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Member Posts: 3945 From: Duluth, Minnesota, U.S. (West end of Lake Superior) Joined: Member Rating: 10.0 |
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Author | Topic: What if creationism did get into the science class | |||||||||||||||||||||||
Quetzal Member (Idle past 5903 days) Posts: 3228 Joined: |
TC: While you're considering your response to Moose, please consider that you constantly harp on creation science being scientific. You have also stated in post #5 "In my opinion, there would be some reasons it would go down quick, but it would also depend on whether your going to stick religion in there along with the science of creationism." (emphasis added).
TC, creation science is by definition religious. It has several a priori religious/supernatural assumptions that must be accepted for creation science to exist in the first place: 1. A creator of some type exists. In creationism, this is generally some form of diety. Creation "scientists" often try and obfuscate the identity of the creator by calling it a Designer, or whatever. There is no semantic difference between the two concepts. Even arguing the LGM hypothesis ("little green man") leads to a problem of reduction: who created the LGM? and so on. Ultimately, the creator MUST be supernatural for creationism and its child creation science to exist. 2. After accepting the unprovable assumption of the existence of a supernatural creator, creation "science" requires acceptance of the premise that this creator intervenes (or did so at least once) regularly in its creation for reasons of its own - again with no mechanism or evidence to back the claim. Since science, by definition, cannot comment on supernatural phenomena, creation science is an oxymoron. Teaching it in any other venue other than a philosophy course would be anathema. Giving it equal billing with evolutionary biology, or even high school biology, is granting it more legitimacy than it has earned. By all means teach controversies and point up the gaps in scientific knowledge, but don't permit religous dogma or the supernatural to intrude into science class. Separating Religious Fundamentalist "Science" from Science[/URL], by Tim Berra. Directly related to Moose's OP, here's a quote from the article: quote: I LIKE this guy. [This message has been edited by Quetzal, 04-30-2002]
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Quetzal Member (Idle past 5903 days) Posts: 3228 Joined: |
quote: Brad: We are, for the first, and possibly only, time in history in complete agreement.
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Quetzal Member (Idle past 5903 days) Posts: 3228 Joined: |
quote: Hey Cobra! No form of Creation should be taught in a science classroom - including the current forms of ID. No matter how you dress it up, ID as pushed by the likes of Dembski, Behe, and others of that ilk, is nothing more than biblical literalism hidden away in pseudo-scientific jargon to confuse the gullible. I will grant that if (and this is a mighty big if) ID EVER comes up with anything resembling evidence for design or a designer beyond the usual god-of-the-gaps or argument from incredulity, then MAYBE it could be considered for inclusion in a science curriculum. As it stands, they have NOTHING. ZERO. ZILCH. NADA. ZIP. I don't particularly care how many scientific illiterates want ID treated on equal footing with evolution. Argumentum ad populum is just another fallacy - and since that's the best ID can come up with... BTW: I'd love to see your "evidence against evolution" that should be taught in science class. What "evidence" do you think you've got?
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Quetzal Member (Idle past 5903 days) Posts: 3228 Joined: |
Very cute. Now do you have anything substantive to add? For example, at least ONE piece of verifiable data or ONE single observation that can be better explained by ID than by ToE? God-of-the-gaps, argument from incredulity, argument from authority, and argumentum ad populum do NOT constitute evidence.
Also, please provide YOUR particular version of punk-eq. It appears you have erected some kind of saltationist strawman, but you haven't really provided any details on the model you claim to argue against. Final note: I don't need to provide evidence against ID. ID needs to provide positive evidence for their theory. I (and others) have presented you multiple converging lines of evidence for evolution. The least you could do is return the favor. this post[/URL] would be especially welcome. [This message has been edited by Quetzal, 05-31-2002]
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Quetzal Member (Idle past 5903 days) Posts: 3228 Joined: |
Hi Philip (wow, near real-time). I'll compose an answer to your rebuttal on the other thread. Meanwhile:
quote: Got it. I'll respond in the other thread.
quote: I know you don't support punk-eq. You appeared to be arguing against some odd version of it in the post to which I responded. I merely asked your take on the details of the particular version you were against, 'cause it didn't sound like any PE flavor I'd ever encountered. Can't refute your assertion without understanding what it is.
quote: We are in total agreement here.
quote: Yep. Way too broad to be scientific. And yes, the Little Green Man hypothesis is one of the potential "designers". 'Course that merely begs the question "who or what created the Little Green Men?".
quote: Anti-ID is suspicious? Don't you mean ID? My personal anti-ID stance rests pretty much on the utter lack of positive evidence for ID. I'm not against ANY theory (well, scientific theory [This message has been edited by Philip, 05-31-2002][/B][/QUOTE]
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Quetzal Member (Idle past 5903 days) Posts: 3228 Joined: |
quote: I concede your point. However, the difficulty is that Dembski, Behe, et al are primarily associated with an organization — in fact that’s about the only place they submit articles — that IS 100% YEC/biblical literalist. The Discovery Institute has as its principle tenets a stated belief in the inerrancy of the bible. (I think others have provided links to their doctrine.) Separating the primary researchers from the stated goals and philosophy of the organization to which they are attached is problematic, I’d say. Hey, it could happen. My partner, for instance, teaches biology at a Baptist-run college, and he is FAAAARR from a believer — he’s one of the foremost evolutionary biologists in Nicaragua. I won’t call ‘em literalists if you don’t want me to — but they certainly expend an inordinate amount of time on the subject.
quote: That’s a valid question. Actually, there are probably things that would convince me that at least some elements of the ID theory have merit. Remember, they don’t have to prove the whole thing up front — even the ToE has been substantially revised over the last 150 years as new evidence is discovered. They do have to come up with some compelling inferences based on actual physical observations. One example would be to show experimentally that directed evolution can happen. They could use Drosophila for example — one of the best mapped and studied genomes in the world — and show (for ex.) genotype changes within an individual as an adaptation to changed environmental conditions that wasn’t directly related to either mutation or wasn’t already present as a recessive within the population. IOW, that an individual could change its genotype because it wanted or needed to. Other experiments could probably be designed to show how the anthropic principle operates at the ecosystem level. Yet a third possibility (and one I’ve asked for repeatedly from Idists) is a listing of the basic observations from nature that provide the foundation for ID. I listed a few specific examples from the ToE in another post drawn from coevolution, biogeography, and genetics that provide good evidence that the predictions of evolutionary theory fit well. I’d love to see the same thing from ID. So yeah, I can be convinced. Where the argument from incredulity and designer-of-the-gaps keeps creeping in is that instead of trying to provide evidence for ID, the proponents keep trying to find places they can attack the ToE. It don’t work that way.
quote: See above.
quote: This is where I have my biggest problem with ID. Rather than developing the theory as a scientific one, based on evidence, they’ve gone straight from developing an untested hypothesis to political pressure designed to insure it’s taught in public school. They skipped a major step: developing the observational foundation. Right now, all ID has is anti-evolution rhetoric. We want to teach this in schools? I don’t think so.
quote: I agree with you. A lot of textbook publishers — especially for high school — are capitalist scum OTOH, I don’t agree that teaching creationism or ID is valid UNTIL there is compelling evidence for it — as exclusionary of ToE. It isn’t intellectual freedom, it’s science. Nobody teaches geocentrism, because there is compelling evidence for heliocentrism. Even within evolutionary theory, nobody teaches orthogenesis (linear evolution where C supplants B supplants A in the evolutionary sequence ABC), or lamarckism (inheritance of acquired traits — which is itself interesting because this CAN happen at the prokaryote level with gene swapping), etc. These concepts have no evidence, or have huge amounts of evidence against them. Even hypotheses that are based on at least some evidence if it’s open to interpretation aren’t treated in high-school courses (such as species sorting), or even freshman-level biology courses in college. You don’t start seeing these until upper- or even graduate-level courses — where students have a reasonable grounding in the science behind them to judge their merit. As far as this applies to creationism, I know of at least one mainstream college that teaches the controversy — UC Fullerton has an upper-level course in the subject. High school ain’t the place.
quote: I would have to say that your evidence against evolution is pretty weak. There are a lot of transitional forms in the fossil record. Fish-amphibian, amphibian-reptile, reptile-mammal, etc. I will admit, however, that they way these are presented in a lot of basic courses needs to be re-done. OTOH, how many high school students do you think have enough grounding in genetics to even understand pseudogenes and why they’re important? How many students do you feel could even understand irreducible complexity and the arguments for and against it? You’re asking a lot.
quote: I’ve never seen abiogenesis treated as anything more than a theory in a high-school textbook. Most of them don’t even bring it up. And no, OOL doesn’t provide any positive evidence for ID — yeah, the whole Idist argument is both argument from incredulity (science doesn’t yet understand how it happened, therefore designer-did-it) and god-of-the-gaps (science hasn’t shown how specifically life arose from chemistry, therefore the only alternative is goddidit).
quote: a.) How is it obviously superior? On the one hand, you have huge amounts of positive evidence and multiple converging lines of evidence that anyone can go out into the woods or a road cut (for geology/paleontology) just about anywhere in the world and, armed with a little knowledge, can see for themselves. On the other, you have an old, multiply translated book from a single one of the many religions humans are prey to. Or you have someone saying, I don’t know or understand it, therefore goddidit. Or you have someone saying, essentially, I don’t have any evidence — just take my word for it. Hmmm, wonder which one we should teach b.) I fully concur we need better textbooks. On the other hand, at least we’re not stuck with lysenkoism or an official state-sanctioned theory. I’d like to see genuine biologists edit or at least fully review biology texts. Unfortunately, most of them appear pretty busy. An error, IMO. If you ever get a chance, check out Futuyma’s Evolutionary Biology text — one of the best in the business, IMO. This quality is what we should be striving for at all levels. c.) I refer to my points above — how many students do you think have enough background in either theology OR biology to realistically evaluate a two-paradigm approach? Especially since the only impetus for one of them resides solely in a fundamentalist Protestant approach to Christianity. Should we also include all of the other religions’ creation myths? Won’t be a lot of room in the text or time in the year to cover much science — which is the whole point of science class. This is all a relatively new phenomenon. IIRC, my high school biology text (admittedly I shared a classroom with Homo erectus quote: I beg to differ. In the first place, the so-called Santorum amendment was a Sense of the Senate, hence a political polemic, not law. In the second, Santorum’s knowledge of science is nothing short of abysmal. Take a look at my post shredding his premises (it was on one of the thread ksc trashed, but should still be there. I can repost it if you’re interested). And I’ve already voiced my objection to argumentum ad populum.
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Quetzal Member (Idle past 5903 days) Posts: 3228 Joined: |
quote: I stand corrected. I confused DI/CRSC with ICR in that post — not hard to do when they often appear joined at the hip — but I agree CRSC is not an inerrancy org.
quote: True, it would not provide conclusive evidence for design. However, just as the tight mutualistic relationship between the ant (Pseudomermex) and the bulls horn acacia (Acacia colensii) provides supporting evidence for coevolution, directed evolution would provide supporting evidence for design. Any major scientific theory like evolution needs evidence from multiple converging lines. DI needs to start small and accrete evidence like any other theory.
quote: The anthropic principle is at the heart of Denton’s Nature’s Destiny argument. You would need to show that a given ecosystem, for example, is only capable of evolving into its current form — with all the myriad interacting pieces — by design to the exclusion of the standard evolutionary paradigm.
quote: I wish it did. Behe’s entire book is a god/designer of the gaps argument against evolution. Nowhere in the book does it provide any positive evidence for design. Behe merely states that a particular structure is irreducibly complex because evolutionary biology has not shown how it can form. For example, in his argument concerning bacterial flagella, he states Even though we are told that all biology must be seen through the lens of evolution, no scientist has ever published a model to account for the gradual evolution of this extraordinary molecular machine. (pg 72). A quick check of pubmed (try evolution flagella) yields 101 articles with titles like Sequencing of flagellin genes from Natrialba magadii provides new insight into evolutionary aspects of archaeal flagellins.
quote: And yet this is precisely what Behe does! See my quote above, and discussion below.
quote: That’s the point, Cobra. Behe manifestly DID NOT provide any reasons. He invented a term based on a Paley’s-watch-as-mousetrap analogy, then spent thousands of words attempting to show that this subjective and unquantifiable term actually had some basis in reality. To be honest, it’s not a bad approach. The only problem is, his examples are all false! From flagella to hemoglobin to blood clotting, microbiologists and biochemists have whittled away at his examples until he’s left with one type (the rotor) of eubacterial flagella (out of three distinct types) as the only example that hasn’t been completely falsified. And even then, with bacterial genomes being sequenced at the rate of about one a month, the wide variance microbiologists are finding in the number of basal rings on the flagella is tearing the whole idea apart. For instance, in E. coli there are four rings, in Bacillus subtilis two rings, and in Caulobacter crescentus five rings. I can easily imagine a scenario where a "primitive bacteria" might have one ring, and then you have a flagellum with two rings, then three, and so on. This is "gradual, step-by-step" evolution, which is the absolute opposite of Behe's argument. Moreover, this gradual increase could easily happen through things like gene duplication, or a simple mutation in the DNA sequence which would then code for a different amino acid causing two proteins to bind together into a novel structure, etc.
quote: I’m not arguing science by concensus. At this point in the development of evolutionary biology, I’d suggest that the evidence would have to be pretty compelling. However, the point is the IDists have yet to produce ANY evidence. If somehow ID became accepted as at least a reasonable second explanation — with lots of evidence — then the entire question becomes moot.
quote: Actually, if that was in fact what the textbook said, I agree with you — I’d object as well. There really needs to be some good reviews/editing done by real scientists.
quote: I think this is the heart of the creationists’ problem with evolution. It is fundamentally a religious issue. The strange thing is, it is a baseless paranoia. I can think of a lot of very good scientists who are also Christians (and even one or two Moslems and Hindus). They don’t seem to have been overly effected by the indoctrination you’re so worried about. In fact, most of the atheists I know and/or correspond with have stated that their conversion came first, then they discovered science. Most of them came from Christian families, especially Protestant Christian, and were thoroughly indoctrinated from the time they could talk into the Christian world-view. Certainly with your insistence that ID isn’t religiously-based, what possible conversion crisis could it’s putative competing theory — evolutionary theory — cause? If ID is not religious, teaching it in school should cause as much problem with religious conversion as straight evolution, right? You’re revealing more of the truth about ID than you’d like with this assertion. Personally, I try and divorce science completely from religion. I never (unlike Dawkins, for instance) insist that evolution disproves God. OTOH, I try to make it clear that the Christian God — or any other deity or supernatural entity — is not required to explain the diversity of life. Evolution explains things quite nicely without even referring (pro- or con-) to the supernatural. Scientifically, I have to maintain that separation to be consistent with my strong stand that science has no ability — or right - to address questions of the supernatural. Philosophically is another issue. quote: Thanks! You don't do half bad yourself for a creationist. quote: To be honest, I’d probably agree with them, although not for the same reasons. It’s hard to argue against the evidence for something when there isn’t any
quote: Not until the IDists come up with positive evidence for ID. Trying to poke holes in the ToE isn’t going to cut it.
quote: True, however the existence of intermediates AT ALL leads to (using Philip’s favorite term) a parsimonious conclusion that other intermediates are simply yet-to-be-discovered. There are quite a few modern organisms that have no obvious direct ancestor in the fossil record. That doesn’t imply they were created last week. It just implies that we haven’t yet found them, given the rarity of fossilization and the relative paucity of fossils actually found. I would have no problem describing that issue in a textbook — even for high school.
quote: Okay, what are the implications of the existence of pseudogenes?
quote: Yeah? So how do you go about explaining to a high school student how gene duplication in primitive jawless fish can lead to duplication of Alpha hemoglobin into the Alpha, Beta, Delta, and Gamma hemoglobin molecules in modern mammals refutes Behe’s irreducible complexity? Or how E. coli growing on sugars that result in catabolite repression or amino acids that feed into glycolysis causes them to undergo a metabolic switch associated with the production and utilization of acetate. As they divide exponentially, the E. coli excrete acetate via the phosphotransacetylase-acetate kinase pathway. As they begin the transition to stationary phase, they instead reabsorb acetate, activate it to acetyl coenzyme A (acetyl-CoA) by means of the enzyme acetyl-CoA synthetase (Acs) and utilize it to generate energy and biosynthetic components via the tricarboxylic acid cycle and the glyoxylate shunt, respectively. The above bit of chemo-speak refutes Behe’s Krebs-cycle-is-irreducible argument by showing an alternate pathway toward phosphorylation and cellular energy production. From here To be able to show where Behe is wrong, you need a LOT of science. I agree, Behe’s concept is easy to state, but much harder to refute. I mean, do we spend a semester describing serial direct evolution, parallel direct evolution, elimination of functional redundancy, and adoption from a different function as the basis for evolution - all concepts that need to be understood if you're going to undertake to refute Behe? How much time do we need to spend going over the advanced concepts necessary to actually evaluate the claims? After Behe, do we look at spending time going over the concepts of geology and cosmology in detail in order to refute the YECs? How about a crash course in probability and information theory to refute Dembski? You get my point, I hope.
quote: At this point, since you’ve made the indoctrination assertion several times, I think I’m justified in asking that you provide evidence that this actually occurs — and that teaching evolutionary theory is the mechanism.
quote: I do get what you’re saying. I wouldn’t have a problem with laying out the basis for natural abiogenesis — and including the problems with each current theory. On the other hand, merely stating it’s unlikely therefore a supernatural entity/designer for which there is no positive evidence didit as the only alternative is utter bunk. As to that, IIRC we never even touched on abiogenesis (nor, come to that, evolution) when I went to high school. My high school biology class was primarily geared toward Linnean classifications, the basics of Mendelian genetics, brief coverage of ecosystems and biomes, photosynthesis and mitosis, etc. IOW, the real basics. I didn’t even hear the word evolution until I got into college. ‘Course, that was a looooong time ago, and I’m aware things have changed.
quote: And:
quote: Logical fallacy? LOL. Maybe, just maybe, it might be in response to statements like this, Cobra: The subject of origins is very sensitive and could even cause religous conversion. Given that your apparent entire concern in this whole evo-cre issue is religious, I think I’m justified in bringing it up. Feel free to prove me wrong. Try showing the nature of the designer in ID is not semantically and functionally equivalent to a deity.
quote: Okay, see quoted section above inre religious conversions caused by the teaching of evolution.
quote: Worse and worse. If Santorum is proposing legally mandated science education — the teaching of ID — with no background or understanding of science, that federal agencies will treat as law, then we have a major problem. In the first place, according to you — and I guess John West — the creationists have managed to circumvent the Constitution by forcing the teaching of a foundationless theory that is fundamentally religious (or if you prefer, supernatural) in nature. Secondly, Santorum has done this without being capable of understanding either the evidence for evolution nor the meaning of the lack of evidence for ID. Congrats, you’ve succeeded where every theist since 1783 has failed. Fortunately, I doubt the Santorum language will be considered by any federal agency to require or be capable of enforcement. [Edited to add overlooked attribution on the acetate kinase discussion.] [This message has been edited by Quetzal, 06-13-2002]
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Quetzal Member (Idle past 5903 days) Posts: 3228 Joined: |
quote: I probably didn’t explain it very well. The experiment relates to a subset of ID. The philosophical basis is that intelligence (undefined) is a real property (basically a vitalism approach) and pervades the universe — neatly sidestepping the nature of the designer question. I guess it’s pantheist, mostly. Anyway, the idea is that beneficial (adaptive) mutations can be internally generated by the organism itself — in contrast to the Darwinian random mutation — and that phenotypical changes can take place in the organism’s morphology and be passed on through inheritance BEFORE being encoded in the genome, based on either conscious or instinctive responses to changing environmental conditions. I’m not sure I understand the whole concept, but it would have serious implications for RM&NS if it could be shown that vitalism is a valid concept. It would go a far piece toward showing that design is a valid research path, IMO. Also, it wouldn't be that great a stretch to go from vitalism to a more "concrete" designer. In any case, it was just one idea. The IDists are going to have to come up with what would bolster and/or falsify their ideas — not me since I’m a dedicated evolutionist.
quote: I said it wasn’t a bad approach — reread that section of my post. I maintain, however, and for the reasons specified, that Behe’s irreductionism is a fallacy because it is based on false premises. All that is needed is to show that the particular IC structures he uses as examples are not IC. Even pointing out that variations on the theme exist shows that they aren’t IC — if they were, they’d be invariant, right? He’s free to come up with others, obviously — which will then have to be refuted in turn. He selected those examples he used based on a Paley’s watch type argument — which is at heart an argument from incredulity (we can’t imagine how a watch could be there without a watchmaker, therefore a watchmaker exists). If you prefer, you could justifiably characterize his argument as designer of the gaps rather than incredulity (we don’t understand how it formed, therefore it must have been designed.) Reread the quote from Behe’s own book in my post if you don’t believe me.
quote: Well, I’d say that if they could either make observations, inferences, or conduct experiments that could be replicated by any interested third party with the appropriate tools, then they can start claiming they have evidence. Think cold fusion.
quote: Since this section and the subsequent sections were primarily in response to your use of indoctrination, I’ll say we need to simply agree — to — disagree as both positions are based on opinion.
quote: Evidence — one way or the other — must be replicatable by other scientists — any scientist who takes a mind to do it. It isn't a question of fairness. ID needs to be subject to the same scrutiny to which any other scientific evidence is subjected. It must stand or fall on its own merits. Will the IDists have a tough row to hoe? Youdamnbetcha. Guess what? No sympathy here. If they hadn’t started with their political shenanigans before their science, we wouldn’t be having this discussion in the first place.
quote: Excellent response on the pseudogenes. I’m impressed. So how does ID explain them (you don’t have to answer if you don’t feel comfortable doing so — just be aware this is one of the bits of evidence for the ToE that will have to be addressed by ID, as well.)
quote: Without the science foundation, how can you provide the students with the reasons scientists think it’s wrong? All I’m asking is that if you are going to foist ID off on kids just learning the foundation of science — not the advanced concepts — then ID MUST have a strong empirical basis. It MUST have at least as much explanatory power and as much evidence as the ToE. Otherwise it’s no different than saying UFO’s are visiting the earth — although many scientists are trying to show they didn’t. At this point in time, equal time ideas are — to say the least — premature.
quote: On the one hand, I agree with you. Anyone that teaches that anything in science is true beyond doubt should have their credentials revoked. On the other, you’re begging the question I asked: please provide evidence that this occurs. I’m going to add to that (as a penalty) you need to convince me as well that the ToE is taught any differently than any other scientific concept in high school. Say, basic physics, chemistry, astronomy, etc.
quote: Why? Without evidence to support the alternative, why should it be taught — or even mentioned? Abiogenesis has at least some experimental underpinnings since at heart if flows from basic organic chemistry. Anyone who teaches that a particular abiogenesis hypothesis is right is jumping the gun, however. And certainly if it could ever be proven that chemical evolution CAN’T occur, then I totally agree it shouldn’t be taught. Except maybe as a curiosity of olden days science in the same context as Lamarckism or a geocentric solar system, etc.
quote: You’re presenting a false dichotomy here. Criticizing most of creationism (and a fair amount — although for the sake of discussion I’ll concede not all - of the ID brand as well) because it is at it’s philosophical foundation a religious, theistic worldview, is not criticizing its implications. It is criticizing its foundational principles. If, for example, ID were proven ultimately to be a valid scientific theory, and someone used that theory to push some sort of non-scientific social or political system, then it would be valid to criticize the social or political uses of the theory — just like it is valid to criticize the idiotic and misguided social Darwinism and eugenics ideas that people extrapolated from Darwinism to promote their particular agendas. However, it’s invalid to criticize either ID (in the hypothetical case) or Darwinism for that misuse. See the difference?
quote: I’m glad you’ve been through this argument before. That means you’ll be ready for the obvious follow-up question: If the LGM (little green men) created/seeded this planet with life, who/what created the LGM?
quote: No, it isn’t. The lack of positive evidence for ID is a fact based on the rather obvious lack of any published, replicated, verifiable experimental or observational evidence to date. Hey, I don’t mind waiting. It’s Santorum who’s jumping the gun.
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Quetzal Member (Idle past 5903 days) Posts: 3228 Joined: |
Cobra: I stumbled across an article written by a pro-IDist. Oddly enough, I find myself in near-complete agreement with Gordon's stance. I think you'll especially find his explanation of the "goal-directedness" part of ID (the bit I didn't get across very well when I was talking about possible research approaches) in the fourth paragraph interesting. Gordon very much echos my take on the current state of play of ID - even though we're coming at it from diametrically opposite standpoints. Intelligent Design Movement Struggles with Identity Crisis.
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Quetzal Member (Idle past 5903 days) Posts: 3228 Joined: |
blitz: I also have the same question John posed. I noted the "horizontal" adaptation/variation Morris mentioned, as compared to the "vertical" macroevolution. However, nowhere in that article did he mention either any way of identifying what constitutes an invariant type nor what prevents variation over time from becoming macroevolution. The only thing the article even mentions is a bald assertion that mendelian genetics "proves" that genetic diversity of organisms is limited: "As Gregor Mendel observed with his breeding studies on peas in the mid 1800's, there are natural limits to genetic change. A population of organisms can vary only so much." Needless to say, modern geneticists wouldn't agree. Morris also fails to identify those supposed "natural limits".
From the evolutionary side, if life evolves by selection of heritable variations, we should expect there to be such variation within modern species that it would be difficult to tell some species apart, and to tell species from subspecies, and subspecies from mere varieties. The longer these populations have been apart, the more they are divergeant. In addition, since similar environments exist in different parts of the world, if life evolves by descent with modification, making do with what exists in a particular place at the time, evolution predicts that equivalent niches will often be filled, not by the same organisms all over the world, but by different ones in each locality - in each place a different design answer to the same problems. This we regularly do find in nature, with similar niches filled with (often radically) different organisms. Finally, since lineages are constrained by their history (no saltation), there should be conserved genes that are "turned off" or no longer expressed. Experiments (surgical manipulation of a chicken's foetus that induce structures to grow that normally would not) have shown that chick embryonic jaw tissue can be persuaded to grow teeth in the right conditions, though no modern bird possesses teeth (but fossil ones do). The genetic instructions for their growth are present, even though they are not usually expressed. Furthermore, the growth of some structures induces the growth of others. The fibula in modern birds is normally just an (atrophied) splinter, and the tarsals are fused. Both reptiles and Archaeopteryx have full tibia and fibula and lots of separate tarsals. By simply inserting a piece of mica between the developing tibia and fibula of a chick embryo, Armand Hamp produced an Archaeopteryx-like leg , with not only a fibula fully to the ankle, but separate tarsals, as well as muscular adaptations required to make the limb fully functional. Here, better than any other, is a true "macroevolutionary change" - or as close to it as you're likely to see in under a few million years - produced in the lab, simply by manipulating existing genetic instructions. In short, Morris's article is highly uncompelling and vague. Perhaps you could link to a different article based on evidence that actually addresses the question concerning the putative barrier to macroevolution?
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Quetzal Member (Idle past 5903 days) Posts: 3228 Joined: |
[edited to remove weird double post]
[This message has been edited by Quetzal, 08-13-2002]
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Quetzal Member (Idle past 5903 days) Posts: 3228 Joined: |
Hey gene!
Yeah - the article I referenced did in fact produce genuine tooth buds.quote: (reference: Chen, Y-P. and nine others. 2000. Conservation of early odontogenic signaling pathways in Aves PNAS 97:10044-10049) is the one you were thinking of. AFAIK, Hampe's experiment produced a living chick (I don't know how long it lasted, however). Interestingly enough, subsequent tests of Hampe's experiment showed concurrent modification of muscles, etc, consistent with the growth of the bones, but showed that the physiological changes weren't an atavism! Anytime you changed the tibia/fibula ratio the rest of the body just followed along. IMO, this has significant implications for gross morphological change due to change in a single body ratio. So much for "it's still a chicken" since the morphological changes are consistent with the devo of reptiles... There are a lot of examples in nature - including humans born with fur, horses with three-toed feet, etc. This is one of the key reasons (of many) why I have such a problem with creationist arguments about some mythical barrier to kinds - evidently based on differential morphology or some kind of unidentified taxic discontinuity. There are simply too many examples where this "law" is violated.
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