What is the most compelling, non-metaphysical theory for Abiogenesis you've learned about? (scientific, debate)
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Since so much discussion with the Theist aspect behind it has gone on, I suppose it's reasonable for A- theists to give their take on it.
I was quite impressed by a theoretical model of non - organic to organic. I shall try to find where I put my copy or link. In fact I think it might not be a bad idea to sum up the evolutionary case for abiogenesis - because it can't be denied that they are the ones looking for the answer and, if they ever find it, then it will become part of evolution theory. at the moment it's treated like the disreputable relative nobody wants to admit to.
I shall also try to find the Lab - creation of life which is supposed to be significant and the relevance of viruses and stromatolites and the like.
I might also begin with my views on the Creationist take, even before I put the case for, I can see some problems with it.
It is only fair that the Creationists have their say.
Why Abiogenesis Is Impossible
Jerry Bergman, Ph.D.
"The question on which this paper focuses is “How much evidence exists for this view of life’s origin?”
(Arq comment). Right away, we see the problem. There is very little evidence for abiogenesis - that is admitted. But there is a great difference between what is not supported by much evidence and what is impossible. A Phd should know that to talk of 'impossible' as regards the unknowns of science is a bold claim indeed.
The REAL question is whether abiogenesis can be shown to be not only possible but feasible.
"The problem of the early evolution of life and the unfounded optimism of scientists was well put by Dawkins. He concluded that Earth’s chemistry was different on our early, lifeless, planet, and that at this time there existed
...no life, no biology, only physics and chemistry, and the details of the Earth’s chemistry were very different. Most, though not all, of the informed speculation begins in what has been called the primeval soup, a weak broth of simple organic chemicals in the sea. Nobody knows how it happened but, somehow, without violating the laws of physics and chemistry, a molecule arose that just happened to have the property of self-copying—a replicator."
The article objects:
"The first step in evolution was the development of simple self-copying molecules consisting of carbon dioxide, water and other inorganic compounds. No one has proven that a simple self-copying molecule can self-generate a compound such as DNA. Nor has anyone been able to create one in a laboratory or even on paper."
We can pass over disreputable attempts to link the undeniable speculation of abiogenesis theory with the musings of Haeckel in the 1920's let alone those of Aristotle and the 'spontaneous generation theory' which has more in common with Creation than with evolution and turn to what models exist. We can also pass over the attempt to play the 'complexity' card. The first cell - the first DNA, indeed was incredibly complex. So what? Molecules are complex. Atoms are incredibly complex. Why then should not complex DNA evolve out of complex biomolecules and those from complex atoms as we know very well that they do. This is a red herring and the real question is what models exist for this process and are they feasible?
"We now realize that the Urey/Miller experiments did not produce evidence for abiogenesis because, although amino acids are the building blocks of life, the key to life is information (Pigliucci, 1999; Dembski, 1998). Natural objects in forms resembling the English alphabet (circles, straight lines and similar) abound in nature, but this does not help us to understand the origin of information (such as that in Shakespear’s plays) because this task requires intelligence both to create the information (the play) and then to translate that information into symbols. What must be explained is the source of the information in the text (the words and ideas), not the existence of circles and straight lines. Likewise, the information contained in the genome must be explained (Dembski, 1998)."
This seems total waffle. Is that the best objection they have? It is simply shifting the Question back. 'Ok if you show that life may come from non - life, where did the 'information' come from?'
The nearest thing to 'hard evidence' are the Miller/Urey experiments.
"Then came what some felt was a breakthrough by Harold Urey and his graduate student Stanley Miller in the early 1950s.
The most famous origin of life experiment was completed in 1953 by Stanley Miller at the University of Chicago. At the time Miller was a 23-year-old graduate student working under Urey who was trying to recreate in his laboratory the conditions then thought to have preceded the origin of life. The Miller/Urey experiments involved filling a sealed glass apparatus with methane, ammonia, hydrogen gases (representing what they thought composed the early atmosphere) and water vapor (to simulate the ocean). Next, they used a spark-discharge device to strike the gases in the flask with simulated lightning while a heating coil kept the water boiling. Within a few days, the water and gas mix produced a reddish stain on the sides of the flask. After analyzing the substances that had been formed, they found several types of amino acids. Eventually Miller and other scientists were able to produce 10 of the 20 amino acids required for life by techniques similar to the original Miller/ Urey experiments.
Urey and Miller assumed that the results were significant because some of the organic compounds produced were the building blocks of proteins, the basic structure of all life (Horgan, 1996, p. 130)."
These results can be overdrawn by pro -evolutionists. They do not prove how it all happened but it did show that building blocks of abiogenesis is far from impossible.
"The reasons why creating life in a test tube turned out to be far more difficult than Miller or anyone else expected are numerous and include the fact that scientists now know that the complexity of life is far greater than Miller or anyone else in pre-DNA revolution 1953 ever imagined."
Fair enough. But that just means more steps in the process.
"Although widely heralded by the press as “proving” the origin of life could have occurred on the early earth under natural conditions without intelligence, the experiment actually provided compelling evidence for exactly the opposite conclusion. For example, equal quantities of both right- and left-handed organic molecules always were produced by the Urey/Miller procedure. In real life, nearly all amino acids found in proteins are left handed, almost all polymers of carbohydrates are right handed, and the opposite type can be toxic to the cell."
Very well. So the suggestion is that the wrong kind of molecule would poison the cell? So why couldn't the right kind go to make up the 'cell' (in fact it is oversimplifying to suggest amino - acid to cell. There has to be a stage on the way to DNA and thence to the cell.
So there is a strawman argument of making the need for a plausible explanation of abiogenesis look like hard fossil proof of it. There is also the short- sighted appeal to complexity and some suspect juggling of 'odds against', together with some shifting of the goalposts, If the mechanism is explainable, what about the symbols or language or idea behind it?
Well I'll leave that there and try to summarize the case for abiogenesis being possible (in theist terms 'possible' means 'believable' ) and plausibility and feasibility of the model.
Any creationist is welcome (so far as I'm concerned) to explain the scientifically valid mechanism by which a god dunnit (hint -the Harry Potter method is not science).
Well, I can't find that mechanism that rather impressed me and there is a lot of debate about the subject. Not always easy to find it because the Net is clogged with Theist sites repeating how 'statistically improbable' abiogenesis is.
The first "living things" could have been a single self replicating molecule, similar to the "self-replicating" peptide from the Ghadiri group [7, 17], or the self replicating hexanucleotide [10], or possibly an RNA polymerase that acts on itself....
Another view is the first self-replicators were groups of catalysts, either protein enzymes or RNA ribozymes, that regenerated themselves as a catalytic cycle [3, 5, 15, 26, 28]. An example is the SunY three subunit self-replicator [24]. These catalytic cycles could be limited in a small pond or lagoon, or be a catalytic complex adsorbed to either clay or lipid material on clay. Given that there are many catalytic sequences in a group of random peptides or polynucleotides (see below) it's not unlikely that a small catalytic complex could be formed.
These two models are not mutually exclusive. The Ghadiri peptide can mutate and form catalytic cycles
Worth reading for refutation of the 'statistical improbability' argument. succinctly, the Abiogenesis mechanism is 'simple chemicals ..to..polymers to ....replicating polymers...hypercycle...protobiont......bacteria' whereas the Creationists present it as a straight simple chemicals - to - bacteria. It is of course a strawman fallacy through misrepresentation of the mechanism, which makes it easier to discredit.
The question "How do simple organic molecules form a protocell?" is largely unanswered but there are many hypotheses. Some of these postulate the early appearance of nucleic acids ("genes-first") whereas others postulate the evolution of biochemical reactions and pathways first ("metabolism-first"). Recently, trends are emerging to create hybrid models that combine aspects of both.
Researcher Martin Hanczyc supports the idea of a gradient between life and non-life (i.e. there is no simple line between the two). He thinks that building simple protocells, in the lab, is one of the first steps towards understanding more complex cells including those that may have later evolved into complex life. Hanczyc says that living cells often consist of somewhere around 1 000 000 types of molecules, whereas his labs are first aiming at creating life-like systems using around 10 molecules. His protocells display behaviors even simpler than those displayed by things like viruses (e.g. only basic motion, dividing and combining cell walls, and so on)
The RNA world hypothesis describes an early Earth with self-replicating and catalytic RNA but no DNA or proteins. This has spurred scientists to try to determine if relatively short RNA molecules could have spontaneously formed that were capable of catalyzing their own continuing replication.[79] A number of hypotheses of modes of formation have been put forward. Early cell membranes could have formed spontaneously from proteinoids, protein-like molecules that are produced when amino acid solutions are heated–when present at the correct concentration in aqueous solution, these form microspheres which are observed to behave similarly to membrane-enclosed compartments. Other possibilities include systems of chemical reactions taking place within clay substrates or on the surface of pyrite rocks. Factors supportive of an important role for RNA in early life include its ability to act both to store information and catalyse chemical reactions (as a ribozyme); its many important roles as an intermediate in the expression and maintenance of the genetic information (in the form of DNA) in modern organisms; and the ease of chemical synthesis of at least the components of the molecule under conditions approximating the early Earth. Relatively short RNA molecules which can duplicate others have been artificially produced in the lab
The lipid world theory postulates that the first self-replicating object was lipid-like.[128][129] It is known that phospholipids form lipid bilayers in water while under agitation – the same structure as in cell membranes. These molecules were not present on early Earth, however other amphiphilic long chain molecules also form membranes. Furthermore, these bodies may expand (by insertion of additional lipids), and under excessive expansion may undergo spontaneous splitting which preserves the same size and composition of lipids in the two progenies. The main idea in this theory is that the molecular composition of the lipid bodies is the preliminary way for information storage, and evolution led to the appearance of polymer entities such as RNA or DNA that may store information favorably.
There's a lot of discussion but clearly some plausible ideas about how. While it is valid and necessary to make objections to the models it is simply being too dismissive as well as scientifically unsound, not to say dishonest, to dismiss it as impossible or even unfeasible.
The RNA world hypothesis describes an early Earth with self-replicating and catalytic RNA but no DNA or proteins. This has spurred scientists to try to determine if relatively short RNA molecules could have spontaneously formed that were capable of catalyzing their own continuing replication.
I don't know if you got to check out 2 of the links I posted. Self-replicating RNA has already been developed in the lab. I was unaware of it before.
They even observed evolution-like characteristics such as mutations and natural selection in these enzymes. It's very interesting if true.
I don't know if you got to check out 2 of the links I posted. Self-replicating RNA has already been developed in the lab. I was unaware of it before.
They even observed evolution-like characteristics such as mutations and natural selection in these enzymes. It's very interesting if true.
It certainly is and I don't think I knew of it. I know Rifleman came up with some lab creation of Life (not the 1950's Urey/Miller amino acid thing) and I can't find the details now. I don't know if this is the one but self - replicating RNA is a bit more supportive info.
I recall that Rifleman mentioned Craig Ventner's creation of life.
"In a world first, which has alarmed many, maverick biologist and billionaire entrepreneur Craig Venter, built a synthetic cell from scratch.
The creation of the new life form, which has been nicknamed 'Synthia', paves the way for customised bugs that could revolutionise healthcare and fuel production, according to its maker."
I am ashamed to put the link to the hysterical and alarmist article by the Daily Mail - a reactionary rag which should have been consigned to oblivion decades ago.
I will give the link to this rancid piece of yellow journalism since it is making a point.
Venter and his colleagues basically figured out how to design a bacterial cell on a computer. Then they used genetic engineering and chemicals that are essential for life to produce an entity that’s novel but not yet a truly living version of anything that occurs naturally.
This “is the first self-replicating species that we have on the planet whose parent is a computer,” said Venter, who was careful to add that he had not created new life from scratch.
Well, Not a great deal it seems. The scientific world seems to have been remarkably silent on this and the only ones taking up the story are those squealing about 'playing God' and Creationists sites denying that this proves anything about Abiogenesis (1). It seems that all he has done is to do a computer generated copy of genome and got it to breed. The work done on self - replicating RNA does seem to be more relevant.
"RNA is the close cousin to DNA. More accurately, RNA is thought to be a primitive ancestor of DNA. RNA can't run a life form on its own, but 4 billion years ago it might have been on the verge of creating life, just needing some chemical fix to make the leap. In today's world, RNA is dependent on DNA for performing its roles, which include coding for proteins.
If RNA is in fact the ancestor to DNA, then scientists have figured they could get RNA to replicate itself in a lab without the help of any proteins or other cellular machinery. Easy to say, hard to do.
But that's exactly what the Scripps researchers did. .."
(1) one of them claimed this proved that DNA is a computer program. That is sheer cobblers. Being able to make computer models of this and that doesn't mean that they were designed by a computer, or anything else.
Last edited by TRANSPONDER; 03-22-2012 at 03:11 PM..
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Very good stuff guys.
BCD. your articles were very informative. I've been a fan of the RNA World Hypothsis for a little while. It always made sence to me. Seemed like a "natural" progression.
There was something spefically in the second article that caught my eye.
Quote:
Most of the time the replicating enzymes would breed true, but on occasion an enzyme would make a mistake by binding one of the subunits from one of the other replicating enzymes. When such "mutations" occurred, the resulting recombinant enzymes also were capable of sustained replication, with the most fit replicators growing in number to dominate the mixture. "To me that's actually the biggest result," says Joyce.
Interesting. Very interesting. I look forward to more results in the coming years. I think we may be getting close to having a working "Theory" for natural abiogenesis. But like in all discoveries with science I can't say with certainty.
Now let me throw this at ya. Where do you guys think the most likely place (environment) was where life first began?
I've heard about tidal areas, some type of hot springs, and even perhaps in deep water ocean vents. Do you think it one of these environments? Or do you think it some other environment?
Oh. AREQUIPA I would have given you a rep point but they wouldn't let me. It looks like it took a bit of effort to put that post together. And I do appreciate that. Will rep you for the post when I can.
I wouldn't like to guess. I read clays, undersea vents, volcanic activity, meteors and bubbles in sea- foam. None of them really grabbed me as convincing and so I can only say that further consideration of the proposed models may suggest the most likely conditions for allowing that to happen.
I can understand creationists reading with bemusement the serious consideration of pondslime evolving into us, but l must repeat what I said to Bar -El, I think, that the development from early cell to us is heavily substantiated by the fossil, DNA and morphological evidence and that natural selection, that proven mechanism of genetic mutation, has to be the mechanism for it.
Abiogenesis is simply suggesting a feasible model of biochemicals (which occur in interstellar gas and are therefore already present in planets when they form) to the cell via replicating RNA - DNA and thus to pondslime.
I don't say it's proven, but it is certainly not as impossible or even unlikely as creationists like to make out.
Ps. Thanks for you comments Baystater. In fact the credit belongs to the people who wrote the articles that I lifted. Talk origins is a wealth of information on the subject and Origins in genesis a wealth of misdirection and a mine of quotes.
If I was a betting man, I'd put my chips on Panspermia over Abiogenesis, though much progress has been made on both theories.
While we can already create synthetic "life" (albeit debatable) in the lab, having it randomly come up on a planet is another matter altogether, though still not impossible.
We'll never know until we discover extraterrestrial life and put it under a microscope, but I suspect the universe is full of the stuff...and it takes no stretch of the imagination or the facts of biology to understand how microscopic bacteria can evolve into self-aware multicellular creatures over 3.8 Billion years.
Those who push Goddunnit often ask; if Life arrived on meterorites - where did that life come from? Effectively they are saying that panspermia proves nothing at all - Life still had to evolve, just somewhere else. The rhetorical holding answer (since of course nobody knows one way or the other) would be to suggest that perhaps the other planet it evolved on had the clear fossil evidence of Abiogenesis that (of course) we wouldn't have here.
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at the moment it's treated like the disreputable relative nobody wants to admit to.
) and plausibility and feasibility of the model. 
Very interesting. I look forward to more results in the coming years. I think we may be getting close to having a working "Theory" for natural abiogenesis. But like in all discoveries with science I can't say with certainty.
