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Author | Topic: Woese's progenote hypothesis | |||||||||||||||||||||||
randman  Suspended Member (Idle past 4929 days) Posts: 6367 Joined: |
Woese concludes the following:
The types of phenotypic changes that accompanied the formation of the three primary kingdoms are of a special nature. General differences in cell architecture among the three groups are remarkable, as are their differences in intermediary metabolism, and each kingdom seems to have its own unique version of every fundamental cellular function: translation, transcription, genome replication and control, and so on. The kind of variation that subsequently occurred within each of the kingdoms is minor by comparison. Thus the mode of evolution accompanying the transition from the universal ancestor is unusual; far more novelty arose during formation of the primary kingdoms than during the subsequent evolutionary course in any one of them. It is hard to avoid concluding that the universal ancestor was a very different entity than its descendants. If it were a more rudimentary sort of organism, then the tempo of its evolution would have been high and the mode of its evolution highly varied, greatly expanded. Were the actual root of the universal tree (Fig. 4) located in the vicinity of the deepest branchings in any one of the three primary kingdoms, the above argument concerning sequence distances would not apply to that kingdom, which makes it conceivable that the universal ancestor had the basic phenotype of that group. (This argument is particularly attractive as regards the archaebacteria, for the group sits relatively close to the intersection of the three primary lineages; see Fig. 4.) However, this would still leave the problem of deriving the other two phenotypes from a third comparably complex one, which entails drastic changes at the molecular level in most functions in the cell. In my opinion the changes in overall cell structure, organization, etc., required to change one of the three phenotypes into either of the others are too drastic and disruptive to have actually occurred. Accepting all this, the only solution to the problem is for the universal ancestor to have been a progenote. pg 264 (pg 44 in the link) http://www.pubmedcentral.gov/picrender.fcgi?artid=373105&... This interests me for a couple of reasons. First, Woese acknowledges that the data is such that:
In my opinion the changes in overall cell structure, organization, etc., required to change one of the three phenotypes into either of the others are too drastic and disruptive to have actually occurred. In other words, he cannot see anyway that is feasible or reasonable for a common ancestor to evolve into what he classifies as the 3 primary kingdoms, at least if their shape and characteristics are handed down by their genes and so mutations are selected via natural selection and so the creatures' features evolve via gradual change into different creatures. This is important. He says the changes "are too drastic and disruptive to haveactually occurred." He goes on to posit a hypothetical creature, a progenote, as the "only" solution which he describes thus:
The progenote is a theoretical construct, an entity that, by definition, has a rudimentary, imprecise linkage between its genootype and phenotype (251, 256). (Extant organisms, which have precise, accurate links between genotype and phenotype, are then genotes.) The certainty that progenotes existed at some early stage in evolution follows from the nature of the translation apparatus. page 263 (pg 43 in the link) So Woese recognizes that there is a serious problem claiming that the "three kingdoms" as having evolved by observable processes that we know of today. He posits a non-observed theoritical construct as a solution. But there are problems. If there is "imprecise linkage between phenotype and genotype", then how is natural selection suppossed to work? If an organism has a beneficial trait, that trait won't necessarily be passed on and so the fact that organism survives does not mean it's progeny is more likely to. Furthermore, isn't the claim that natural selection can work with the precursor, the hypothetical (mythical?) RNA-based duplicators, of the progenote (another imagined construct). Maybe the truth is simply that the 3 primary kingdoms Woese defines did not evolve from a common ancestor at all? Edited by randman, : No reason given.
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randman  Suspended Member (Idle past 4929 days) Posts: 6367 Joined: |
Sort of hate to add the following since I do appreciate you promoting it and doing so without too much requirements for modification, etc,....
Nevertheless, just to add a small note and it doesn't really matter either way....I am not so sure it involves Origins of Life per se, as much as biological evolution since he's really hypothesizing on the period (hypothetical imo) of evolution from the first life form into the 3 primary kingdoms. Edited by randman, : No reason given. Edited by randman, : No reason given.
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randman  Suspended Member (Idle past 4929 days) Posts: 6367 Joined: |
Well, we can just wait and see I suppose. The actual forum is not that important. Hopefully, there will be some comments from others.
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randman  Suspended Member (Idle past 4929 days) Posts: 6367 Joined: |
sorry but you are trying to attack his paper based on red herrings I am not attacking his paper but dealing with the facts he raised. You seem to want to avoid those facts.
i'm not sure where you get this idea that he is saying its a problem, he says no such thing, are you even reading the whole thing or just skimming it? the gist of what he is saying is it would have to have features of all three kingdoms
Then why does he propose a progenote? I am not misrepresenting him at all here. You seem to not understand that what he proposes is that that there is no way at all for the universal ancestor to be a creature that reproduces like the creatures that descended from it. The gist of his paper is certainly not that this theoritical common ancestor simply was a mix of all 3 kingdoms, and in fact, the gist of the paper is the exact opposite in proposing a progenote!
explain to me what that has to do with NS I don't think that is possible considering your earlier misreading of his claims. Do you realize that a progenote is by definition a creature that lacks "precise linkage" as he says between phenotype and genotype? Isn't it obvious then why natural selection is an issue? Rev, to be frank with you, your comments are just ignorant. Read the OP again carefully and pay attention this time. Woese raises a problem and offers a solution. You seem to be denying several things, that he raises a problem and solution and that there is a problem or solution, and so your entire post is wholly without any substantive comment whatsoever. Edited by randman, : No reason given.
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randman  Suspended Member (Idle past 4929 days) Posts: 6367 Joined: |
This is a clear example of taking a quote out of context. Really? Read the preceding comments such as:
In principle the universal ancestor could have resembled any one of the three major types of extant organisms. It also could have in essence been a collage of all three, or have been very unlike any of them. I will argue that the last alternative is the correct one and that the universal ancestor was a progenote. Look at the statement that he is arguing that "the last alternative", that "the universal ancestor was very unlike any of them," is his position. Do you deny this is his argument?
Woese refers only to one of the three Kingdoms evolving from another. Wrong. Woese states:
In my opinion the changes in overall cell structure, organization,etc., required to change one of the three phenotypes into either of the others are too drastic and disruptive to have actually occurred. Accepting all this, the only solution to the problem is for the universal ancestor to have been a progenote. He states before this.
far more novelty arose during formation of the primary kingdoms than during the subsequent evolutionary course in any one of them. Undeniably woese is not arguing that one kingdom spawned the other 2, as you claim, but the exact opposite. His reason is that there are more differences between the kingdoms than within them, and so the changes required make it unreasonable to think that one could have evolved into another, or that even an organism similar to them could have been the common ancestor. You wholly mistake his argument. Edit to add.
Accordingly Woese proposes that all three Kingdoms evolved from a significantly simpler ancestor. Upon rereading this comment, I see your argument a little differently, but still avoiding the basic claim of Woese. Woese, in proposing a progenote, is insisting not just that the 3 kingdoms evolved from simpler forms of life similar to the 3 kingdoms, but for a very large qualitative difference. My point is that this is hypothetical, not just because it must be by definition, but because we have no examples of progenotes, do we? There are other, reasonable conclusions that can be drawn once you don't automatically assume universal common descent. For example, there is the real possibility these kingdoms did not evolve from a common ancestor. Edited by randman, : No reason given. Edited by randman, : No reason given.
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randman  Suspended Member (Idle past 4929 days) Posts: 6367 Joined: |
This is study that was somewhat snidely and rudely thrown at me by evos here at evc, apparently unaware of the problems it raised for evolutionary models.
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randman  Suspended Member (Idle past 4929 days) Posts: 6367 Joined: |
Why does he propose a progenote Paulk? Specifically, what does he mean when he says a progenote is the only possibility?
Obviously, he rejects the idea that:
the universal ancestor could have resembled any one of the three major types of extant organisms. It also could have in essence been a collage of all three, Are you arguing that a progenote is merely a collage of all three? If you are, then you disagree with Woese here. I have taken nothing out of context. You are simply avoiding his argument completely. Woese obviously raises a problem and offers a solution. You seem to want to, as Rev as well, to avoid discussing the problems and the solution he raised in favor of making baseless charges towards me. Edited by randman, : No reason given. Edited by randman, : No reason given.
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randman  Suspended Member (Idle past 4929 days) Posts: 6367 Joined: |
Let me ask you again.
Why does he propose a progenote Paulk? Specifically, what does he mean when he says a progenote is the only possibility? You seem to be avoiding both the context and substance of Woese's argument. Why?
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randman  Suspended Member (Idle past 4929 days) Posts: 6367 Joined: |
You are not answering. Why does he propose a progenote, Paulk?
A general answer that he did so in his judgement based on the evidence, blah, blah, blah,....is simply an evasion of engaging the facts here. What specific reasons does he give for proposing a progenote? What's the deal here? And no one claims that he doesn't argue for common descent. Obviously he does or he would not propose the hypothetical or perhaps mythical? construct of a progenote.
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randman  Suspended Member (Idle past 4929 days) Posts: 6367 Joined: |
I am addressing your posts. You claimed I was taking something out of context. That's total BS on your part. I asked you why he proposes a progenote to get you to deal with the facts and arguments presented in the paper. If I can get you to do that, then it becomes very clear I have taken nothing out of context, but so far you are evading the topic of the thread and hurling baseless charges.
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randman  Suspended Member (Idle past 4929 days) Posts: 6367 Joined: |
PaulK, all you are doing is dodging, and as usual in my experience, discussion with you is unfruitful because of evading the topic.
Stating " most of the mechanism for high-fidelity reproduction seem to have arisen after the division between the three kingdoms" is not an answer. All you are doing is essentially repeating the conclusion. The question is why does he propose a progenote, why does he think the mechanism for genotes (all organisms we see today) arose after the division of the kingdoms? Quite obviously the reason I asked this question is your baseless charge of taking things out of context. Woese gives specific reasons for insisting that a progenote had to be the universal common ancestor. I quoted those reasons and thus took nothing out of context. You ignored those reasons, falsely charge I took something out of context, and continue to evade Woese's data. Since Woese's conclusions and data are the OP, you are merely clouding up the thread with no substantive comments at all. Why? Woese insists that a genote cannot be the common ancestor, and hence my language Woese "cannot see anyway that is feasible or reasonable for a common ancestor to evolve into what he classifies as the 3 primary kingdoms, at least if their shape and characteristics are handed down by their genes and so mutations are selected via natural selection and so the creatures' features evolve via gradual change into different creatures." Woese raises a problem, stating normal evolutionary processes, as we see with genotes (theoritically), cannot account for the massive differences in the 3 kingdoms. That was my point on the language you object to. Obviously, genes are involved, but not in what you call "high-fidelity" reproduction. That's why I brought up natural selection. If a trait based on genes can be selected for, but not necessarily passed on, it is not clear how such a loose reproductive process can work with natural selection because there is no reason to expect the genes that are selected for to be passed on. In terms of whether this is out of date, you are welcome to show you understand and can identify the problem Woese raises and then offer an alternative. So far, you don't seem to even understand his reasons for proposing a progenote. There are other "solutions" to the problems he raises, but we aren't going to have a fruitful conversation if you won't acknowledge those problems first since they are based on data.
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randman  Suspended Member (Idle past 4929 days) Posts: 6367 Joined: |
Rick, Woese talks about several reasons for advancing the progenote hypothesis. One particular reason, which I quoted in the OP, is that Woese does not think current observed processes of reproduction and evolution can account for the 3 kingdoms arising. That's my point.
So he advances an idea of a different kind of evolutionary process based on a different sort of creature (one might be tempted to call this a Just-So Story since we have no examples of progenotes). Now, I actually think Woese is interesting and offers an honest perspective, but imo, when evos honestly try to assess a weakness or problem and offer a solution, it is problematic for evos in general because so many evos insist the problems never exist. That's what I think is happening on this thread. An alternative to Woese's hypothesis is simply that the 3 kingdoms did not share a common ancestor. Edited by randman, : edit to change a mistake on a double negative
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randman  Suspended Member (Idle past 4929 days) Posts: 6367 Joined: |
Yea, Woese prefaces his conclusion early on by insisting that demarcating a line between life and non-life is a creationist heresy or some such, and so I think he avoids the issue of what is a life, but on the other hand, I think a progenote is considered a cellular organism.
Maybe someone more knowledgeable can clarify?
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randman  Suspended Member (Idle past 4929 days) Posts: 6367 Joined: |
Abiogenesis science has often stated that the original replicators would probably be very different from life as we observe it today. Is it your view he is talking about abiogenesis? I think he is talking about the point after that. The title of his paper is "Bacterial Evolution", is it not? You seem to be handwaving the issue away by calling it abioogenesis when Woese is talking about evolution. Known evolutionary processes cannot account for the 3 kingdoms arising, right? So why do you guys insist they arose from a common ancestor at all? It seems akin to mythmaking to me.
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randman  Suspended Member (Idle past 4929 days) Posts: 6367 Joined: |
Thanks for your comments. The molecular clock angle is interesting because it does suggest that the 3 kingdoms could not have arisen via present processes we observe today, but it also illustrates the considerable weight thrown into assumptions within evolutionary science.
Personally, I think accepting that these 3 kingdoms did not arise from a common ancestor is actually a more tenable conclusion, even if one accepts abiogenesis, which is another leap of faith imo. But if abiogenesis occurs, isn't it likely that there would be multiple instances of it, and yet would likely produce a similar type of organism based on the principles, yet discovered I might add, of chemistry that demonstrate life arising. So why wouldn't one just think that the 3 kingdoms arose via multiple origins? Of course, the whole idea of abiogenesis is barely scientific in the sense of being testable, and we have no real evidence for it, but nevertheless, even if one rejects ID and creationism, the evo insistence on a common ancestor seems more willful than fact-based.
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