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Why Darwinian medicine is a dead loss

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In “Darwinian Medicine and Proximate and Evolutionary Explanations,” at Evolution News & Views (June 25, 2011), neurosurgeon Mike Egnor makes a critical distinction between proximate explanations and evolutionary explanations,s they apply to medicine:

Proximate explanations are the description of the process itself. A proximate explanation of type 1 diabetes is that it is caused by lack of insulin. A proximate explanation of Duchenne muscular dystrophy is that it is a recessive X-linked genetic disease that causes muscle degeneration, weakness and death. Males are affected, though females can be carriers. It is caused by a mutation in the dystrophin gene on the X chromosome (Xp21).

As you can see, proximate explanations are what medical researchers would call the scientific explanation for a disease. Proximate explanations are medical science and provide the foundation for all medical treatments.

[ … ]

The difficulty with evolutionary explanations in medicine is:

1) All of the relevant pathophysiology is provided by the proximate explanations, which are the only explanations useful for treatment.

There are other difficulties but that first one is the swish of Occam’s Razor, as far as medicine is concerned.

Takin’ it to the street: You tripped and sprained your ankle. What you need is a speculative history of the sprained ankle in vertebrates … not!

The principle question is, what is evolutionary medicine meant to do, given that it is no use in the normal sense?

Comments
Mung: "I don’t need to get the book and read it. I’ve been interested in the immune system for a while. I have textbooks on immunology. It really is pretty cool." === Agreed, it is pretty kool. The only reason the book is a beautiful read is it's use of illustrations and metaphors for helping the average person appreciate just how brilliantly complex and sophisticated the entire process actually is. Nothing random about it. --- Mung: "But it does start out as a rather stochastic process. The body doesn’t know what sort of pathogen it might encounter so it generates all sorts of “sentries” to be on the lookout." === I would say it would be stochastic or random if the the T-Cells and B-Cells just came out of the bone marrow and went off to wage war and hopefully one or two of them got lucky. However as the book pointed out, they are actually sent to a college of sorts or military academy for specialized training. Their weaponry is ultramodern. High-tech training is mandatory before they take to the field. The T cells will be involved in biological warfare. B cells will be specializing in guided missiles. They get their training for this in the technical colleges of the immune system. Again, very sophisticated and technical and hardly the makings of blind pointless unguided processes. --- Mung: "It’s like the body has a built-in GA." === Yes I believe Genetic algorithms and a host of other sophisticated componants are a work here, even other things we have yet to discover. As you state it is truly amazing.Eocene
June 29, 2011
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I don't need to get the book and read it. I've been interested in the immune system for a while. I have textbooks on immunology. It really is pretty cool. But it does start out as a rather stochastic process. The body doesn't know what sort of pathogen it might encounter so it generates all sorts of "sentries" to be on the lookout. And if one is triggered it is favored over the others and more of it's kind are generated. It's like the body has a built-in GA.Mung
June 29, 2011
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Mung: "You mean they employ an essentially stochastic function with selection?" ==== Hardly, get the book and READ it. Not at all difficult to understand unless worldview is diliberately allowed to stochastically get in the way and fuzzy it for you. *wink*Eocene
June 29, 2011
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An easy way to understand what and how they do it is to read up on your own immune system and how it functions and works when the body is attacked.
You mean they employ an essentially stochastic function with selection?Mung
June 29, 2011
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Mung: "How does a bacterium evolve resistance to an antibiotic?" "How does a population of bacteria evolve resistance to an antibiotic?" === This an easy one. It doesn't evolve anything, it engineers itself using purpose and intent with the genetic informational tools it has in it's possion. An easy way to understand what and how they do it is to read up on your own immune system and how it functions and works when the body is attacked. It re-engineers itself for defensive measures never encountered before and it keeps records of past attacks. EXAMPLE: People around after WWII who not only survived the war, but also the Spanish Influenza. Those survivors today if any, still contain memory cells in their immune system which were engineered way back when. Though it's an older book, "THE BODY VICTORIOUS" [I believe written in the 1980s by Lennart Nilsson, with Jan Lindberg] beautifully illustrated just how sophisticated and engineered our immune system is. The cells just aren't manufactured and sent out to search and destroy, they first get sent to the lymph system to go to school, that is to be specifically engineered with certain weaponry to deal with the specific and unique new invader of the body never encountered before. Memory cells are kept in existance over a life time for the individual who had the experience. Bacteria, though more simple than us, though still extremely complex engineer in similar ways. But by all means find, obtain and read that book. --- Mung: "Any room for equivocation here?" === You bet there is. For education and entertainment value, please read Cornelius Hunter's arguement with hardcore evolutionary diehards who won't own up to anything, especially when they run in packs. http://darwins-god.blogspot.com/2010/02/hopeful-monsters-endless-list-of.html Enjoy!!!Eocene
June 29, 2011
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How does a bacterium evolve resistance to an antibiotic? How does a population of bacteria evolve resistance to an antibiotic? Any room for equivocation here? Does Darwinism predict that either of these will happen? Does Darwin’s account explain why we see antibiotic resistance in bacteria? Does Darwinian evolution offer a clear prediction that bacterial populations will evolve resistance to an environment in which antibiotics are part of the landscape.Mung
June 28, 2011
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Here's that link to the article I forgot to reference above. http://www.newscientist.com/article/dn13839-comment-putting-evolution-theory-into-practice.html?DCMP=ILC-hmts&nsref=news2_head_dn13839Eocene
June 28, 2011
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Elizabeth Liddle: "Darwinian evolution offered a clear prediction/b>, that bacterial populations would evolve resistance to an environment in which antibiotics were part of the landscape." Mung: "This is false. You’ve made a very similar claim in the past and I pointed out why it was false then as well. So why do you persist?" === Perhaps this will put it into perspective as to the reason and motive behind such incessant ideological rantings in the face of real world observation and logic. This article back in May 2008 in New Scientist online journal addressing the same ideological motives as your opponent above. Prof Randolph Nesse is a well known advocate of so-called evolutionary applications medicine was quoted in this article and proving not only how ignorant such a worldview can be as far as deadly consequences, but the last paragraph shows what truly motivates these political agenda pimping shills. Randolph Nesse: " . . progress is being hampered by the fact that many medics still think of the body as a machine designed by an engineer, when in fact it is a "bundle of compromises ... designed to maximise reproduction, not health". So how many here want a doctor with the flawed worldview of your body being nothing more than a bundle of compromises, or one who truly is interested in the science of viewing your amazing construct as designed by an engineer ??? Now notice in the very last paragraph of this article sums up that ultimately it is NOT about the science so much as it's about the ideology and philosophy for directing politics and worldview. New Scientist: "There is no question about the importance of applied evolution. The trouble is, if biologists themselves are only just waking up to how relevant and crucial evolution can be, what hope is there of educating the leaders and policy makers who need to understand and act upon this research? Not much, I fear." So what do leaders and policy makers have to do with science ??? Oh that's right, they don't!Eocene
June 28, 2011
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Elizabeth: One additional thought comes to mind. You said @ 58 that the term “species” is not a relevant or helpful term for bacteria. If that is so, then how could they have been the precursors of any species? At what point does a strain become a species? Because as I see it, if they can't ever create a new species, evolution kinda stops at the bacteria level – correct? Again, thanks for your time. Regards, EJREJR
June 27, 2011
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Elizabeth: Thank you again for taking the time to respond. But I was surprised at a couple of things in your response @43: You stated:
“Micro evolution” (indeed all evolution in some sense) can be described as “a change in allele frequence over time”, and this is exactly what happens when an environment changes, and alleles change in the degree to which they confer reproductive advantage.
Defining evolution as “a change in allele frequence over time” seems totally useless to me. Every single time there is a descendent due to sexual reproduction, this occurs, whether the change is beneficial, neutral, or harmful. So if evolution simply means that descendents will always become slightly different, that is not helpful, and that is NOT what I think most people mean when they use the term “evolution.” So with that definition, if my daughter has dark hair (mine's light brown), she evolved. And since her son has light brown hair, he evolved too – although his hair is just like mine (and this is exactly what has happened in my family). And I have no clue whether hair color produces any kind of reproductive advantage (well, my son-in-law obviously liked dark hair, and I suspect my grandson will eventually find someone who likes light-brown hair, once he learns to talk and walk a bit better!). And yet with all of us evolving, we are still exactly the same species, the same kinds of living thing. So I can't accept "allele frequency change" as a helpful definition of evolution. And so your statement that by using your definition, evolution occurred, does not seem helpful. It seems to me that “evolution” as used by most people would incorporate what I had mentioned @41, in that it is a change that leads to a new kind of living thing, not just one with different hair color or eye color. Also, my understanding about bacterial resistance is this: when there is any kind of mutation during reproduction, it is never the kind that has been seen to produce a new kind of living thing. It's simply a new strain, (as you mentioned @58), and we don't see bacteria developing wings or sonar or anything complex, beyond rather simple changes that make them resistant to an antibiotic. You mention:
Well,there are two parts to evolutionary theory: one is the creation of variance; the second is the selection of beneficial variants. I don’t think allanius, or anyone else here doubts that selection of beneficials take place. The controversy is whether any new, potentially beneficial, alleles are created by mutation alone, or whether somehow they are already either present in some members of a population, or there as “silent” alleles to be “switched on” by some means, when the environment requires it. But you’d have to ask an IDist how they think useful alleles are produced – I don’t know! I think they arise from various mutation mechanisms that occur during reproduction.
My understanding is that bacteria have been “pre-programmed”, if you will, to vary their descendants during reproduction such that the descendants all have slightly different abilities to adapt to changing environments. They always do that, whether in the presence of an antibiotic or not. And that makes a few of them likely to survive an antibiotic treatment, the same as some are more likely to survive with other changes in the environment. And I've read that when some threat such as an antibiotic is present, they can vary more quickly, but the variances are in specific areas and not throughout the entire genome. That tells me the changes are likely NOT truly random, which Darwinian evolution requires, but rather they occur due to some genetic programming already existing in their genome. The fact that some survive doesn't mean much, especially since, as I've read, when these “super” strains combine with normal strains over a period of a few months, they revert to the normal strain. These changes never create a fundamentally new type of bacteria; they are always just a new strain of the same species. I've read Genetic Entropy by John Sanford, where he shows that beneficial mutations that might occur will usually be “shouted down” by the environmental noise, such that there is little evidence that beneficial mutations can propagate rapidly. And I'm not concerned about hair color, or the wing color of moths, or the size of beaks, which although they are changes in allele frequency, those frequencies always go up and down and fluctuate, but none of them gives a unique feature, and they have always been observed to stay within certain limits. So what I'm looking for but haven't seen is concrete evidence of a real new feature that evolved that created a new kind of living thing, not just another color or strain. I've read lots of ID and evolution books, and I've read lots of evidence from the ID side showing that these types of major changes have never happened in bacterial colonies, but I haven't seen any refutation of what the ID side claims (specifically, books by Behe: The Edge of Evolution and by Meyer: Signature in the Cell). So until I can see real scientific evidence showing that macro evolution can really occur, I think I have to vote with the ID camp. From my layman's view, it seems that the "science" behind evolution is more on theoretical paper arguments than in the actual physical evidence, while on the other hand, the ID side seems to be squarely and firmly centered on the scientific evidence. But... I would love to see some evidence, for example, of a true beneficial mutation. And not sickle cell anemia, please. My daughter's sister-in-law unfortunately has that disease and will succomb to it in a few more years. I have never understood how people could claim this fatal mutation as an example of how beneficial mutations are upward improvements supporting evolutionary theory, despite providing some certain benefit against malaria. Regards, EJREJR
June 27, 2011
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Because Darwinian theory says that if you assault a population with a toxin and fail to kill it, the remaining population will be biased in favour of the resistant members, and subsequent generations will be resistant to the toxin.
Again, that is not true. Darwinian theory does not predict that the members who survived did so because they were resistant. It could in fact be that case that they survived because they were not subjected to the toxin at all. That's why you "finish the course," as you call it. It makes no sense to "finish the course" if the course doesn't kill the resistant bacteria.Mung
June 27, 2011
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Elizabeth Liddle:
So allanius is correct, but that doesn’t mean that no evolution took place! By the above definition, it did.
But you don't equivocate, do you.Mung
June 27, 2011
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Mung, you are stuck in the rut of thinking everything is about proving Darwinism right or wrong. It isn’t.
You're mistaken Elizabeth. Modern evolutionary theories are incoherent. As in not even wrong. Darwinism isn't falsifiable. It's basic tenet is a tautology. It would be a waste of my time to try to prove it's wrong.
If it could be demonstrated that any complex organ existed which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down. But I can find out no such case.
If you want to believe, like Darwin, I cannot stop you. But it's not on me to disprove the theory. You need demonstrate that Darwinian mutation/selection can actually bring about the effects attributed to it's power. Good luck.Mung
June 27, 2011
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Elizabeth, I KNOW YOU are sold on the whole antibiotic thing, but I just can't buy it.bornagain77
June 27, 2011
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BTW, made some enquiries about the concept of "species" with regard to bacteria. It seems that Lynn Margulis agrees with me, that "species" is not a relevant or helpful term for bacteria. http://www.astrobio.net/interview/2108/bacteria-dont-have-species In that case, I'd really like to know what Jonathan Wells meant when he claimed that even though bacterial populations evolve antibiotic resistance, no new "species" have been observed. It seems to me that that is a fairly meaningless claim. What is important is that new strains evolve and, unfortunately flourish, in response to widespread antibiotic use. That doesn't prove that Darwinian evolution can account for the whole variety of life on earth, but it a) confirms that the principle works and b) stands as an example of how Darwinian principles are relevant to clinical practice.Elizabeth Liddle
June 27, 2011
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Elizabeth, your in that whole psychology thing aren't you??? Do you think I need to be 'deprogrammed' so that I can be a faithful Darwinbot once again??? 1984 Apple's Macintosh Commercial - video http://www.youtube.com/watch?v=OYecfV3ubP8bornagain77
June 27, 2011
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Elizabeth these videos are not helping either: Powering the Cell: Mitochondria - video http://www.youtube.com/watch?v=RrS2uROUjK4 Molecular Biology Animations - Demo Reel http://www.metacafe.com/w/5915291/bornagain77
June 27, 2011
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Elizabeth, if the flagellum is too hard for you, perhaps you could 'lay hands' on your flask and evolve me the 'simpler' ATP synthase so as to restore me to the fold of the Darwinian faithful: Evolution vs ATP Synthase - Molecular Machine - video http://www.metacafe.com/watch/4012706 The ATP Synthase Enzyme - exquisite motor necessary for first life - video http://www.youtube.com/watch?v=W3KxU63gcF4 ATP synthase: majestic molecular machine made by a mastermind - November 2010 http://creation.com/atp-synthase Fine-Tuning Found in Life’s Rotary Engine - August 2010 Excerpt: ATP synthases are among the most abundant and important proteins in living cells. These rotating nano-machines produce the central chemical form of cellular energy currency, ATP (adenosine triphosphate), which is used to meet the energy needs of cells. For example, human adults synthesize up to 75 kg (165 lbs.) of ATP each day under resting conditions and need a lot more to keep pace with energy needs during strenuous exercise or work. The turbine of the ATP synthase is the rotor element, called the c-ring. This ring is 63 A [Angstroms] in diameter (6.3 nm, or 6.3 millionths of a millimeter) and completes over 500 rotations per second during ATP production. 500 rotations per second amounts to, in the terminology of more familiar motors, some 30,000 RPM. Since three ATP molecules are synthesized for each rotation, one of these motors can generate just short of 100,000 ATP per minute – and your body has quadrillions of them working all your life, even in your sleep. http://www.creationsafaris.com/crev201008.htm#20100804a =================bornagain77
June 27, 2011
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Well, you could try checking out some of those Lenski papers, ba77, and see whether Scott Minnich is really correct when he says that when a beneficial mutation appears, it is always "at a cost" and compensatory mutations are never enough for it to reach the fitness of its ancestral population. I'm pretty sure you will find they are wrong, so that should keep your spirits up until I manage to evolve a bacterial flagellum for you :) OK, better get back to my lab....Elizabeth Liddle
June 27, 2011
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Dang it Elizabeth you state; 'In the mean time, you’ll have to make do with micro-evolution, which clearly occurs, because it’s been observed, and maybe speciation, on a small scale, as well.' Man I'm really weak in my blind devotion to Darwin here Elizabeth, you see those doggone IDists have come along and said that ALL those micro-evolutionary events are occurring at a loss of functional information,,, moreover they attack my faith again by saying that all sub-speciation events are the result of reproductive isolation brought about by loss of information.,,, I relly need me a 'miracle' Elizabeth or I might go back to my heathen IDists waysbornagain77
June 27, 2011
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Michael Behe Hasn't Been Refuted on the Flagellum - March 2011 http://www.evolutionnews.org/2011/03/michael_behe_hasnt_been_refute044801.html Bacterial Flagella: A Paradigm for Design – Scott Minnich – Video http://www.vimeo.com/9032112 Flagellum - Sean D. Pitman, M.D. http://www.detectingdesign.com/flagellum.html The Bacterial Flagellum – Truly An Engineering Marvel! - December 2010 https://uncommondescent.com/intelligent-design/the-bacterial-flagellum-truly-an-engineering-marvel/bornagain77
June 27, 2011
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And though I would be impressed by the 'evolution' of ANY molecular machine by neo-Darwinian processes, I would be particularly interested if you could falsify Behe on the flagellum by 'evolving' one of those: Bacterial Flagellum - A Sheer Wonder Of Intelligent Design - video http://www.metacafe.com/watch/3994630 Bacterial Flagellum: Visualizing the Complete Machine In Situ Excerpt: Electron tomography of frozen-hydrated bacteria, combined with single particle averaging, has produced stunning images of the intact bacterial flagellum, revealing features of the rotor, stator and export apparatus. http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VRT-4M8WTCF-K&_user=10&_coverDate=11%2F07%2F2006&_rdoc=1&_fmt=full&_orig=search&_cdi=6243&_sort=d&_docanchor=&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=8d7e0ad266148c9d917cf0c2a9d12e82&artImgPref=F Electron Microscope Photograph of Flagellum Hook-Basal Body http://www.skeptic.com/eskeptic/08-08-20images/figure03.jpg Biologist Howard Berg at Harvard calls the Bacterial Flagellum “the most efficient machine in the universe." The flagellum has steadfastly resisted all attempts to elucidate its plausible origination by Darwinian processes, much less has anyone ever actually evolved a flagellum from scratch in the laboratory; Stephen Meyer - T3SS Derived From Bacterial Flagellum (Successful ID Prediction) - video http://www.youtube.com/watch?v=3c-EAzJ8_4U Genetic Entropy Refutation of Nick Matzke's TTSS (type III secretion system) to Flagellum Evolutionary Narrative: Excerpt: Comparative genomic analysis show that flagellar genes have been differentially lost in endosymbiotic bacteria of insects. Only proteins involved in protein export within the flagella assembly pathway (type III secretion system and the basal-body) have been kept... http://mbe.oxfordjournals.org/cgi/content/abstract/msn153v1 Phylogenetic Analyses of the Constituents of Type III Protein Secretion Systems Excerpt: We suggest that the flagellar apparatus was the evolutionary precursor of Type III protein secretion systems. http://www.horizonpress.com/jmmb/v2/v2n2/02.pdf "One fact in favour of the flagellum-first view is that bacteria would have needed propulsion before they needed T3SSs, which are used to attack cells that evolved later than bacteria. Also, flagella are found in a more diverse range of bacterial species than T3SSs. ‘The most parsimonious explanation is that the T3SS arose later," Howard Ochman - Biochemist - New Scientist (Feb 16, 2008) Michael Behe on Falsifying Intelligent Design - video http://www.youtube.com/watch?v=N8jXXJN4o_A Genetic analysis of coordinate flagellar and type III - Scott Minnich and Stephen Meyer Molecular machines display a key signature or hallmark of design, namely, irreducible complexity. In all irreducibly complex systems in which the cause of the system is known by experience or observation, intelligent design or engineering played a role the origin of the system. http://www.discovery.org/scripts/viewDB/filesDB-download.php?id=389bornagain77
June 27, 2011
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ba77:
Elizabeth you seem to have this figured out (ha); but I’m still kind of a ‘shaky convert’,,, do you mind evolving just a single molecular machine for me so as to ease my doubts in the almighty power of evolution???
I'll do my best, ba77 :) In the mean time, you'll have to make do with micro-evolution, which clearly occurs, because it's been observed, and maybe speciation, on a small scale, as well.Elizabeth Liddle
June 27, 2011
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Elizabeth you seem to have this figured out (ha); but I'm still kind of a 'shaky convert',,, do you mind evolving just a single molecular machine for me so as to ease my doubts in the almighty power of evolution??? Astonishingly, actual motors, which far surpass man-made motors in 'engineering parameters', are now being found inside 'simple cells'. Articles and Videos on Molecular Motors http://docs.google.com/Doc?docid=0AYmaSrBPNEmGZGM4ejY3d3pfMzlkNjYydmRkZw&hl=en Michael Behe - Life Reeks Of Design - 2010 - video http://www.metacafe.com/watch/5066181 And in spite of the fact of finding molecular motors permeating the simplest of bacterial life, there are no detailed Darwinian accounts for the evolution of even one such motor or system. "There are no detailed Darwinian accounts for the evolution of any fundamental biochemical or cellular system only a variety of wishful speculations. It is remarkable that Darwinism is accepted as a satisfactory explanation of such a vast subject." James Shapiro - Molecular Biologist The following expert doesn't even hide his very unscientific preconceived philosophical bias against intelligent design,,, ‘We should reject, as a matter of principle, the substitution of intelligent design for the dialogue of chance and necessity,,, Yet at the same time the same expert readily admits that neo-Darwinism has ZERO evidence for the chance and necessity of material processes producing any cellular system whatsoever,,, ,,,we must concede that there are presently no detailed Darwinian accounts of the evolution of any biochemical or cellular system, only a variety of wishful speculations.’ Franklin M. Harold,* 2001. The way of the cell: molecules, organisms and the order of life, Oxford University Press, New York, p. 205. *Professor Emeritus of Biochemistry, Colorado State University, USA Michael Behe - No Scientific Literature For Evolution of Any Irreducibly Complex Molecular Machines http://www.metacafe.com/watch/5302950/ “The response I have received from repeating Behe's claim about the evolutionary literature, which simply brings out the point being made implicitly by many others, such as Chris Dutton and so on, is that I obviously have not read the right books. There are, I am sure, evolutionists who have described how the transitions in question could have occurred.” And he continues, “When I ask in which books I can find these discussions, however, I either get no answer or else some titles that, upon examination, do not, in fact, contain the promised accounts. That such accounts exist seems to be something that is widely known, but I have yet to encounter anyone who knows where they exist.” David Ray Griffin - retired professor of philosophy of religion and theology “The First Rule of Adaptive Evolution”: Break or blunt any functional coded element whose loss would yield a net fitness gain - Michael Behe - December 2010 Excerpt: In its most recent issue The Quarterly Review of Biology has published a review by myself of laboratory evolution experiments of microbes going back four decades.,,, The gist of the paper is that so far the overwhelming number of adaptive (that is, helpful) mutations seen in laboratory evolution experiments are either loss or modification of function. Of course we had already known that the great majority of mutations that have a visible effect on an organism are deleterious. Now, surprisingly, it seems that even the great majority of helpful mutations degrade the genome to a greater or lesser extent.,,, I dub it “The First Rule of Adaptive Evolution”: Break or blunt any functional coded element whose loss would yield a net fitness gain.(that is a net 'fitness gain' within a 'stressed' environment i.e. remove the stress from the environment and the parent strain is always more 'fit') http://behe.uncommondescent.com/2010/12/the-first-rule-of-adaptive-evolution/ Michael Behe talks about the preceding paper on this podcast: Michael Behe: Challenging Darwin, One Peer-Reviewed Paper at a Time - December 2010 http://intelligentdesign.podomatic.com/player/web/2010-12-23T11_53_46-08_00 What I find very persuasive, to the suggestion that the universe was designed with life in mind, is that physicists find many processes in a cell operate at the 'near optimal' capacities allowed in any physical system: William Bialek - Professor Of Physics - Princeton University: Excerpt: "A central theme in my research is an appreciation for how well things “work” in biological systems. It is, after all, some notion of functional behavior that distinguishes life from inanimate matter, and it is a challenge to quantify this functionality in a language that parallels our characterization of other physical systems. Strikingly, when we do this (and there are not so many cases where it has been done!), the performance of biological systems often approaches some limits set by basic physical principles. While it is popular to view biological mechanisms as an historical record of evolutionary and developmental compromises, these observations on functional performance point toward a very different view of life as having selected a set of near optimal mechanisms for its most crucial tasks.,,,The idea of performance near the physical limits crosses many levels of biological organization, from single molecules to cells to perception and learning in the brain,,,," http://www.princeton.edu/~wbialek/wbialek.htmlbornagain77
June 27, 2011
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What "fitness test"? ba77? I see a video that makes errors. Also, Scott Minnich claims that resistant bacteria "never regain the fitness of the original", even though he accepts that "compensatory mutations" occur. Apart from the fact that he is comparing the "fitness" of the evolved resistant strain with the "fitness" of the ancestral strain in an environment without antibiotics (which would be like comparing the "fitness" of a cow and a whale in a field, and claiming that the whale had never "regained" the fitness it lost when it lost its back legs and exchanged them for "compensatory" fins), no reference is given for this claim. It is possibly true - that resistant bacteria, which are hugely "successful" and therefore a major threat to people, are "less fit" than non-resistant bacteria when placed in an antibiotic-free environment, but it may not be. I don't know. I don't suppose anyone has tested it because it's completely irrelevant to the problem of antibiotic resistance. Or, indeed,to evolutionary theory. "Adaptation" is the process by which populations become best fitted, by Darwinian mechanisms that no-one disputes, it seems (not the people in that video anyway) to the current environment. Nobody expects Darwinian theory to explain why whales are unfit when placed in a field, nor cows unfit when placed in the ocean. Both are well-fitted to their environment, which was Darwin's entire point.Elizabeth Liddle
June 27, 2011
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Also, the guy with the test tube makes an error. He says, when he replaces the resistant bacteria in an environment with the original that he has "removed selection". He hasn't. He has changed the environment, so that now, the resistance allele is deleterious. Obviously, every time you change the environment, you will tend to get a change in allele frequency. In this experimental set up, the frequency oscillates depending on the environment. However, let the resistant strain evolve in an environment in which the ancestral non-resistant strain are not present, and fitness is likely to increase. This is what Lenski's experiments showed - that given an ancestral population in a given environment, fitness will tend to increase, relative to the ancestral population. But you have to control the environment - if you change that too, then you will get a meaningless answer, as in this video.Elizabeth Liddle
June 27, 2011
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Elizabeth, pass the test then you will have a legitimate 'scientific' leg to stand on.bornagain77
June 27, 2011
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ba77: your video simply confirms what I am saying - that Darwinian evolution results in bacterial resistance. What the video also says is that this "doesn't go far enough" because it doesn't account for "new species". Well, I'm not, here, saying it does (though I think it does!) - I'm merely pointing out that Darwinian evolution is a good model for bacterial resistance, and directly informs clinical practice. Re speciation: it has, in fact, been observed, whatever Jonathan Wells claims, in that non-interbreeding descendent populations from a single ancestral population have been observed. However, obviously you won't see this in bacterial populations because bacteria don't actually interbreed. In fact, tbh, I don't know how "species" is defined as a concept in regard to populations that only reproduce by cloning. And, in any case, "speciation" doesn't mean that daughter species from a single ancestral population are a different "species" from ancestral population. It's a mostly meaningless concept because that ancestral population no longer exists. However, what is probably true is that when a population speciates, resulting in two non-interbreeding population, one of those two may tend to remain more similar to the ancestral population than the other, and, theoretically at least, could interbreed with it if it could be thawed out and reanimated (you could at least try this out with sexually reproducing plants). However, if, for example, modern dogs end up speciating (as they almost have), it won't make either the chihuahua lineage, or the Great Dane lineage "not dogs". In both lineages (from the ancestral wild dog) what we would be observing (if we had the data) would be changes in allele frequency in the population over time. It's just that you'd have to plot the frequency changes twice, once for each lineage, and you'd get two lineages of changes. This is why the micro-but not macro- argument is flawed. Yes, other factors affect whether a population splits or not (i.e. whether speciation occurs, or simply "vertical" evolution) but for any one lineage, the "micro" definition of evolution will apply.Elizabeth Liddle
June 27, 2011
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Is Antibiotic Resistance evidence for evolution? – ‘The Fitness Test’ – video http://www.metacafe.com/watch/3995248bornagain77
June 27, 2011
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Hi EJR!
In #4 and #8, you explain how bacteria evolve due to antibiotics. I think I understand your explanation, but it doesn’t seem to explain what actually happens. Allanius (#35) explains that there is no real evolution, that there were already different strains before the antibiotic was administered, which to me makes more sense.
It is quite possible, indeed probable, that before the antibiotic was administered, some bacteria were already resistant, i.e. had some allele or alleles that meant that they had better-than-average resistance to penicillin. However, prior to the introduction of penicillin these alleles were approximately "neutral" in effect - i.e. they conferred no reproductive advantage, and so their prevalence in the bacterial population remained low. However, once the population is in an environment containing penicillin, those resistant alleles now become highly advantageous, and so their prevalence in subsequent generations (descendent populations) becomes very much higher. "Micro evolution" (indeed all evolution in some sense) can be described as "a change in allele frequence over time", and this is exactly what happens when an environment changes, and alleles change in the degree to which they confer reproductive advantage. So allanius is correct, but that doesn't mean that no evolution took place! By the above definition, it did. However, what happens next is that if penicillin continues to be used, and the surviving bacteria move to new hosts and become endemic in the human population, the danger is that that the frequency of resistant alleles in that endemic population becomes higher and higher, and with repeated penicillin treatments, or other treatments, new alleles from time to time emerge as well, and as well as the antibiotics effectively "filtering in" those alleles that already existed and happened to confer antibiotic resistance, we now have strong "selective pressure" on any new alleles that might work even better. This is why it is important to find out, when we meet a multiply resistant bacteria, to find out what, in its genome, is conferring the resistance, and how. That informs development of new drugs that can attack it where it is weakest.
So… are you saying that, immediately before the antibiotic is ingested, there were no resistant bacteria, but then they somehow instantly evolved due to interaction with the antibiotic so that some would survive?? If you are NOT saying this, then how do the bacteria evolve any resistance that wasn’t there?
Well,there are two parts to evolutionary theory: one is the creation of variance; the second is the selection of beneficial variants. I don't think allanius, or anyone else here doubts that selection of beneficials take place. The controversy is whether any new, potentially beneficial, alleles are created by mutation alone, or whether somehow they are already either present in some members of a population, or there as "silent" alleles to be "switched on" by some means, when the environment requires it. But you'd have to ask an IDist how they think useful alleles are produced - I don't know! I think they arise from various mutation mechanisms that occur during reproduction.
If none were resistant to the antibiotic, they would all be killed, wouldn’t they? It seems that evolution, in the way you think about it, didn’t actually do anything, but rather the antibiotics just selected for a variant that was naturally — and already — there, well before the antibiotic was introduced.
Yes. Probably several variants that conferred resistance to varying degrees. However, that doesn't mean that subsequent new variants, conferring even greater resistance won't appear, and, of course, if they do, because the environment now favours such alleles (renders them beneficial) they will tend to propagate rapidly through the population.
My understanding matches what I think Allanius explained, that the bacteria have been pre-programmed to produce descendants that are continually different in subtle ways for the purposes of increasing the odds of some offspring remaining after any environmental threat. And these changes are ALWAYS restricted in some way, so that no matter how many generations occur, and no matter how many variations occur, they are always the same species. (It seems to me, from what I’ve read, that the bacteria make changes in MICRO ways that never change the basic kind of bacteria, but these changes are never MACRO in a way that creates a new bacteria.)
Well, I'm not sure how this is supposed to work. You'd have to ask someone who believes it! But I do think it's likely that mutational mechanisms themselves have evolved, so that the kinds of variants that tend to appear during replication are biased in favour of the kinds of variants that may give rise to mostly near neutral, rather than disastrous, mutations, some of which will tend to be beneficial in some circs. Those kinds of mechanisms would render populations more robust, and therefore tend to be selected at population level (populations with healthy variance-producing mechanisms will have less chance of going extinct when they meet a new hostile environment).
So, if you could, please explain for me how it is that the antibiotic causes evolution (rather than simply eliminating most varieties, but ignoring those that had already been modified before the bacteria ever saw the antibiotic). Thanks, EJR
Hope that helps at least in understanding the "Darwinian" position! The IDists will have to help out with the alternative :)Elizabeth Liddle
June 27, 2011
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