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Author | Topic: Why are Haeckel's drawings being taught in school? | |||||||||||||||||||
randman  Suspended Member (Idle past 5151 days) Posts: 6367 Joined: |
WK, I am just stating that to argue they are homologous, you still need to argue within a boundary of language that reflects a basic honesty in approach. They are not gill pouches because they don't ever become gills, are not gills, and are not the same structures as fish gill pouches.
Now, if you want to argue these folds and fish gill pouches are similar structures that show common descent, that's fine. State you consider them homologous and present the data, but don't start off with a false claim they are the same structure and gill pouches. That's the same old thing Haeckel did in claiming they are recapitulating an earlier form. They are not recapitulating at all. They are in process to fully and only human forms, and moreover they are not identical. They cannot be the SAME, by definition, unless identical. You want me to argue whether or not they are homologous, but this thread and forum is about education, and as such, regardless of whether they are homologous or not, my points stand, which are that the way this is presented is false. In fact, arguing 2 different structures are homologous, and then arguing they are the same structure and even calling them by the same name!!!! is totally false. I don't care how you slice it. That dog don't hunt. Either they are identical structures, and thus we are not comparing 2 different structures, or they are 2 different structures that are similar (or not). Which is it? The way this is presented needs to be changed. Human embryonic neck region folds are not gills, neither gill pouches, etc,... If you want to say the structures are so similar they are likely homologous, fine, but that's a secondary point. This message has been edited by randman, 07-08-2005 03:15 AM
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randman  Suspended Member (Idle past 5151 days) Posts: 6367 Joined: |
These ridges do develop into those structures, and they develop into the craniofacial structures, elements of the endocrine system and jaw bones in fish as well, what do you know, another similarity. So really they are not even gill pouches or gill slits in fish!!??? Gimme a break. You guys need to do some major overhauling in the way you present this stuff to the public. I mean not only are they are not gill pouches in humans at all, but not gill pouches in fish either!
Do you just want us to change the name? Oh wait, biologists already mostly use branchial and pharyngeal so I guess we already did. Earlier I slammed the use of pharyngeal, but made a mistake there. I think the use of "branchial" is highly misleading since they are not branchia.
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Wounded King Member (Idle past 284 days) Posts: 4149 From: Cincinnati, Ohio, USA Joined: |
So really they are not even gill pouches or gill slits in fish!!??? Gimme a break. You guys need to do some major overhauling in the way you present this stuff to the public. So you want us to call them craniofacial-endocrineal-branchial arches instead in fish? Catchy name.
I think the use of "branchial" is highly misleading since they are not branchia. Do you have any idea what you are talking about, because you don't seem to. And even when we tell you where you are mistaken you keep making the same mistakes. I already pointed out previously that they are correctly called pharyngeal throughout the vertebrates, at least for any organism with a pharynx, and branchial in organisms, such as fish and amphibia, in which there are gills either transiently or permanently. TTFN, WK
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Wounded King Member (Idle past 284 days) Posts: 4149 From: Cincinnati, Ohio, USA Joined: |
You want me to argue whether or not they are homologous, but this thread and forum is about education, and as such, regardless of whether they are homologous or not, my points stand, which are that the way this is presented is false This just seems to be degenerating into an argument from semantic pedantry. If what you want is to expunge all historical terminology, over generalisations and simplifications from education then you have quite a task ahead. Are you going to get around to tackling Bohr's atom at all? In fact surely the very word atom should be removed since what we call 'atoms' can be divided and the word atom is rooted in the concept of indivisibility. Oh dear, the way the whole of nuclear physics is taught is false. TTFN, WK
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hitchy Member (Idle past 5370 days) Posts: 215 From: Southern Maryland via Pittsburgh Joined: |
Interesting how even Wells uses the terminology--
Only after gastrulation do the embryos of mammals, birds, fishes, and reptiles begin to resemble each other. In the pharyngula stage, every vertebrate embryo looks vaguely like a tiny fish, with a prominent head and a long tail. The neck region of a vertebrate pharyngula also has a series of pharyngeal pouches, or tiny ridges, which recapitulationists misleadingly refer to as gill slits. Although in fish embryos these actually go on to form gills, in other vertebrates they develop into various other head structures such as the inner ear and parathyroid gland (Lehman, 1987) The embryos of mammals, birds and reptiles never possess gills. I do not agree with Wells on many things, but randman seems to believe Wells is correct in anything dealing with Haeckel and, therefore, any arguments eminating from Haeckel's "deception". So, if Wells is a major source of information, then how can his terminology be good in one instance(red) and not in another(green)? Now, Wells has a problem with gill slits. I am sure he also has a problem with gill pouches since, as he states, these terms falsely give the idea that recapitulation is true. Well, as stated by Mayr--
What is recapitulated are always particular structures, but never the whole adult form of the ancestor. and...
Thus the "useless" [structures] are recapitulated b/c they have the vital function of being embryonic organizers of later developing structures. This is the same reason why all terrestrial vertebrates (tetrapods) develop gill arches at a certain stage in their ontogeny. These gill-like structures are never used for breathing, but instead are drastically restructured during the later ontogeny and give rise to many structures in the neck region of reptiles, birds and mammals. The evident explanation is that the genetic developmental program has no way of eliminating the ancestral stages of development and is forced to modify them during the subsequent steps of development in order to make them suitable for the new life-form of the organism. The anlage of the ancestral organ now serves as a somatic program for the ensuing development of the resructured organ. Mayr, Ernst. What Evolution Is. Basic Books, USA. 2001. pp. 28-30. So, is the whole argument here what we call homologous embryonic structures or the existance of these structures themselves? In the case of the later, PubMed alone provides 184 scientific articles dealing with pharyngeal pouches. (Okabe and Graham's paper on the origin of the parathyroid is listed.) So, since "science is what scientists do" (Judge Overton), pharyngeal pouches, no matter what you call them, either exist in vertebrate embryos or are being falsely proffered by some grand conspiracy propogated by almost every institution of higher learning in the US. If the problem is the former, then we need to determine why these structures are called what they are called. During the Scala Naturae days prior to the modern synthesis, Haeckel and von Baer fought over the "true meaning" behind how and why embryos develop the way they do. von Baer said that organisms develop from a more general body plan to a more specific body plan--"There is gradually taking place a transition form something homogeneous and general to something heterogeneous and special." However, this explanation was incomplete. So, staying true to the Scala Naturae, Haeckel came up with his recapitulation stuff in order to explain that the organisms, even at the embryonic stages, are becoming more "perfected" as we go up the ladder from fish to amphibians to reptiles to man. (We need to note that the whole Scala Naturae idea was probably the earliest form of ID.) So, it makes sense to call the pharyngeal pouches, gill pouches or gill slits, if one is using the whole Scala Naturae context. Interesting how the use of the terminology gill pouches/slits came from an idea that was proffered in order to bolster the idea of an intelligent creator!?! Now, I do not refer to these structures as gill pouches/slits in my classes. I refer to them as pharyngeal pouches b/c that term seems more appropriate when dealing with the tetrapods. I have read some articles with the branchial terminology reserved for fish. However the terminology is used, the key fact, which seems to escape some people, is that the embryos of all the vertebrates contain homologous structures that are indicative of a "relatively" closer common ancestry for all of the vertebrates. Thanks for reading. I am sure you know all of this already. Please add or correct anything you think is relative. Take care.
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AdminJar Inactive Member |
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