Creationist response to cetacean femur, leg atavism, and limb bud.

Hi Aaron,Glad to see you back! I see you have been very busy. you've certainly provided me with plenty of homework. Since there's quite a bit of material here, I will tackle a bit at a time. I may expand this post later, or post again if I have more to say. I also showed you this image; It shows a Right Whale femur, very clearly leg-like and very clearly fused to the pelvis. It certainly looks fused to me. Where are you getting this idea about whale femurs never being fused?I also note that your previous claim seemed to be that the femur and pelvis were part of a single, non-fused bone. You seem to have moved away from that. In exactly the same place as one would expect to see a femur. Huh. There's a coincidence. In fact, lots of whales seem to display these "tumours", just in the right spot for a rudimentary femur. Mysterious ways indeed. I don't know about that. This Right Whale pelvis certainly looks like it has an acetabular notch; Further, here is a diagram from the Bergen Museum site, which clearly shows the acetabular notch; From here. They also have a shot of the other side of that very same Fin Wale pelvis that we were talking about, which is held at the museum! Small world. Anyway, they seem to recognise an acetabular notch in whales. Perhaps biologists have learned a thing or two since 1881.I have to wonder where you're getting your data. From an 1881 paper? Really? Except that Brazier is wrong. I mean, your own research turned up info on the ischiocavernous muscle, which you talk about in relation to the reproductive anatomy of Right Whales. Aaron, you have an ischiocavernous muscle! So do I! So does every human being and, I dare say all or most tetrapods.So yes, we can make homologies in the associated musculature around a whale's pelvis. I concede that you have done a great job on the reproductive function of the pelvis. However, I still think that what I wrote is true. The high individual variation must still drown out the importance of the sexual variation to at least some extent. However, this in no way argues against an evolutionary origin for whales or in favour creationism. It is no coincidence. All but the Sperm Whale are members of the same family, Balaenidae. Of those all the Right Whales are of the same genus. It is only to be expected that they would share homologies. This is clear evidence of their evolutionary relatedness. You are drawing cladograms. Again, these are all closely related. All are of the same family, only the Humpback is outside of the Balaenoptera genus. You are only highlighting their relatedness. Sir Bowhead Whale, we salute you! As I have said, all this stuff about reproductive anatomy and a function ofr the whale's pelvis is good work. i agree that the pelvis of the Bowhead plays a role in its reproductive success.I am less clear what function the femur or tibia might play. Or why this role must necessarily involve a bone that strongly resembles a pelvis. If the bone is novel and not related to a pelvis, why is it so similar? Once again, i can only conclude that God really wants us to believe in evolution. I couldn't find that paper. Could you provide a link?I did find this, by the same author;

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Comparative anatomical study on the structure around the pelvis in the finless porpoises (Neophocaena phocaenoides)

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Abstract;The morphology of modern cetaceans results from adaptation of ancestral terrestrial mammals to aquatic life through evolutionary processes. Consideration of the causes and processes of the loss of hind limbs and the reduction of the pelvis are interesting and important. Some primitive fossil cetaceans are known to have both fore- and hind- limbs. In modern cetaceans vestigial pelvic bones are, in general, a pair of slender rod-like structures within the abdominal wall muscles just anterior to the anus. The pelvic bones do not have bony articulations with the axial vertebrae and have no appendicular skeleton, except in some great whales, which occasionally have rudimentary femora (Burne, 1952; Nemoto, 1963; Ogawa and Kamiya, 1957; Slijper, 1958). In the present study, the pelvic bones of the finless porpoise were confirmed to follow the basic form and configuration of cetaceans. Muscles such as M ishciocaudalis, M ischiocavernosus and M bulbospongiosus have attachments on the pelvic bones in both sexes. Moreover, we confirmed that the caudal end of M. rectus abdominis (RA) constitutes a strong dorso-caudad aponeurosis (Fig.1, B), after sending a small muscular slip to the pelvis (Fig.1, A) and inserting at the superficial fascia of M. ischiocaudalis (Fig.1, C). In the most caudal portion of M. transversus abdominis (TA), the strong inner fascia of TA originated at the Proc. transverses and suspended the pelvis as part of the abdominal wall (Fig.2). It should be emphasized that insertion B is much the same as that of the terrestrial mammals. As mentioned above, some soft tissues around the pelvis are transformed following the drastic transformation of the pelvis. This transformation tells us that cetaceans adapted to aquatic life during evolutionary processes, choosing the tail flukes operated by the powerful trunk muscles for locomotion instead of modifying the hind limbs into hind flippers as seen in pinnipeds....

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SourceOnce again, the evidence for creation/against evolution that you cite seems to have slipped by its authors without their ever noticing it.Overall though, I don't see how a function for the pelvis argues against its vestigiality. Vestigiality does not preclude function. I have made that clear several times. You say; but that is merely a gripe about the term "vestigial", not an argument against an evolutionary origin for the whale.Okay, I'm going to take a break for now, but I do have more to say. I will post again later.Mutate and Survive

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On two occasions I have been asked, — "Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?" ... I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question. - Charles Babbage

Hi Dr A, Await away, but don't expect anything before tomorrow evening. I was planning to comment on Aaron's claims about limb development and about his ideas about supernumerary limbs.Now though, I'm off to bed, I've work in the morning. Those cats won't shave themselves.Mutate and Survive

Okay, let's take a look at the developmental side of things. For the record, I pointed out that mice lacking SHh formed vestigial limbs, comparable to those of cetaceans. Aaron responds; I agree that the clue is in the title. "Mice lacking SHh". These mice lack all SHh expression. This is patently not the case in whales. If it were, they would not be able to form their front limbs. Indeed, they would not be able to develop at all and would die.Instead, we can see that SHh is active in whales, but inactive in their hind limbs. But this is not all. Take a look at this summary of an interesting paper on whale embryology;

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Analysis of the development of limbs in a small number (fourdolphin embryos are not easy to come by, or casually used) of river dolphin (Stenella attenuata) embryos was sufficient to come up with a straightforward picture of the differences in molecular development.

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Cetaceans form the AER for both the fore- and hind-limb. They express Fgf8. This is the normal tetrapod pattern.

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Cetaceans form a ZPA for the forelimb. Hand2 is expressed broadly at first, and then is restricted to just the posterior part of the fore-limb; Shh is expressed in a perfectly ordinary fore-limb ZPA.

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Hand2 is not expressed in the hind limb region. Shh is never activated. No ZPA forms for the hind limb, and the structure arrests and ultimately regresses.

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Source. The paper this is taken from is here.What this is telling us is that SHh regulation is indeed a culprit in producing the vestigial cetacean hind limb, but it's not the only factor. The whales don't suffer any ill effects from lack of SHh because they don't lack SHh. Their SHh production is completely normal, except in their hind limbs.It also shows us that it only took relatively minor changes in signalling protein regulation (during development) to create the modern form off the cetacean hind limb. As I mention above, this is not even a consideration. Whales possess functioning copies of all of these molecules. They simply have mutations that affect the expression of these molecules in their hind limbs. The genes for these essential signalling molecules are still there, they're just selectively expressed. As we have seen though, other factors are at work, such as Hand2. That researchers are yet to find out how to exactly recreate the kind of structures that we're talking about only means that they haven't sussed it out yet. It does not argue against SHh, Hand2, Fgf and other factors creating the cetacean hind limb. Yes, and we can see from Thewisson's paper that this is exactly what happens.

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We found that embryos of the pantropical spotted dolphin (S. attenuata) display a hind-limb bud with a morphologically distinct AER at their tip around embryonic stage Carnegie 13 (7). The AER persists and hind-limb bud outgrowth is sustained through Carnegie 15 (Fig. 1 A and B). Shortly thereafter, distal ectodermal cells lose their columnar shape, and the AER is lost (Fig. 1 C and D). After this degeneration, the hind-limb bud diminishes in size.

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To determine whether the AER of the dolphin hind limb is functional at a molecular level, we next investigated whether it expresses Fgf8. Fgf8 protein localizes to the AER in both fore- and hind-limb buds of Stenella at Carnegie 14 (Fig. 2 C—F), consistent with the expression pattern in chick and mouse embryos (14, 15). By Carnegie 16, however, Fgf8 is undetectable in the hind-limb bud ectoderm. These results suggests that the dolphin hind-limb bud initially has a functional, albeit transient, AER.

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So yes, the limb buds are indeed limb buds and they do display an AER. It just gets disabled (at about Carnegie stage 16, just as Aaron mentioned). Except that surgically removing the AER would not create a situation which could be fairly compared to that observed in dolphin embryos. It would not have the same effects upon Hand2, FGf8 or SHh expression that were observed by Thewisson et al.This is not a fair comparison. All arguments based upon this comparison are invalid. they seem to be similar enough to fool a team of anatomists and zoologists into thinking they were limb buds, even when they examined them in the tiniest detail.They look like limb buds. They behave like limb buds. They have the same chemistry as limb buds and, if they are allowed to grow, they form bones that are homologous to limbs.This is a remarkable co-incidence. Well, either that, or they really are limb buds.Incidentally, all this business about inactive signalling molecules may explain the appearance of femurs in Sperm Whales, even though they are toothed whales. The Sperm Whales would still carry all the genes needed to make a femur. It would just be disabled at the development stage. It would only take a few small mutations in the regulation genes and the femur and tibia would simply reappear, much like the way that modern chickens can be induced to grow actual teeth, with the application of the right signalling factor. the genes are still there. it's just the expression of those genes that has changed. As such, the appearance of femurs in an toothed whale doesn't sound quite so anomalous. With all due respect Aaron, I couldn't give a pair of foetid dingo's kidneys what they thought in the 1880s. They had an incredibly poor understanding of embryological development back then. You shouldn't be relying on such grotesquely old papers.One last thing before I wrap this up. The Thewisson paper doesn't restrict itself to looking at modern whales. it also posits some theories about whale evolution, based on their findings about how whale hind limbs develop.

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Interpreting our results in the context of both the cetacean fossil record and the known functions of Shh suggests that reduction of Shh expression may have occurred ≈41 million years ago and led to the loss of distal limb elements. The total loss of Shh expression may account for the further loss of hind-limb elements that occurred near the origin of the modern suborders of cetaceans ≈34 million years ago. Integration of paleontological and developmental data suggests that hind-limb size was reduced by gradually operating microevolutionary changes. Long after locomotor function was totally lost, modulation of developmental control genes eliminated most of the hind-limb skeleton. Hence, macroevolutionary changes in gene expression did not drive the initial reduction in hind-limb size.

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Here is a nice diagram showing when they think these changes may have taken place. So in stark contrast to any claim that examination of cetacean limb buds proves that they are non-limb related structures, in fact, such research shows strong evidence that the buds are indeed limb buds. Further, it sheds light upon the evolution of whales from their longer-limbed ancestors, such as Basilosaurus.Mutate and SurviveEdited by Granny Magda, : No reason given.

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On two occasions I have been asked, — "Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?" ... I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question. - Charles Babbage

Continuing... Agreed. You haven't provided any evidence that any whale "femur" is actually a bone tumour. Indeed, it does not resemble a tumour. It resembles a femur. plus, as Dr A has pointed out, it seems instructive that these alleged "tumours" always appear where the femur should go.I know exactly why the femur always appears where it does.Can you suggest why a bone tumour should overwhelmingly favour that site? Further, since you are explicit about your belief that God created the whale, why would he create them so as to display bone tumours that so closely resemble femurs that even the world's top zoologists can be fooled? Why is he so keen to make these animals look evolved? Just like the cartilage that we have on our acetabular cavities. Another homology. It absolutely is a debatable point. The picture I presented showed a very clear notch, right where the acetabular notch should go. Right where the femur does go. What else could it be?Certainly, it is far less pronounced than a terrestrial animals acetabular notch, but that is not surprising. This is part of a pelvis that is attached the wrong way round! It is a highly derived, very unusual pelvis. We should not expect it to be a perfect match for terrestrial animal pelves. Rather, we should expect that it would look very different, with some features missing and some grossly warped. This , in fact, what we see.I also think that the reason behind the drastic reduction of the acetabular cavity is pretty obvious. It no longer articulates a mobile, weight-bearing femur. It is no longer part of a skeletal system that is used for quadrupedal locomotion. Without this function, it seems almost inevitable that natural selection would not be able to shield this near functionless appendage from the effects of mutations. The feature would diminish, just as we see today. From looking at the available literature, I agree that the modern whale pelvis is considered to be homologous to the ischium. You're right about that. However, homologies still exist. Much as you might try to deny them, the homologies around the ischium - the acetabular cavity, the femur, the musculature (more on that in a moment) - the comparisons are obvious. The pubis and ilium might be impossible to detect, but there is plenty more to go on. Just because two mammals have a muscle, that extends from the pelvis to the base of the penis/clitoris, doesn't mean that there is any connection between those muscles. Uh-huh.It is described as a homologous ischiocavernosus muscle in the scientific literature, such as in Notes on the Anatomy, Postioning and Homology of the Pelvic Bones in Small Cetaceans, where the ischiiocavernosus and the levator ani are explicitely described as homologous.

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In this study, the attachment of two muscles to the pelvic vestiges — levator ani and ischiumcavernosus is confirmed. The levator ani is attached to the haemal arches and to the ischium of many mammals, including the artiodactyls (Habel, 1975). There is currently a broad consensus that, among the extant groups, artiodactyls are the most commonly cited as the sister group of the Cetacea, and that perhaps they even form a clade (Gingerich et al. 1983; Thewissen et al., 1994; Gatesy, 1997, 1999; O’Leary and Geisler, 1999; Gingerich, 2001, Gatesy and O’Leary, 2001; Thewissen et al. 2001). In cetaceans, this muscle arises in the haemal arches and is inserted to the dorsal margin of the pelvic bone (Lessetisseur, 1968: 692-693), more specifically at the dorsolateral crest and ventromedial protuberance of the cranial process, a name suggested by Duvernoy (after Arvy, 1979).

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The ischium-cavernosus muscle arises in the ventrocaudal portion of the pelvic bone, which is usually called ischial tuberosity, both in cetaceans and in all other mammals

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But the paper I just cited disagrees with Brazier. Clearly it is more debatable than you think. It's odd how you simultaneously cite Tajima and yet don't believe a word he says. When he says that whales may use their pelves in locomotion, you jump on it. When however, he says;

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Muscles such as M ishciocaudalis, M ischiocavernosus and M bulbospongiosus have attachments on the pelvic bones in both sexes. Moreover, we confirmed that the caudal end of M. rectus abdominis (RA) constitutes a strong dorso-caudad aponeurosis (Fig.1, B), after sending a small muscular slip to the pelvis (Fig.1, A) and inserting at the superficial fascia of M. ischiocaudalis (Fig.1, C). In the most caudal portion of M. transversus abdominis (TA), the strong inner fascia of TA originated at the Proc. transverses and suspended the pelvis as part of the abdominal wall (Fig.2). It should be emphasized that insertion B is much the same as that of the terrestrial mammals.

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you dismiss him out of hand. You are cherry-picking. If you think that Tajima possesses sufficient expertise to correctly diagnose an active role in locomotion of the cetacean pelvis, then you really ought to credit him with enough expertise to tell which muscle is which.The fact remains that the source you cited regards the ischiocavernosus muscle as being homologous with that of terrestrial mammals. Yes, I think it's fair to say that laymen such as myself make mistakes on this. The pubis and ilium being a good example. I will admit to being wrong on that myself. However, the mistakes made by layman enthusiasts such as myself do not count as serious flaws in evolutionary thinking. You cited the technical literature. That work, has built a scientific consensus that goes against many of your claims. The experts in the field regard these bones and muscles as being homologous with those of terrestrial quadrupeds. You can't get away from that. Except that you cannot provide us with an explanation for why these bones so resemble legs. I can. Vestigial is that reason. Meanwhile you are forced to grope around for a pot-pourri of diverse rationalisations, from bone tumours to muscle anchors that must, for unspecified reasons, resemble legs.I think that far from being propaganda, vestigiality is by far the most parsimonious explanation for these features.Mutate and Survive

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On two occasions I have been asked, — "Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?" ... I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question. - Charles Babbage

Yes, I know. We are agreed on what happens in this case. Just because it cannot be recreated does not mean it never happened. This only argues for the imperfection of scientific expertise in an area with little opportunity for study. Or do you think that scientists are gods, able to recreate anything that nature can do? One minute you act like the scientists should be able to achieve anything they might want, the next, you are dismissive of their findings. This is a strange attitude. Do you have any evidence for that? Please cite it if you do.Still, I don't see why you expect cetacean limbs to behave exactly as those of terrestrial mammals, when, as you yourself have gone to great pains to point out, they have undergone a lot of adaptation in specialising for new roles.Embryological development is incredibly and to expect that human scientists should be able to reproduce any given condition in the lab is naive. And what happens when the proteins are down-regulated but the AER is not removed? Can you tell me that? Because that's what is happening in whales. That is what happened in Thewisson's dolphins.If you can show me an experiment where that happens, then great, but until then, the mouse experiment is not one that I consider a perfect match. It is instructive yes, and indeed it shows that SHh down-regulation results in reduced limbs, but it is not reproducing the exact situation that we know occurs in whales. What is your evidence for that? Yes! Also because of all the other similarities I have outlined - anatomy, morphology, chemistry. Indeed, the only areas in which is does not resemble a limb bud are those factors that would have to be different for the limb to have evolved the way it did.Yes! They have to be! If they were not, a full hjind limb would grow there!In fact, this would suggest a fantastic creationist experiment. Take one dolphin embryo. Open up the flank and expose the limb bud at around Carnegie stage 15/16. Introduce SHh and Hand2. If it grows into a great big whale boob, then you have falsified the hind limb hypothesis. But sadly, creationists organisations don't show much enthusiasm for actually doing science. Aaron, you have to get out of this bad habit of citing studies without actually citing them. Which studies? Please name them and, if possible, provide a link. It is not fair to ask me to do your homework for you. No, you misunderstood what I was saying. I was talking form an evolutionary, natural history point of view. I was talking about the whole species, not individual Sperm Whales. The point remains that no genes were lost during the process. They were simply down-regulated in a single area. That, in one species, that down-regulation should be weakened is not all that astonishing. It is surprising - don't think that I didn't notice the presence of a toothed whale amongst your list of mysticetes - but when we see how small a genetic change is required for the femurs to reappear, it seems like small beer. Please. They knew about anatomy. Anatomy is not embryology. This kind of highly detailed embryology is new. They did not know about the chemicals and processes we're discussing in the Nineteenth Century. They had no way to examine the chemical side of embryological development. SHh was not discovered until 1978 and it was not understood until 1995. These things are still being discovered now and we still do not have an especially full understanding of their function. To suggest that a Nineteenth Century understanding of embryos is comparable to our modern one is just silly.Mutate and SurviveEdited by Granny Magda, : No reason given.

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On two occasions I have been asked, — "Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?" ... I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question. - Charles Babbage

HI Robert,Oh dear. You have decided to clutter up Aaron's nice thread.Suffice to say that, where Aaron brings evidence, you bring nothing. You say "This YEC creationist insists", as though your insistence alone could make your fantasies true. It's pathetic.Even worse, where you do make specific claims, you are painfully wrong. That is wrong. Not just a little bit wrong, but staggeringly, woefully, embarrassingly wrong. Just google Sirenians to see how wrong you are. They display very similar hind-limb structures to those of whales. Further, there are vestiges and homologies throughout the animal kingdom.That is evolution you strange man.Look, you're not achieving anything here beyond letting your amazing ignorance hang out for all to see, so might I ask that you don't mess up this nice thread with your vague and semi-literate ramblings? Please? Thank You.Mutate and Survive

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On two occasions I have been asked, — "Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?" ... I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question. - Charles Babbage

Hi Aaron, I understand that. You still have no evidence that this is a tumour though. I agree that it is an abnormal case. Nonetheless, that paper does identify homologies, so it can't be that much of a problem. Your only answer to this is that they are engaged in wishful thinking, which I find rather dismissive. I think that is too tenuous to be regarded as direct support for Brazier's statement. The fact remains that work is being done to identify homologies in the muscles around the whale's hind limb. The work is being done and, difficult though it may be, those homologies are being found. Clearly Brazier was over-egging it a little when he said it was "utterly impossible". So you do disagree with Tajima. You selectively disagree with him, based not upon his paper or its contents, but upon your preconceived bias against evolutionary explanations.The fact remains that the paper you cited explicitly describes the ischiocavernosus as being homologous with that of terrestrial mammals. Is there a major building block of your argument that you feel I have not addressed?Oh, by the way, you may have noticed that I mentioned sirenians up thread. Sirenians are the group that includes manatees and dugong. They are aquatic mammals too. Guess what they have... Given that your explanations for the cetacean pelvis have so far been somewhat piecemeal, I can't help but wonder how you explain the presence of hind-limb remnants in yet another aquatic mammal.Mutate and Survive

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On two occasions I have been asked, — "Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?" ... I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question. - Charles Babbage

Your main points are;
a) Evolution is false;
b) Living things were created by God and;
c) Whales did not evolve from terrestrial vertebrates.Did you run any of that past those biologists?Mutate and Survive

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On two occasions I have been asked, — "Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?" ... I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question. - Charles Babbage

Hey Byers, That you did. Fair enough.So you acknowledge that marine mammals evolved. That means that you have nothing further to add to this thread. This thread is for those who wish to argue that whales did not evolve from land animals. If you think that they did, you have no role to play here. Please stop posting here. No-one could care less about your guesses, especially in a thread where a creationist member has gone to such efforts to provide evidence for his position. Since you provide none, you have no business posting here. Please stop. You are ruining Aaron's nice thread. If you want to argue that evidence for evolution is evidence against evolution, do it somewhere else.Mutate and Survive

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On two occasions I have been asked, — "Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?" ... I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question. - Charles Babbage

Hi Aaron, Well good. That means that your comment; seems to be irrelevant. It's not. The changes needed to suppress the limb are far less profound than those needed to create it in the first place. The whales still have all those ancestral genes that allow them to make hind legs. We can see this from the atavisms. All that has happened is that the expression of those genes has changed. This is a comparatively minor change. Obviously all biology is complex, but this is not as big a change as you seem to want it to be. Well you can't expect me to comment on a paper that I can't read. I do notice though that the authors still refer to the hind limb buds as hind limb buds in their abstract. They do not seem to see the problem you see. I also probably lack the knowledge of embryology to fully answer this one to be honest.I'd still like to take a look though. Is your copy of this paper a digital one? If so, I would be grateful if you were to email me a copy. My email address is at the bottom of this post. Well since chemicals are physical, I suppose that one answer is yes. The general point I am trying to make here is that it seems perverse to rely on century old research when more recent research is available, with new methodologies and new data. New research supersedes old research, usually. That is a view that I do not think you have fully supported. I am interested in your thoughts about them because you seem to doubt that the hind limbs of whales are hind limbs. You seem to think that they are supernumerary front limbs (although how you square that with your observation that the pelvis is recognised as an ischium, I don't know, since the two views are quite incompatible). So do Sirenians have supernumerary front limbs too? Exactly where their hind limbs should go? Isn't that a bit of a stretch that the same deformities should occur in two unrelated species? Can your ideas explain Sirenian morphology, or must that be answered separately? What about Pinnipeds? Their hind limbs form a tail. Can your ideas answer that? And then there's the extinct marine reptiles, like plesiosaurs...Is there a general principle at work here? Because I can point to a general principle; they are all examples of tetrapods evolving into an aquatic lifestyle, with their limbs being adapting to match.If you have no general principle you are left with a series of mismatched, piecemeal explanations and that has to look a lot like a set of post hoc rationalisations.Mutate and SurviveEdited by Granny Magda, : No reason given.