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Author | Topic: Dr. Schwartz' "MIssing Links" | |||||||||||||||||||||||
RAZD Member (Idle past 1427 days) Posts: 20714 From: the other end of the sidewalk Joined: |
He could also just be making another case for punctuated equilibrium, hard to say at this point.
Amazon book link: The Human Fossil Record, 4 Volume Set by Jeffrey H. Schwartz, Ian Tattersall, Ralph L. Holloway, Douglas C. Broadfield, Michael S. Yuan quote: He is the lead author in the list, so it seems he has the creds. I'm with Subbie here (who posted while I was composing... ) compare Fiocruz Genome and fight Muscular Dystrophy with Team EvC! (click) we are limited in our ability to understand by our ability to understand RebelAAmericanOZen[Deist ... to learn ... to think ... to live ... to laugh ... to share.
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RAZD Member (Idle past 1427 days) Posts: 20714 From: the other end of the sidewalk Joined: |
We see sequences of different species, A-B-...-H, Unless you are no longer refering to the picture, "A" is actually modern chimp and "L" and "M" are neander, if memory serves.
Punctuated Equilibrium expains why we see this pattern, and Schwartz seems to be advocating a particular mechanism for this. A genetic mechanism, if I understand his reasoning on the few sites I have been able to access.Jeffrey H. Schwartz, University of Pittsburgh quote: Jeffrey H. Schwartz, University of PittsburghThese courses are in Anthropology rather than Biology, which may help indicate where he is coming from. It would be interesting to read one of his books, particularly his "Sudden Origins: Fossils, Genes, and the Emergence of Species" ($2 used Paperback). One thing we can be certain of though, is that creatortionistas will have a field day with quote mines, as they have with Gould. Enjoy. ps -- seen the latest Tom\Dancing Bug with the neanders and the gecko? compare Fiocruz Genome and fight Muscular Dystrophy with Team EvC! (click) we are limited in our ability to understand by our ability to understand RebelAAmericanOZen[Deist ... to learn ... to think ... to live ... to laugh ... to share.
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RAZD Member (Idle past 1427 days) Posts: 20714 From: the other end of the sidewalk Joined: |
I don't understand why such a big deal is made out of this notion of constant gradual change. Does anybody even believe it any more? No biologist I know of speaks of constant change, but all "dating" by "molecular clocks" use a uniform rate - mtDNA Eve, y-chromosome Adam, etc. - which is why I find such dating questionable. compare Fiocruz Genome and fight Muscular Dystrophy with Team EvC! (click) we are limited in our ability to understand by our ability to understand RebelAAmericanOZen[Deist ... to learn ... to think ... to live ... to laugh ... to share.
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RAZD Member (Idle past 1427 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Well he is NOT on the "100 scientist list" at DI:
http://www.discovery.org/...leFiles/PDFs/100ScientistsAd.pdf OR the one at AiG:Bios | Answers in Genesis For what that is worth. compare Fiocruz Genome and fight Muscular Dystrophy with Team EvC! (click) we are limited in our ability to understand by our ability to understand RebelAAmericanOZen[Deist ... to learn ... to think ... to live ... to laugh ... to share.
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RAZD Member (Idle past 1427 days) Posts: 20714 From: the other end of the sidewalk Joined: |
What is the difference between a change that happened and was then put on the shelf just in inventory, only to be taken down and used during times of stress, and a "just in time genome manufacturing system" where things are expressed when produced and the successful ones kept? Timing. In one case you have some solutions "in the bank" waiting in case of need. In the other you have to come up with the solution when already in jeopardy. Personally I would call these "neutral" mutations that increase diversity within a population. As it moves into stasis mode the amount of diversity is not checked except by population size. If this population is increasing then there is opportunity for increased diversity that gives it more future potential to deal with stress situations (even if one such is just geographical dispersal with outer populations being more diverse from the central population).
If the mechanism does not change due to the "heat shock proteins" then where do the changes that somehow lie dormant for "myriad years prior" come from? The "heat shock proteins" are overwhelmed by the situation, and this allows the kinds of mutations, ones they normally prevent from occurring, to occur, resulting in stress response increased mutation rates -- as we have seen in some bacteria. These appear to be two different mechanisms, that can each supply "solutions" to stress situations, in different ways. The "neutral" mutation one is a more standard concept. I would want to read his book before making judgment though. Enjoy. compare Fiocruz Genome and fight Muscular Dystrophy with Team EvC! (click) we are limited in our ability to understand by our ability to understand RebelAAmericanOZen[Deist ... to learn ... to think ... to live ... to laugh ... to share.
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RAZD Member (Idle past 1427 days) Posts: 20714 From: the other end of the sidewalk Joined: |
But if they normally prevent the mutations from occurring, how do the shelves get stocked in the first place? If the scenario you describe is in fact what happens, what we would be seeing is "stress response increased mutation rates" and not the expression of some trait that was stocked on the shelf, lying dormant, for use "just in case". I read this as (possibly) two mechanisms, two layers, the first stocks the shelves with generic (heh) solutions and diversity, and the second allows what would normally be deleterious mutations to be expressed (along with more neutral and beneficial ones). This would broaden the number of possibilities beyond the stock generic ones, and it could begin to occur in a generation or so. I've ordered his book "Sudden Origins: Fossils, Genes, and the Emergence of Species (Paperback)" to see what he says there ($2 used), so give me a week to get and read. If this is so, then I don't see this as challenging evolution so much as providing a mechanism for PunkEek (and fodder for creatortionistas and IDologists). Enjoy. compare Fiocruz Genome and fight Muscular Dystrophy with Team EvC! (click) we are limited in our ability to understand by our ability to understand RebelAAmericanOZen[Deist ... to learn ... to think ... to live ... to laugh ... to share.
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RAZD Member (Idle past 1427 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Schwartz is just an anthropologist venturing outside his field. I've tried to find a reference to his degree and school without luck. This was my first impression, but I'm hesitant to pronounce such without actual evidence.
The article itself appeared in the February 9th issue of Biological Theory. Subbie had a link to the article that didn't work for me, this one seems to work:
I agree with your view, thanks for the link (I'm sure we'll see more on this from the creos & IDos). Still I am interested to see what he has to say. If nothing else this may form a basis for a discussion on molecular basis for PunkEek and more review on stress relations to mutations. Thanks. ps - we could invite him to this thread, and that may answer the questions we have eh? Edited by RAZD, : ps compare Fiocruz Genome and fight Muscular Dystrophy with Team EvC! (click) we are limited in our ability to understand by our ability to understand RebelAAmericanOZen[Deist ... to learn ... to think ... to live ... to laugh ... to share.
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RAZD Member (Idle past 1427 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Cool.
And welcome to the fray molbiogirl. compare Fiocruz Genome and fight Muscular Dystrophy with Team EvC! (click) we are limited in our ability to understand by our ability to understand RebelAAmericanOZen[Deist ... to learn ... to think ... to live ... to laugh ... to share.
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RAZD Member (Idle past 1427 days) Posts: 20714 From: the other end of the sidewalk Joined: |
jhs, Dr. Schwartz, welcome to the fray.
My dad taught biology at the U of Mich for many years before moving to Harvard, and he brought us up on evolution. I have studied some biology in university but not majored in it. We often talk about evolution these days, since my interest in the creation v evolution debate and his retirement. He knew Gould and Mayer and met Fischer. One of his biggest complaints about molecular biology is the seeming mental fixation on gradualism, which he says is not part of classical biology. I have to agree with him, particularly on the issue of "genetic clocks" because the assumption of a steady rate of mutation is at odds with the evidence, particularly when other selection systems can be in play (such as sexual selection).
Cells' molecular (DNA etc) are not constantly changing in any significant way. Mutation rate (a combination of UV-induced change and transcription error) is extremely low, c. 10 (superscript -8 to -9) - and mutation can affect any cell, not just gamets. We suggest that spikes in stress that exceed an organism's capacity to produce sufficient stress proteins to maintain DNA homeostasis represent a possible mechanism. The way I see this is that you have an organism under survival stress situation (environment or climate change) and this causes higher mutation rates. We've seen similar in bacteria, so this is no big surprise (a cell is a cell). But I don't see how this challenges the concept of evolution - the change in hereditary traits in populations over time - other than to provide a mechanism for increase mutations in stress situations and which are then still selected by their fitness to the changed condition. If anything this is a genetic mechanism for the change part of punk-eek, thus making between the two a more robust cause and effect situation for sudden change in the geological record. Certainly it does not challenge the theory of common descent or the increase in diversity accumulating over time between species that have separated into daughter, granddaughter, etcetera species. Yes it will make the job of the paleontologist harder to try to find examples of such quickened change in the fossil record, and exciting at the same time to see if one can be found. It will make the job of the geneticist more interesting to have to look at rates of change and possible changes to genetic clocks. But it won't change cladistics significantly, whether by morphology or genetics (or both), and it won't change places where we know gradual change has occurred (see The Foram Fossils: A Classic Tale of Transition), so overall it does not disrupt modern evolutionary biology much that I can see. Not any more than Punk eek did. Perhaps you can explain why you think it is so revolutionary? Enjoy. ps - I'm reading your book "Sudden Change" but have not got beyond the beginning yet. My first impression is that it is weighed down by listing virtually every saltationist from Cuvier on, and it's relevance to the modern synthesis of evolution. You seem to draw a line between gradualistic darwinism and modern synthesis evolution, when one has grown out of the other with increased information. Edited by RAZD, : . Edited by RAZD, : name Edited by RAZD, : . compare Fiocruz Genome and fight Muscular Dystrophy with Team EvC! (click) we are limited in our ability to understand by our ability to understand RebelAAmericanOZen[Deist ... to learn ... to think ... to live ... to laugh ... to share.
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RAZD Member (Idle past 1427 days) Posts: 20714 From: the other end of the sidewalk Joined: |
You're right that it's a bad assumption; but I've had pretty intimate exposure to molecular phylogenetics through my wife's work and while I certainly would claim any kind of authority, it's obvious to me that geneticists aren't ignoring what we now know about substitution rates. I've seen some evidence of this Yet whenever they talk about a genetic clock they also talk about a steady rate of change. One could include variability by having high and low rates and short and long histories. To me the "clocks" are very approximate because we do not know what past rates were at different stages. What they need to do is tie genetic change to fossils so they can measure changes in rates. This would also be able to prove or disprove Dr Schwartz's theory. Enjoy. Edited by RAZD, : finished compare Fiocruz Genome and fight Muscular Dystrophy with Team EvC! (click) we are limited in our ability to understand by our ability to understand RebelAAmericanOZen[Deist ... to learn ... to think ... to live ... to laugh ... to share.
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RAZD Member (Idle past 1427 days) Posts: 20714 From: the other end of the sidewalk Joined: |
As with radiometric dating, sometimes the technique can be applied very well, sometimes it can't, and we're developing a better understanding of how and where the technique can be successfully applied. Schwartz is mentioned in the article. My main criticism of molecular clocks is that it cannot differentiate between survival selection and sexual selection. In the case of human evolution there is pretty good evidence for fisherian runaway sexual selection, particularly in the female (with some characteristics being then carried into the males: long hair, fair apparent bare skin, permanently full breasts, childlike features, etc) carried to their practical limit (where they start impinging on survival success), and likewise with large brain size (resulting from selection for creativity, but reaching the point where birth is a challenge). These two element probably did not happen at the same time, so there were -- IMH(ysa)O -- at least two sequences of this runaway sexual selection operating at different times, possibly on different sexes. Now when we compare "molecular clocks" for mtDNA Eve and yChrom Adam what do we see? More change in Eve than in Adam? Longer change in Eve than in Adam or slower change in Adam than in Eve? We don't know. There is no connection to fossils, hard data, to be able to say at this point.
He is an example of the worst kind of scientist one can imagine, one who just like creationists lets his ideas about the way the world must be govern his acceptance and interpretation of evidence. I am finding just this narrow mindedness in his review of fossils so far in my reading of his book. There are a couple of problems I'v noted so far of possibilities he just has not looked at, and evidence he has not (yet) discussed. Of course this book is 8 years old and there is new evidence since then, but I believe there was evidence then that has been neglected. Unfortunate. Enjoy. compare Fiocruz Genome and fight Muscular Dystrophy with Team EvC! (click) we are limited in our ability to understand by our ability to understand RebelAAmericanOZen[Deist ... to learn ... to think ... to live ... to laugh ... to share.
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RAZD Member (Idle past 1427 days) Posts: 20714 From: the other end of the sidewalk Joined: |
My understanding is that they're reliably stable over sufficiently short periods of time, Those periods being part of the observed history of change in the genes. Extrapolating that to 200,000 years is preposterous. Enjoy. compare Fiocruz Genome and fight Muscular Dystrophy with Team EvC! (click) we are limited in our ability to understand by our ability to understand RebelAAmericanOZen[Deist ... to learn ... to think ... to live ... to laugh ... to share.
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RAZD Member (Idle past 1427 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Local molecular clocks use fossil divergence dates as calibration points. This paper, for example, employs such clocks and its results are quite congruent with dates inferred from fossil data when applicable. While this is a step in the right direction (compared to the molecular adam and eve dates) I still have some problems with it: they use four calibration dates - 63Ma, 45Ma, 25Ma and 14Ma - based on the fossil evidence for last common ancestor (LCA) congruent with the branching of these clades ... and then give us average rates of change for each segment in between while saying that these are the actual rates of change in those groups for those periods. Correct me if I'm wrong, but this appears to be the same kind of error in thinking that I objected to originally
Message 52 My main criticism of molecular clocks is that it cannot differentiate between survival selection and sexual selection. In the case of human evolution there is pretty good evidence for fisherian runaway sexual selection,... Different rates of selection of specific mutations for change versus rates of selection under stasis conditions would mean different rates of change at different times showing up in the DNA development over time. I also notice that this paper focuses on non-coding DNA changes -- not the ones leading to the changes that would result in speciation and selection of novel features. I suspect that if I divide the DNA into coding sections and non-coding sections and assume that a specific mutation can occur in one OR the other that
This would explain the apparent anomaly of slower rates in the non-coding sections when there is selection for longer life or larger brains. At least one other study have shows much higher rates of mutation selection in humans than in chimpanzees (UCR, aug 2004): http://www.newsroom.ucr.edu/cgi-bin/display.cgi?id=875
quote: It seems to me you have to compare the whole genomes and differentiate between coding and non-coding mutations to get a more complete picture of what went on. I expect this to be done and await the results with curiosity. My main point, however, is that the rate of mutation selection changes under different selection conditions, that you cannot assume a steady rate over any period of time without knowing those selection conditions, and thus molecular clocks cannot be used to determine when speciation - or selection of specific features - occurred. Am I wrong? Enjoy. compare Fiocruz Genome and fight Muscular Dystrophy with Team EvC! (click) we are limited in our ability to understand by our ability to understand RebelAAmericanOZen[Deist ... to learn ... to think ... to live ... to laugh ... to share.
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RAZD Member (Idle past 1427 days) Posts: 20714 From: the other end of the sidewalk Joined: |
They ARE the actual amounts of change in the branch between the LCA and the taxon in question. Not to belabor this, but they are the average rates, by definition. You do not know when each individual fixed selected mutation occurred, you don't even know if half occurred in the first half of the time period and half occurred in the second half or whether 90% occurred in the first half and 10% in the second. All you have is (n) mutations occurred in (t) time and the average rate of mutation over time (t) was (n/t). Within that time period (t) the specific rate of change could have varied considerably: you don't know.
I fail to see the relevance of this. They would de facto have different rates of fixing selected mutations.
This is irrelevant to the general 'accuracy' of local clock calculations. ZThe goal of such calculations is not to make such differentiations. Your criticisms seem similar to Paul Nelson's criticism of molecular phylogenetics as being a diversion because they do not explain what the mechancim behind the changes is. Again the rate of fixing selected mutations would be de facto different under punctuated versus stasis conditions.
Well of course, but criticising a paper in which the goal was not to do that for not doing that seems superfluous. You were the one that introduced the paper in answer to my criticism. If it doesn't do that it is not my fault.
Yes. Since local molecular clocks do not rely on any assumptions about mutation rates or rate differentials, a sufficiently large data set will nto suffer from potential short term bursts of mutation and selection or the lack thereof. Nor will it be able to identify short term bursts or conditions under which they may apply. Thus it will be unable to identify when a period could be high rate or low rate. By identifying average rates as uniform rates over long periods it also ignores the fact that different rates occur during different times. One thing I do note from your paper is that the different rates are significantly different even in spite of the averaging of the rates over the time periods involved. To me this is validation that different rates occur regularly during evolution. I would think that the question of rate changes and maximum rates of change would be of high interest. When you look at speciation events, such as Pelycodus(1):
quote: We see a gradual trend to larger size with a branch that reverts to a smaller size at a different (faster) rate of change than the long term trend before it settles into a new long term trend. It is logical for me that the rates of selecting and fixing change away from other daughter species would be higher for one or both than the average rate of selecting and fixing change. This would make understanding the magnitudes of different rates of fixing selected mutations fairly critical to the understanding of speciation and the causes of different rates. Especially if you are doing studies involving multiple speciation events or periods of intense selection pressure. Different rates of selecting and fixing mutations is part of evolution, and understanding those different rates, and the conditions under which they occur, is also part of understanding evolution. Enjoy. Reference:(1) Lindsay, Don, "A Smooth Fossil Transition: Pelycodus, a primate" Don Lindsay Archive on-line, 25 April 1997 accessed 18 Feb 2007 from A Smooth Fossil Transition: Pelycodus compare Fiocruz Genome and fight Muscular Dystrophy with Team EvC! (click) we are limited in our ability to understand by our ability to understand RebelAAmericanOZen[Deist ... to learn ... to think ... to live ... to laugh ... to share.
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RAZD Member (Idle past 1427 days) Posts: 20714 From: the other end of the sidewalk Joined: |
ALL HUMANS AND ANIMALS HAVE TO HAVE THESE THINGS IN COMMON: Do humans have to have them twice then? have them twice then? Animal - Wikipedia
quote: The sad thing about your list is that it is so easy to find correct information: any (good) encyclopedia should have this information. One should try to learn first, rather than make such ignorant posts.
But those whose whol goal is to deny God say; "Duh, I guess the similarities means dat, uh, my ancesotor was a mouse, yeah, uh-huh, uh-huh." What about all the christians (to say nothing of people of other faiths) that don't have a problem with evolution and the study of the biological sciences? What do they say? Enjoy. compare Fiocruz Genome and fight Muscular Dystrophy with Team EvC! (click) we are limited in our ability to understand by our ability to understand RebelAAmericanOZen[Deist ... to learn ... to think ... to live ... to laugh ... to share.
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