Why are Haeckel's drawings being taught in school?

"Haeckel based his biogenetic law on the flawed premise that evolutionary change occurs by successively adding stages onto the end of an unaltered ancestral ontogeny, compressing the ancestral ontogeny into earlier developmental stages." This section also talks about von Baer and makes the point that he wasn't exactly right either. Freeman doesn't discuss Haeckel or von Baer and never even mentions them in the book. However, he does provide two pictures from Richardson (from Anatomy and Embryology) that show human and chicken embryos clearly having gill pouches and tails. If you feel better, you can call them pharyngeal pouches. Again, no mention of Haeckel or von Baer, but shows the similarities between a human and bird embryo. Pictures are from Dwight Kuhn (avian embryo) and Lennart Nilsson (human embryo from A Child is Born). Points out gill pouches and postanal tail. On the following page (425), they talk about how the "theory of recapitulation is an overstatement" and that "many embryologists in the late nineteenth century proposed the extreme view that ontogeny recapitulates phylogeny". (Italics originally in quotations.) Shows drawings comparing fish, tortoise, chicken and human embryos (by someone named Molly Babich). The drawings are pathetic renditions of actual photographs. They look cartoonish. They only show two stages of development and are not labeled in any helpful way. The text doesn't mention Haeckel or von Baer which might make sense since our biology curriculum is "an inch deep and a mile wide". The paragraph that points to these drawings is equally disappointing. "Each embryo develops a tail, buds that become limbs, and pharyngeal pouches (which contain the gills of fish and amphibians.) The tail remains in most adult vertebrates. Although the structures develop at different rates in different groups of vertebrates, they are homologous. Only adult fish and immature amphibians retain pharyngeal pouches. In humans, the tail disappears by the time of birth, and pharyngeal pouches develop into other structures."This passage sounds like the old "ontogeny recapitulates phylogeny" crap. I do like the last sentence however b/c it leads me to what Ernst Mayr says about this topic. (If anyone has a problem with Ernst Mayr's creds, please feel free to speak up.) I have now shown three textbooks that do a great job with the actual info regarding this whole recapitulation stuff. However, only one mentions the problems with Haeckel and von Baer and it is a college level Zoology text. Campbell's Biology is the usual college freshman biology textbook and is used in high school AP Biology classes. Freeman's Biological Science is the textbook I want to use in my high school classes.I see a problem, that you, randman, have pointed out and I think is a good point--wtf!!! Why is the high school textbook I have to use so worthless on this topic? Someone earlier in this thread made an argument along these lines that I agree with (and if I am wrong, please correct me) that high school textbooks are not thoroughly reviewed and basically churned out for sale. This causes them to rely on old "stock footage" that they just throw in there. The people reviewing these things are made up of high school biology teachers and college professors. Maybe there is pressure to churn these things out without the thorough work necessary for good academics. Clearly, though, the college texts are way better. Why the descrepency?I think it is money. These publishers are businesses that are out to make a profit. The Holt high school Biology text has a bright shiney cover and plenty of color pictures and an unnecessary 1096 pages! And the cost of refitting a high school with biology textbooks is so damn expensive that they use them way past their expiration date or will not change them even if something better comes along to bite them in the arse!Anyway, Haeckel and his substitution of a dog embryo for a human is a piece of science history. I will make it a point to provide my pre-AP students with this example of the self-correcting nature of science--as done by scientists, not book publishers.Have a great Fourth of July! Or as I like to commemerate--Adams, Sr. and T. Jefferson's mutual parting of the ways, and life, in 1826.(Edited to correct "commemerate")(Additional edit to correct some "actual"'s and "vertebrate"'s)This message has been edited by hitchy, 07-03-2005 12:08 AMThis message has been edited by hitchy, 07-03-2005 12:18 AM

Thanks for the back up, Mod.

And the tailbone is the terminal end of the backbone. I suppose, then, that all of the humans that were born with tails were fakes!?! By your understanding, are there any such things as homologous structures?And yes, those are called gill pouches or pharyngeal pouches and I believe Mayr gave a good explanation for their existance in the vertebrates that you might want to read again.Take care.

You mean that no one has given you an acceptable answer to your understanding of the question. Have you ever looked in the textbook by Campbell? I am looking at it right now and there is no mention of Haeckel at all. Nothing in the index. Nothing in the section on evolution.In fact, on page 424, as I have pointed out earlier, there are two pictures comparing human and chicken embryos. Actual pictures! On page 425, there is a paragraph blatantly dismissing the "extreme view that 'ontogeny recapitulates phylogeny.'" Campbell even has the audacity to use a picture from the major source (Richardson) you are using to argue against the textbook's usage.If you don't believe me, take a look for yourself.The claim that Campbell's Biology 5th Ed. teaches Haeckel's claims as fact is false. The text even takes a paragraph to explain that Haeckel's claim of "ontogeny recapitulates phylogeny" is an "extreme view" and "an overstatement". (The text doesn't mention Haeckel by name. It refers to "late nineteenth century embryologists".)I do not have any of the other listed texts at my disposal at the moment. I have used Futuyma's text before, but cannot remember anything about Haeckel in it. The inclusion of Haeckel's drawings in textbooks that are not created by those doing work in the many varied fields related to evolutionary biology is not an indictment of those working in those fields. As a high school biology teacher, I have to tell you that comparative embryology is used in my class as evidence of homology. I use evidence showing the homologies in biochemistry and anatomy as well. After every piece of "evidence for evolution" is presented to my students, I have them come up with a means of falsifying each piece of evidence. There falsifications are then "tested" by them looking up arguments for their falsifications. Since I am lucky enough to have several computers at my disposal, this lesson only takes about a week. The conclusions are always the same--common descent is corroborated by more pieces of individually obtained evidence (individual students doing individual "research") than I could cover by just listing facts to my students. Does that sound like indoctrination? Are my students not encouraged to critically look at the evidence?Which sounds more dogmatic--looking up evidence for a scientific theory or just saying that "[e]volutionism is a form of ideological indoctrination"?Evidence exists regardless of how you perceive it. The evidence for evolution is extraordinary. Science is a self-correcting process that is not nice nor is it democratic. Hypotheses are brutally checked and challanged. Science is a cut-throat business that has no sympathy for weak ideas. There is no voting on whether an idea is right or wrong. The theories involved in biological evolution are still around because they have survived this "weeding out" process. More evidence is found every day that supports evolution. If the evidence did not point to evolution, then evolution would not still be one of the strongest and most robust theories we have in all of science.Also, the misuse of evidence to further a particular viewpoint, such as Haeckel's "ontogeny recapitulates phylogeny", does not dismiss the correct use of that evidence. Tarring the whole biological community with cries of "indoctrination" does not support your viewpoint either. This is a great quote. I honestly like it. I just think it should be applied to the opponents of a robust scientific theory who use false and misapplied claims to further their opinions.

I never said that "Campbell changed and quit using Haeckel's drawings." That would imply that he used them to begin with. Have you ever looked at any of the editions of Campbell's Biology texts?I called you on a mistake. I hardly call that ranting. By the way, my name is hitchy.

Interesting how even Wells uses the terminology-- 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-- and... 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.