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

I'd like to join GM in welcoming you back, it's a pleasure to have a creationist with such a high standard of debate. (We're still going to metagrobolize you, but that's the price you pay for being a creationist.)I shall wait for GM's promised second post before I see if I have anything to add, because otherwise we are likely to waste time covering the same ground.P.S: Thanks for the hot whale porn.

But since the production of any part has a biological cost, we should expect parts without any function to be eliminated by natural selection by and by. Which suggests that they should be a minority.

But the specificity is not seen nearly so clearly as the homology. One does not look at GM's pictures of whale pelvises and think: "By golly, that looks like exactly what an all-wise God would have thought of to attach a right whale's penis to!"Or consider the wing of an ostrich, where the homology is even clearer. Ostriches, you will perhaps say, use their wings for running. But it is hard to see that the form of the wings, so closely resembling that of flying birds, was specifically designed for this task. Meanwhile God bestowed ordinary arms on other flightless bipeds such as hadrosaurs, because that was best for them ...Eyeless crabs use their eyestalks for ... actually, I don't know what, except that if you just removed them the crabs would have holes in their heads which might provide ingress to disease and parasites. But whatever they use them for (if anything) it is easier to see that they are homologous to eyestalks than it is to see that they are the ideal design to do something else completely and just by chance this function is best served by things which look just like eyestalks.What we see again and again is that a supposedly omniscient God designed some organism and it just so happened that every single time the best solution he could think of was one completely in line with evolutionary biology. Now the optimality of these solutions is not seen so much as hoped for; and the magnitude of the coincidence goes entirely unexplained.

While we wait for GM, a few words about atavism. I should like to see more detail and quotations on this. In the meantime, a couple of thoughts:1.) If femurs reverted to an ancestral growing pattern, they would in fact grow outward not inward.2.) Growth is a self-coordinating process. Your freaky animals, for example, did not just produce extra bones. They got the muscles and tendons and nerves to match. It did not require a suite of mutations. How much easier would it be for tendon attachments not to develop during abnormal development?But I should really like to know more about this, and preferably from the horse's mouth rather than yours. What I've been able to find myself with an admittedly cursory look round doesn't seem to bear you out. E.g: The resemblances between your front and back flipper are the usual resemblances we find between forelimbs and hind limbs; the femur resembles the humerus; the fibula and tibia resemble the radius and ulna; and both have phalanges distally.But the differences are much more striking. My hindlimbs resemble my forelimbs much more closely than these flippers resemble each other. My hands and feet have the same number of digits, for one thing, and the same number of phalanges on the digits; and my feet have tarsals corresponding to the carpals in my hands, unlike this particular whale. But no-one would claim that I have hands on the ends of my legs despite this greater degree of similarity.Your hind and front flipper have less similarity than is usual in mammals, and you would have done well to keep quiet about it.We may also note that the digits in particular resemble the hind limbs of our old friend Dorudon. (Photograph here.)Your claim that they are actually forelimbs that have got into the wrong place is therefore unsubstantiated anatomically.Now let's consider their position. As your photographic freakshow demonstrates, the sort of anatomical abnormality you postulate can crop up anywhere on the body. Yet in cetaceans, time after time, these disputed atavistic hind limbs crop up exactly where hind limbs belong. Again and again, we see what look like the feet of primitive whales (which you claim are an extra pair of hands) attached to what look like a fibula and tibia (which you claim are a radius and ulna) attached to what looks like a femur (which you claim is an epipubic bone) which sprout at the same position at which whale embryos develop what look exactly like limb buds (which you claim are incipient mammary glands) and at the same position at which Dorudon had hind legs (which you claim are sexual claspers specially designed by God for that purpose). We do not equally commonly see these structures sprouting from elsewhere on whales, nor indeed do we equally commonly see hands sprouting out of the epipubic bones of kangaroos.Would not this observed regularity (if not explained in an evolutionary way) require either a massive series of coincidences, or for God to have weighted the dice in such a way as to delight evolutionists?And does not your explanation for all this seem somewhat strained compared to the straightforward evolutionary explanation? Everything has to conspire separately and in a piecemeal fashion to make it look like evolutionists are right. The whale, alone of all creatures, has to develop what look like limb buds but are in fact incipient mammary glands. The whale has epipubic bones, which most mammals get along without, and just happens to be prone to developing freak forelimbs attached to them which don't look like the forelimbs of whales. The best design for Dorudon's "sexual claspers" happen to look like limbs and be sited where hindlimbs are sited in basal mammals, and when whales develop freak extra forelimbs they just happen to always develop them in the same place ... and all this has to be arranged by a God whose intention is not to make evolutionists happy, but who made all these separate choices for perfectly good reasons whereof we know not ...... and on top of all that, it's not like this kind of thing is confined to whales.Edited by Dr Adequate, : No reason given.Edited by Dr Adequate, : No reason given.

It is, of course, a logical inference, not a convenient excuse. This is why you are reduced to making dumb assertions rather than finding an actual flaw in my logic. We can. We can even see completely useless vestigial features before natural selection has weeded them out, which is what I presume you were trying to say, if they are (a) sufficiently recent (as in animals recently adapted to cave-dwelling, for example) (b) subject to only small selective pressures (as in the case of pseudogenes) (c) preserved in intermediate forms in the fossil record (as in the vestigial legs of primitive whales). Ah, that good old standby of creationism, the non-quantitative quantitative argument.While you're (a) doing some actual math (b) counting all the vestigial features in the world, the rest of us will continue the discussion. Come back when you've finished and tell us how you got on. It would be pointless for me to speculate on whether ignorance or dishonesty impels you to come out with nonsense like this; but I would point out that both conditions are in principle curable.Edited by Dr Adequate, : No reason given.

Hold on. Surely those photographs are taken from the inside looking out; that is, with the medial side facing us. This is why the attachments of the corpus cavernosum are on the side facing us. And why the femur is on the side facing away from us. Granted, but you can't claim that the similarities are so great as to particularly suggest that the hind flipper is a Hox-mutation induced duplicate of the front flipper. If you now wish merely to claim that the differences aren't so great as to prove that it definitely isn't, then that is a much weaker claim. I could only see two on the photograph; do you have a reference? Thanks. Well according to this, that isn't a "rounded carpal bone", or even a rounded tarsal bone. That's the femur (or, according to your "front limb" hypothesis, the humerus). The next two bones are the tibia and fibula (or, according to your "front limb" hypothesis, the radius and ulna); there are no tarsals (or carpals); and then after that we get into phalanges.The passage quoted in the link doesn't say how they reached this identification of the bones, but they did look at the whale and we didn't. It's like Pakicetus. Seriously, again I'd like a look at your source material before coming to a conclusion. I did not intend to misrepresent you. We discussed these "claspers" at length and you never so much as hinted that you didn't think that that was their function.Indeed, what you wrote about Dorudon was as follows: Now, you did not mean that you had probably read reports saying this about Dorudon, did you? You meant that this was probably true of Dorudon, did you not?So how did I misrepresent you? Given that limb formation involves the production of bones, muscle, nerves, blood vessels, etc, so must the formation of pretty much everything else.Also, we do not actually see these supposed extra forelimbs growing out of the genitals or the mammary glands, do we? We see them growing where the hindlimbs would grow.Do we, in other mammals, see a consistent pattern of extra hands growing out of or near the breasts and genitals? Or does this by a freakish coincidence only happen in whales? I should think that that would vary from case to case. It must be difficult to catch happening, especially in whales, so I doubt that there is hard evidence in this case. The facts are interesting; his gloss on them I found rather silly, for reasons which would be outside the scope of this thread.Edited by Dr Adequate, : No reason given.

I'll leave the genetics to GM, who has a head start on me. A few words about embryology, though. Very familiar. This paper, for example, on the humpbacked whale, describes an embryonic stage at which the "peg-like hind limb buds" are visible and "a bilateral thickening, the milk line, extends between the limbs". The ridge and the hind limb buds are two different things. Like in all the other mammals.(Incidentally, while looking this up I noticed that a human embryo develops and then loses supernumary nipples along the milk line, but that would be a subject for your other thread.) Also, they don't turn into limbs. That's another difference. I wonder if there could be some connection between these facts.

"Very" similar? I would dispute this. Do you have a primary source for this, please? Only it seems incredible to me that any anatomist could look at the caudal vertebrae of a whale and not identify them as caudal vertebrae.Edited by Dr Adequate, : No reason given.

Cool, can we see?Does the hind limb of Dorudon have three digits? Only as I say I can only see two on the photograph I linked to. I'd have guessed the same, but I am supposing that the people who actually looked at the whale must have had some reason for dismissing the intepretation that seemed obvious to us. People like things that seem obvious. ... or in the hind limbs of other mammals.Also I would point out that we don't really know its shape, we know its silhouette as x-rayed from one angle. My femur would look that shape if you x-rayed it end on ... Thanks. I wasn't.What is troublesome about your agreement that they are sexual claspers is that you also seem to believe that they were specially designed by God for that purpose ... in which case it is odd how strikingly they resemble legs specially designed for walking with. And yet there do seem to be one or two howlers in there ... Lets be clear about this. Does anyone affirm that the hind limb buds are incipient mammary glands?

Yes, he thought that the flukes were the feet, but not that the tail was the legs.As to your original assertion: ... Ryder himself didn't believe this, and he makes it clear that even his views on flukes were heterodox in his day:

Wouldn't it be better if it was checked before publication?You've made some pretty bad blunders so far, and it would take a lot of luck for the stuff you haven't had scrutinized to be completely accurate.Edited by Dr Adequate, : No reason given.

Thanks It does have a third digit.It is still more like the atavistic hindlimb than is the forelimb of a modern whale. Who is he, and more importantly what exactly did he say? Your interpretations of the writings of scientists are somewhat ... haphazard, shall we say?

Well if you want to be wrong about everything except marine mammals, this would be exactly the wrong thread to do it on.

Did I tread on your toes?It is simply a fact that you have misinterpreted some of the things you've read. Probity on your part and skepticism on mine would therefore dictate an attitude of caution towards your opinions on what scientists mean when they say things. What if you're not correct? So far it seems more likely. It lacks context. Again, context is lacking. They may very well be Hox mutations. The question then would be whether they produce an atavistic hind flipper or a duplicate front flipper.

Curious. Had it been me I should have pointed out that the hind flippers are anatomically clearly not "multiplying existing" front flippers; that their locations, so far from being "unique", are singularly repetitious; and that it is by no means "parsimonious" to explain piecemeal the several and separate features that evolutionary biology explains at a single stroke. Indeed, I have already pointed this out. These observations seem to me superior to an appeal to anonymous authority.Edited by Dr Adequate, : No reason given.