasked two biologists in 1967 to review and evaluate the literature so far published by Krishna Bahadur (not to replicate the experiments) on the synthesis and characteristics of the Jeewanu.[11][18] The two NASA biologists did not debate whether these three criteria are an adequate definition of life, but whether the Jeewanu satisfy these criteria.[18] The NASA report concluded that "the evidence presented on these three points is on the whole unconvincing". The report also stated that the postulated existence of these living units has not been proved and "the nature and properties of the Jeewanu remains to be clarified."[18]
I would submit that there is a reason no one is chasing these supposed protocells today. They never truly existed. These sincere folks were probably looking at real lipid self assembly along with the products of actual life that contaminated it.
This experiment, if valid, would have been worth a Nobel Prize, and would have been replicated 100s of times. The reason it wasn't is probably that people tried, couldn't replicate the claimed results, and published nothing.
...I'd also be deeply interested in how scientists in the 1960s even verified that they had proper de novo "RNA-like" molecules. To the best of my knowledge, the ability to see the dynamics of such a process, or to synthesize and verify such products, was still decades away.
(After all, the interesting thing about RNA is what it DOES. Getting something that superficially resembles it while doing none of what RNA does might be interesting, but it's not related to potential abiogenesis.)
Potential abiogenesis routes are a fascinating subject, but so far nothing has been convincing. We're still at the stage of throwing shit at the wall and waiting to see what sticks—telling "just-so" stories.
Personally, I suspect we'll either never know, or that panspermia is correct, or both.
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Young Earth Creationism (YEC) is not a consensus or majority view among Christian evangelicals.
I'd add that evangelicalism is a very broad tent—it consists solely of conservative views about the reliability of holy books, and a cultural practice of trying to transmit their faith to others. There are Catholic evangelicals, for instance. (The Catholic church teaches that the Earth is old and that evolution is an accurate scientific theory.)
Really the only thing most evangelicals reject is abiogenesis, and as a consequence, most forms of descent from a common ancestor.
They'll often express doubts about "evolution", but I find that if you find out what that actually means to them, you find that they accept nearly every bit of evolution that you do.
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Er, but Paley's point was exactly that iPods (or watches) are created by intelligent agents/a directed process.
Like I see where you're coming from, but your example presupposes the exact point under contention there.
I don't think anyone disputes whether intelligent beings can make complex objects on geological timescales.
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Unfortunately "something was bound to evolve out of the ooze" is not a scientific statement.
(I think you're probably engaging in a bit of circular logic there: it seems inevitable to you because you already assume that it can and did happen, and that Earth must be typical, ergo it's bound to happen.)
On the basic lipids or amino acids that can replicate on their own, to the best of my knowledge, the answer is quite simple: zero.
We've seen self-assembling lipid structures, but these rely on preexisting lipids and these lipids do not create new lipids.
It's really the cruz of the difficulty with all of these early life/protocell/abiogenesis experiments—only nucleic acids have been found to actually replicate, and even they, in most cases, requires a lot of extra machinery.
It's all well and good to create relatively sophisticated molecules by random chance in a lab, but so far none of these Miller-Urey-esque experiments have produced anything that is self-replicating.
Indeed, we can't make them, either. Oh, sure, we can do the Craig Ventner and rearrange the parts of existing cells. But that's isn't the same as being able to create a self-replicating cell from scratch.
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This has generally been my thought process as well.
To the degree that I actually feel a bit twitchy when it's asserted that we know abiogenesis occurred—not because I have some other pet theory I prefer, but because I really dislike taking leaps over our vast ignorance of the subject.
We don't actually KNOW that abiogenesis occurred, much less how. We assume it did. It's very important to maintain clarity about the difference between assumptions and known facts.
The truth is that we don't know what happened. What we know is that life is here and has been here for a long time. Everything else is interesting educated guessing.
And like you, I suspect we will probably never know.
In fact, it would almost be too much to hope to think that life has one virtually unchallenged route from prebiotic organisms—say, that RNA/DNA are the only good way to make life, and that they are so common or inevitable in some sense that all or nearly all life will have them (assuming other life does exist—it may not).
Because then at least we could put some scientific pieces together, make some reasonable guesses.
Otherwise, we're talking about a unique historical event, or events, in the remote past, far beyond our ability to discern, not just what could have happened, but what actually did, in fact, happen.
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I actually think "irreducible complexity" is a much more interesting argument than it is given credit for.
Well, besides the fact that it's perfectly useless for learning about biology—we can't even adequately characterize existing biological systems, much less reliably chart out the potential possible histories of those systems.
So, I think it's a very clever, interesting idea, but you can't actually use it for anything...much less the uses that Behe tried to put it to, although I found his look at blood systems interesting, if unconvincing.
Mind, I also don't think that even IF Behe et al. proved that a system was irreducibly complex, that the only possible conclusion would be that the system was designed by an intelligent being. That absolutely does not follow.
"Simple undirected chance mutations working via natural or sexual selection is not sufficient mechanism to account for this system" is nowhere close to being "this system must have been created by an intelligent designer".
Anyhow, I do hate it when I hear people ridicule the notion, as though it were stupid. (Which you did not do, of course.)
Although I think you're right to point out that essentially everyone's creation myth involves a lot of hand-waving...that human technology has a perfectly explainable origin, but might seem mysterious if we weren't actually aware of the history...well, it doesn't really say anything about the origin of life.
But it says a lot about the fallibility of human probabilistic reasoning in situations of highly incomplete information and vast historical gulfs—whether we're hand-waving the massively complex issue by saying that a god obviously created it, or that they obviously didn't.
The truth is, neither is obvious, and our sense of probability here is so off that we really can't say much that is likely to be correct.
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If the idea had not come about as a bad-faith rebuttal to evolution, it might not be treated so derisively, but as it stands? That's all it has ever been -- a way for the religious to stick their fingers in their ears and ignore mountain ranges of evidence supporting evolution...and nothing to contradict it. Even the 'missing link' notion some of them like to tout is nothing but a red herring. Because it's not 'missing.' It stopped being missing long before they co-opted the term. We found the links tracing our evolutionary ancestry back millions of years to the time before humans were humans. That's proof as concrete as it gets in science. Evolution is a theory more challenged than any in history, and it has withstood every single attempt to disprove or discredit it. And with flying colors every single time.
If there IS a point of 'irreducible complexity' in evolution -- to prove or disprove -- it is at the moments where life initially formed. But we do have strong supporting evidence about the kinds of conditions that may allow for it to happen on its own, spontaneously. But not if those conditions existed at the right times, though there are small hints that some of them may have been present on primordial Earth. So certainly there's far stronger evidence in support of abiogenesis than there is for some alternative possibility, because there is absolutely no supporting evidence of any kind for any other possibility. Just unsubstantiated conjecture (panspermia) and fantasy (creationism). And all things being equal, the simplest explanation tends to be the correct one. Or maybe this is all some giant simulation being run from some external dimension by lifeforms trying to understand how life arose in their reality. It's at least as plausible as, "God did it."
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So, static electric charges, rubbing polar molecules together. Very tiny scale. Physics is wonderful, so many interesting things when we look closely
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If you read Paley's tedious book you will realise that he believed that every species was directly created by God without any intervening evolution, not by a "directed process".
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The problem with "irreducible complexity" is that it's irrelevant to evolution. If evolution could only add features, then sure, something irreducibly complex wouldn't be able to evolve. Because the key characteristic of irreducible complexity is that you can't take anything away and have the thing still work. But since evolution cannot merely add features, but can also subtract and modify features, the fact that some system wouldn't work if you took any one element away is irrelevant to whether it was possible to have evolved.
EDIT: To put it another way, all irreducible complexity shows is the last step in evolution couldn't have been to add some entirely new element to the system. But it's actually very rare in evolution that a step adds a whole new element, anyway... so... then what?
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I tend to think that if even after we have figured out a plausible step-by-step process for abiogenesis, we'll have a hard time pointing to the one step before which there wasn't life and after which there was life. There will be a nice big gray area. Before that gray area, we'll have some organic polymers doing some simple self-replication in a soup of their monomers. We'll all agree that's not really life. After the gray area, we'll have some simple cell-like structures with a variety of interrelated chemistry going on inside. We'll all agree that's life. In between...
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