Talk:Recapitulation theory

Barnacles

 * Don't know if this resolves the point about selective pressures, but as an example: Barnacles have two distinct larval stages, the nauplius and the cyprid, before developing into a mature adult. The nauplius is the larval stage of crustaceans, and this finding was the clue for scientists that barnacles are a crustacean. . dave souza, talk 07:51, 16 June 2012 (UTC)


 * Possible useful source: " in 1835 the presence of larval stages of cirripedes was still a matter of dispute among naturalists. Prior to the publication in 1830 of John Vaughan Thompson's account of the developmental history of cirripedes, which pointed out the similarity of barnacle larvae to those of Crustacea, most naturalists had followed Linnaeus and Cuvier in classifying the cirripedes as molluscs because of their external shelly covering and because their mantle cavity contained sea-water (Winsor 1969). Thompson’s sequential observations of the metamorphosis of nauplius and cypris larvae into adult barnacles, reinforced (and reinterpreted) a few years later by Hermann Burmeister (Burmeister 1834), first revealed the developmental stages of these organisms. The consequent sudden shift of the Cirripedia from one branch of the animal kingdom to another—from the Mollusca to the Articulata—indicated to mid-nineteenth century naturalists that a revaluation of the group, based on a systematic and anatomical comparison intra se and with other Crustacea, was needed. . . . Darwin's evolutionary interpretation of the meaning of classification explains why he readily adopted embryology as a methodological tool for revealing homologies. . . . . . ." dave souza, talk 07:53, 16 June 2012 (UTC)

Behavioral development
removed behaviorial development from fields in which recapitulation theory is seen as plausible. The citation does not match the assertion. The citation is from someone who incorrectly believes that recapitulation theory is plausible in anatomy and then argues that it's *not* correct in behavioral development.

In fact, recapitulation theory is pretty discredited in the field of early childhood development. I'll add some text when I get citations


 * like Behavioral Development,

Roadrunner (talk) 06:53, 11 October 2012 (UTC)

Theory still cited as fact in science writing
Elizabeth Royte in her book, The Tapir's Morning Bath, assumes this theory as fact when describing the development of her baby during her pregnancy while on Barro Colorado Island. — Preceding unsigned comment added by 98.232.150.32 (talk) 02:27, 24 November 2012 (UTC)
 * Hi! The talk page is for discussing the article, not the subject. Is there anything in the article you would like to discuss here? With friendly regards,  Lova Falk     talk   10:20, 24 November 2012 (UTC)

Ernst Haeckel was utterly discredited by Ken Miller of Harvard in 1993. The article should say so. — Preceding unsigned comment added by 24.89.229.157 (talk) 05:46, 24 May 2019 (UTC)

Tagged as too narrow
The article is tagged as being too narrowly focussed on the 19th century biological theory (Haeckel et al), but in fact both the lead and the body of the article seem quite gracefully to discuss both the discredited biological theory and the existence of newer theories in other fields. Any reason not to remove the tag? Chiswick Chap (talk) 12:59, 9 May 2013 (UTC)

Assessment comment
Substituted at 04:01, 30 April 2016 (UTC)

Article scope and coherence
The article correctly states that the embryological theory is (long) outdated. But then it goes on to conflate completely unrelated theories just because they also involve the concept of "recapitulation". This is completely irrational. The article needs to make up its mind if it is about embryology, or about the concept of "recapitulation" in general. In any case it cannot use the findings of embryology to argue that any proposal in, say, psychology or linguistics is or isn't valid. The "origins" of the embryological theory do not lie with Psamtik, this is complete nonsense. And if the article wants to discuss glottogony as its main topic, because apparently there lie the "origins" of the idea, then it cannot lead with the statement that a certain embryological theory is false. --dab (𒁳) 08:16, 16 September 2017 (UTC)


 * Yes, the article should certainly focus on Haeckel's embryology, and we should cut down the non-biological material to 'and also' status, when we're sure it derives from the biology, or remove it altogether if it doesn't. Chiswick Chap (talk) 08:23, 16 September 2017 (UTC)


 * That would seem best. Although I have to say Embryo drawing already covers the embryo thing better than this page. Some WP:CFORK to clean up there.
 * A matter for the other article, but some overlap is reasonable as the drawing aspect is different from the theory aspect. Chiswick Chap (talk) 08:51, 16 September 2017 (UTC)
 * The non-embryological stuff does appear to have some validity, but it isn't presented properly. At least the "art criticism" stuff doesn't seem noteworthy though.
 * Thank you. It is reliably cited. Chiswick Chap (talk) 08:51, 16 September 2017 (UTC)
 * I also note that this was essentially a "religion vs. evolution" debate in the early 20th century, and while Haeckel's proposals do appear to have been gone too far, the "controversy" was fuelled by accusations of fraud from the side of religious conservatives (Jesuits) who tried to rescue the non-evolutionary view of biology. Since evolution no longer hinges on this (or never has), the ideological attacks on Haeckel, just like Haeckel's views themselves, do seem mostly of historical interest.
 * Notability is not temporary. Chiswick Chap (talk) 08:51, 16 September 2017 (UTC)
 * So it does appear to me the article overreaches in shooting down "recapitulation" as a universal law in embryology, to the point of ignoring that it still holds as a perfectly valid heuristic.
 * See below. Chiswick Chap (talk) 08:51, 16 September 2017 (UTC)
 * This is made plain by the quote in the "contemporary status" section, which matter-of-factly states Embryos do reflect the course of evolution. It's not a universal law, and it's easy to find counter-examples, but well, in general they just do. So as long as "recapituation" doesn't imply any more than that, it's just a true and perfectly relevant observation, and not "biological mythology". --dab (𒁳) 08:35, 16 September 2017 (UTC)
 * This isn't a forum and we shouldn't get into an object-level discussion of the history here. There is however no doubt that evolution applies just as much to the embryo as to the adult, and indeed the main thrust of evolutionary developmental biology (evidenced by tens of thousands of papers) is that the adult body is reshaped by changes that apply during development (how could they not be). For example (there are plenty of other mechanisms), bodies can become longer by changing the timing (heterochrony) of signals turning on or off the creation of body segments. Such changes are genetic, but they reshape the pattern and course of embryology and then the structure of the adult. This comprehensively rebuts Haeckel's view. Chiswick Chap (talk) 08:51, 16 September 2017 (UTC)
 * I don't see why you are telling me "WP:NOTAFORUM" when I am pointing out specific problems with the article content. I am pointing out that the article is preaching, and that it is needlessly polemic about a long-dead controversy, and you reply by "notability is not temporary". This doesn't make sense. You tell me "not a forum" but immediately go onto an incoherent tangent on how "evolution applies to the embryo". I am sorry, our initial interaction seemed constructive but this behaviour confuses me.
 * I am not trying to defend Haeckel's views, indeed my initial point was that it isn't clear to what extent this page is supposed to be about Haeckel specifically, or even about embryology.
 * The page fails to link the article on von Baer's laws (embryology) altogether. Is "recapitulation theory" as treated in this article strictly about Meckel and Haeckel, or would it include more moderate statements such as von Baer's,
 * "The embryo successively adds the organs that characterize the animal classes in the ascending scale. When the human embryo, for instance, is but a simple vesicle, it is an infusorian; when it has gained a liver, it is a mussel; with the appearance of the osseous system, it enters the class of fishes; and so forth, until it becomes a mammal and then a human being"
 * Note that this paragraph was written to reject Meckel. At the same time it is exactly what I would describe as "ontogeny recapitulates phylogeny", i.e. "characters in the embryo are formed in top-to-bottom sequence, first from those of the largest and oldest taxon, the phylum, then in turn class, order, family, genus, and finally species"
 * If the above is a refutation of "recapitulation theory", then this page needs to make a lot clearer on what exactly does and does not count as "recapitulation". --dab (𒁳) 15:03, 16 September 2017 (UTC)
 * Gosh, let's take this slowly: it will take time and work. I think I may have misunderstood your drift, in that case, as you seemed to be saying something else: but you certainly made many different points, some of which are certainly correct, others I think not. We agree, I think, that this is absolutely about Haeckel's theory, and everything else is either subsidiary or off-topic, which is why I have already (with, I believe, your full assent) cut down the non-Haeckel material. I think we can readily agree that the article can focus further on what recapitulation theory is; and hence, who other than Haeckel did in fact contribute to it, disagree with it, or (eventually) refute it. Since you argued and indeed edited earlier to the effect that the theory was not "discredited" (it is), I have pointed out why, which indicates that the article needs to say more, with detailed evidence, to that effect - it certainly isn't a tangent, and it's highly coherent. At the risk of spelling things out to those who already know, since evolution affects the embryo at all stages of its development, the embryo cannot remain as it was at (say) the fish or the chicken "stage", with "higher" Haeckelian stages added on: instead, the whole process gets rejigged and every stage of the embryo potentially gets reworked, destroying more and more of the "recapitulation". So it's absolutely relevant. But you are right, and the article needs to have a step-by-step history of how Haeckel was proven wrong: I'll see to it. On von Baer (who was not a recapitulationist), I think the suggestion of a mention is wise, if only to point out the differences - Haeckel arguing for a linear sequence ("man" being N stages on from "fish" and one or two on from "bird"), von Baer for a diverging tree ("man" and "bird" becoming ever more dissimilar from their ancestors) - now linked, thanks for the suggestion. Chiswick Chap (talk) 17:16, 16 September 2017 (UTC)