Von Baer's laws (embryology)

Embryology theories of Ernst Haeckel (following Meckel) and Karl Ernst von Baer compared. Von Baer denied any recapitulation of whole adult forms, though individual structures might be recapitulated.

In developmental biology, von Baer's laws of embryology (or laws of development) are four rules proposed by Karl Ernst von Baer to explain the observed pattern of embryonic development in different species.[1]

von Baer formulated the laws in his book On the Developmental History of Animals (German: Über Entwickelungsgeschichte der Thiere), published in 1828, while working at the University of Königsberg. He specifically intended to rebut Johann Friedrich Meckel's 1808 recapitulation theory. According to that theory, embryos pass through successive stages that represent the adult forms of less complex organisms in the course of development, and that ultimately reflects scala naturae (the great chain of being).[2] von Baer believed that such linear development is impossible. He posited that instead of linear progression, embryos started from one or a few basic forms that are similar in different animals, and then developed in a branching pattern into increasingly different organisms. Defending his ideas, he was also opposed to Charles Darwin's 1859 theory of common ancestry and descent with modification, and particularly to Ernst Haeckel's revised recapitulation theory with its slogan "ontogeny recapitulates phylogeny".[3][4] Darwin was however broadly supportive of von Baer's view of the relationship between embryology and evolution.

The laws

Von Baer described his laws in his book Über Entwickelungsgeschichte der Thiere. Beobachtung und Reflexion published in 1828.[5] They are a series of statements generally summarised into four points, as translated by Thomas Henry Huxley in his Scientific Memoirs:[6]

  1. The more general characters of a large group appear earlier in the embryo than the more special characters.
  2. From the most general forms the less general are developed, and so on, until finally the most special arises.
  3. Every embryo of a given animal form, instead of passing through the other forms, rather becomes separated from them.
  4. The embryo of a higher form never resembles any other form, but only its embryo.

Description

Von Baer discovered the blastula (the early hollow ball stage of an embryo) and the development of the notochord (the stiffening rod along the back of all chordates, that forms after the blastula and gastrula stages). From his observations of these stages in different vertebrates, he realised that Johann Friedrich Meckel's recapitulation theory must be wrong. For example, he noticed that the yolk sac is found in birds, but not in frogs. According to the recapitulation theory, such structures should invariably be present in frogs because they were assumed to be at a lower level in the evolutionary tree. Von Baer concluded that while structures like the notochord are recapitulated during embryogenesis, whole organisms are not.[7] He asserted that (as translated):

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.[8]

In terms of taxonomic hierarchy, according to von Baer, 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.[7]

Reception

The laws received a mixed appreciation. While they were criticised in detail, they formed the foundation of modern embryology.[1]

Charles Darwin

The most important supporter of von Baer's laws was Charles Darwin. Darwin came across von Baer's laws from the work of Johannes Peter Müller in 1842, and realised that it was a support for his own theory of descent with modification.[9] Darwin was a critique of the recapitulation theory and agreed with von Baer that an adult animal is not reflected by an embryo of another animal, and only embryos of different animals appear similar.[10] He wrote in his Origin of Species (first edition, 1859):

[The] adult [animal] differs from its embryo, owing to variations supervening at a not early age, and being inherited at a corresponding age. This process, whilst it leaves the embryo almost unaltered, continually adds, in the course of successive generations, more and more difference to the adult. Thus the embryo comes to be left as a sort of picture, preserved by nature, of the ancient and less modified condition of each animal. This view may be true, and yet it may never be capable of full proof.[11]

Darwin also said:

It has already been casually remarked that certain organs in the individual, which when mature become widely different and serve for different purposes, are in the embryo exactly alike. The embryos, also, of distinct animals within the same class are often strikingly similar: a better proof of this cannot be given, than a circumstance mentioned by Agassiz, namely, that having forgotten to ticket the embryo of some vertebrate animal, he cannot now tell whether it be that of a mammal, bird, or reptile.[12]

Darwin's attribution to Louis Agassiz was a mistake,[13] and was corrected in the third edition as von Baer.[14] He further explained in the later editions of Origin of Species (from third to sixth editions), and wrote:

It might be thought that the amount of change which the various parts and organs [of vertebrates] undergo in their development from the embryo to maturity would suffice as a standard of comparison; but there are cases, as with certain parasitic crustaceans, in which several parts of the structure become less perfect, so that the mature animal cannot be called higher than its larva. Von Baer's standard seems the most widely applicable and the best, namely, the amount of differentiation of the different parts (in the adult state, as I should be inclined to add) and their specialisation for different functions.[15][16]

Even so, von Baer was a vociferous anti-Darwinist, although he believed in the common ancestry of species.[17] Devoting much of his scholarly effort to criticising natural selection, his criticism culminated with his last work Über Darwins Lehre ("On Darwin's Doctrine"), published in the year of his death in 1876.[18]

Later biologists

The British zoologist Adam Sedgwick studied the developing embryos of dogfish and chicken, and in 1894 noted a series of differences, such as the green yolk in the dogfish and yellow yolk in the chicken, absence of embryonic rim in chick embryos, absence of blastopore in dogfish, and differences in the gill slits and gill clefts. He concluded:

There is no stage of development in which the unaided eye would fail to distinguish between them with ease... A blind man could distinguish between them.[19]

Modern biologists still debate the validity of the laws. In one line of argument, it is said that although every detail of von Baer's law may not work, the basic assumption that early developmental stages of animals are highly conserved is a biological fact.[20] But an opposition says that there are conserved genetic conditions in embryos, but not the genetic events that govern the development.[21] One example on the problem of von Baer's law is the formation of notochord before heart. This is due to the fact that heart is present in many invertebrates, which never have notochord.[22]

See also

References

  1. ^ a b Abzhanov, Arhat (2013). "von Baer's law for the ages: lost and found principles of developmental evolution". Trends in Genetics. 29 (12): 712–722. doi:10.1016/j.tig.2013.09.004. PMID 24120296. S2CID 9158143.
  2. ^ Opitz, John M.; Schultka, Rüdiger; Göbbel, Luminita (2006). "Meckel on developmental pathology". American Journal of Medical Genetics Part A. 140A (2): 115–128. doi:10.1002/ajmg.a.31043. PMID 16353245. S2CID 30513424.
  3. ^ Garstang, Walter (1922). "The Theory of Recapitulation: A Critical Re-statement of the Biogenetic Law". Journal of the Linnean Society of London, Zoology. 35 (232): 81–101. doi:10.1111/j.1096-3642.1922.tb00464.x.
  4. ^ Løvtrup, Søren (1978). "On von Baerian and Haeckelian Recapitulation". Systematic Zoology. 27 (3): 348–352. doi:10.2307/2412887. JSTOR 2412887.
  5. ^ Baer, Karl Ernst von (1828). Über Entwickelungsgeschichte der Thiere. Beobachtung und Reflexion. Königsberg: Bei den Gebrüdern Bornträger. doi:10.5962/bhl.title.6303.
  6. ^ Huxley, Thomas Henry (1853). Henfrey, Arthur (ed.). Scientific memoirs, selected from the transactions of foreign academies of science, and from foreign journals. Natural history. Taylor and Francis. doi:10.5962/bhl.title.28029.
  7. ^ a b Matthen, Mohan; Stephens, Christopher (2007). Philosophy of Biology. Amsterdam: Elsevier. pp. 444–445. ISBN 978-0-080-47124-2.
  8. ^ Ospovat, D. (1976). "The influence of Karl Ernst von Baer's embryology, 1828–1859: A reappraisal in light of Richard Owen's and William B. Carpenter's "Palaeontological application of 'von Baer's law'"". Journal of the History of Biology. 9 (1): 1–28. doi:10.1007/BF00129171. PMID 11615631. S2CID 40800347.
  9. ^ Gilbert, Scott F. (2000). Developmental Biology. Sinauer Associates. pp. Online. ISBN 978-0878932436.
  10. ^ Barnes, M. Elizabeth (2014). "Karl Ernst von Baer's Laws of Embryology". The Embryo Project Encyclopedia. Retrieved 2020-10-04.
  11. ^ Darwin, Charles (1859). On the Origin of Species. London: John Murray. p. 338.
  12. ^ Darwin, Charles (1859). On the Origin of Species. London: John Murray. pp. 438–439.
  13. ^ Rogers, James Allen (1973). "The Reception of Darwin's Origin of Species by Russian Scientists". Isis. 64 (4): 484–503. doi:10.1086/351177. JSTOR 229645. PMID 4593473. S2CID 36129302.
  14. ^ Darwin, Charles (1861). The Origin of Species (3 ed.). London: John Murray. pp. 470–471.
  15. ^ Darwin, Charles (1861). On the Origin of Species. John Murray. p. 133.
  16. ^ Darwin, Charles (1872). The Origin of Species (6 ed.). London: John Murray. p. 97.
  17. ^ Dagg, Joachim L.; Derry, J. F. (2020). "Charles Darwin did not mislead Joseph Hooker in their 1881 Correspondence about Leopold von Buch and Karl Ernst von Baer". Annals of Science. 77 (3): 349–365. doi:10.1080/00033790.2020.1790659. PMID 32755351. S2CID 221016353.
  18. ^ Vucinich, Alexander (1988). Darwin in Russian Thought. Berkeley: University of California Press. p. 93. ISBN 978-0-52-006283-2.
  19. ^ Sedgwick, Adam (1894). "Memoirs: On the Law of Development commonly known as von Baer's Law; and on the Significance of Ancestral Rudiments in Embryonic Development". Journal of Cell Science. s2-36 (141): 35–52. doi:10.1242/jcs.s2-36.141.35.
  20. ^ Garfield, David A.; Wray, Gregory A. (2009). "Comparative embryology without a microscope: using genomic approaches to understand the evolution of development". Journal of Biology. 8 (7): 65. doi:10.1186/jbiol161. PMC 2736668. PMID 19664180.
  21. ^ Kalinka, Alex T.; Tomancak, Pavel (2012). "The evolution of early animal embryos: conservation or divergence?". Trends in Ecology & Evolution. 27 (7): 385–393. Bibcode:2012TEcoE..27..385K. doi:10.1016/j.tree.2012.03.007. ISSN 1872-8383. PMID 22520868.
  22. ^ Løvtrup, Søren (1987). "Phylogenesis, ontogenesis and evolution". Italian Journal of Zoology. 54 (3): 199–208. doi:10.1080/11250008709355584.

Read other articles:

American politician (1914–1986) Al UllmanChair of the House Ways and Means CommitteeIn officeDecember 10, 1974 – January 3, 1981Preceded byWilbur MillsSucceeded byDan RostenkowskiChair of the House Budget CommitteeIn officeJuly 12, 1974 – January 3, 1975Preceded byPosition establishedSucceeded byBrock AdamsCo-Chair of the Joint Budget Control CommitteeIn officeOctober 27, 1972 – April 18, 1973Serving with Jamie WhittenPreceded byPosition establishedS...

 

 

American legislative district Maryland's legislative district 34BRepresentspart of Harford CountyDelegate(s)Susan K. McComas (R)Registration43.4% Republican34.1% Democratic21.0% unaffiliatedDemographics78.0% White8.4% Black/African American0.2% Native American4.4% Asian0.0% Hawaiian/Pacific Islander2.0% Other race7.0% Two or more races5.4% HispanicPopulation (2020)44,265Voting-age population34,400Registered voters32,003 Maryland Hous...

 

 

Universitas Dankook단국대학교 (檀國大學校)Moto자립·자주·구국Moto dalam bahasa InggrisSelf-relianceIndependenceNational salvationJenisUniversitas swastaDidirikan3 November 1947PresidenHo-sung ChangSarjanaKampus Jukjeon: 10,466Kampus Cheonan: 11,686MagisterKampus Jukjeon: 3,648Kampus Cheonan: 3,987LokasiKampus Jukjeon: Yongin, Gyeonggi, Korea SelatanKampus Cheonan: Cheonan,Chungnam, Korea SelatanKampusUrbanWarnaBiru  MaskotBeruang[1]Situs webdankook.ac.krBerk...

Berita Hiburan BeijingTipeKoran harianPenerbitGrup Harian BeijingDidirikan4 Januari 1981Pandangan politikKomunisme, Sosialisme dengan karakteristik TiongkokBahasaAksara Han (sederhana)Berhenti publikasi1 Januari 2018 Berita Hiburan Beijing (diterjemahkan dalam bahasa Inggris menjadi Beijing Star Daily[1]) merupakan koran komprehensif yang diterbitkan oleh Harian Beijing. Sebelumnya koran ini bernama Berita Drama dan Film yang didirikan oleh Asosiasi Sastra dan Seni Beijing pada 4 Janu...

 

 

En hydrologie, le VCN3, ou volume consécutif minimal pour 3 jours, est le débit minimal ou débit d’étiage des cours d'eau enregistré pendant 3 jours consécutifs sur le mois considéré. C'est une valeur comparée par rapport aux valeurs historiques de ce même mois. Le VCN3 permet de « caractériser une situation d'étiage sévère sur une courte période »[1]. Articles connexes QIX (« quantité instantanée maximale ») QJX (« quantité journalière maxim...

 

 

Chronologies Données clés 1497 1498 1499  1500  1501 1502 1503Décennies :1470 1480 1490  1500  1510 1520 1530Siècles :XIIIe XIVe  XVe  XVIe XVIIeMillénaires :-Ier Ier  IIe  IIIe Chronologies thématiques Art Architecture, Arts plastiques (Dessin, Gravure, Peinture et Sculpture), (), Littérature () et Musique (Classique)   Ingénierie (), Architecture et ()   Politique   Religion (,)   Science () et Santé et mé...

1950 film by Robert McKimson Pop 'Im Pop!A still of a scene of Pop 'Im Pop! animated by J.C. Melendez.Directed byRobert McKimsonStory byWarren Foster[1]StarringMel BlancMusic byCarl StallingAnimation byCharles McKimsonRod ScribnerPhil DeLaraManuel PerezJ.C. MelendezLayouts byCornett WoodBackgrounds byRichard H. ThomasColor processTechnicolorDistributed byWarner Bros. PicturesRelease dateOctober 28, 1950Running time7:14LanguageEnglish Pop 'Im Pop! is a 1950 Warner Bros. Looney Tunes th...

 

 

County in Michigan, United States County in MichiganKeweenaw CountyCountyKeweenaw County Courthouse (built 1866) in Eagle RiverLocation within the U.S. state of MichiganMichigan's location within the U.S.Coordinates: 47°29′N 88°10′W / 47.48°N 88.16°W / 47.48; -88.16Country United StatesState MichiganFoundedMarch 11, 1861[1][2]Named forKeweenaw BaySeatEagle RiverLargest settlementMohawk (CDP)Ahmeek (village)Area • Total5,966...

 

 

Kup kralja Aleksandra 1924 Competizione Kup kralja Aleksandra Sport Calcio Edizione 1ª Organizzatore JNS Date dal 24 agosto 1924al 4 ottobre 1924 Luogo Regno dei Serbi, Croati e Sloveni Partecipanti 7 Formula Eliminazione diretta Risultati Vincitore Zagabria XI(1º titolo) Secondo Spalato XI Semi-finalisti Lubiana XISubotica XI Cronologia della competizione 1925 Manuale La Kup kralja Aleksandra 1924., in serbo Куп краља Александра 1924. (in italiano Coppa del re Al...

Голубянки Самец голубянки икар Научная классификация Домен:ЭукариотыЦарство:ЖивотныеПодцарство:ЭуметазоиБез ранга:Двусторонне-симметричныеБез ранга:ПервичноротыеБез ранга:ЛиняющиеБез ранга:PanarthropodaТип:ЧленистоногиеПодтип:ТрахейнодышащиеНадкласс:ШестиногиеКласс...

 

 

هذه المقالة تحتاج للمزيد من الوصلات للمقالات الأخرى للمساعدة في ترابط مقالات الموسوعة. فضلًا ساعد في تحسين هذه المقالة بإضافة وصلات إلى المقالات المتعلقة بها الموجودة في النص الحالي. (مارس 2023) يفتقر محتوى هذه المقالة إلى الاستشهاد بمصادر. فضلاً، ساهم في تطوير هذه المقالة م...

 

 

Football match2017 CAF Super Cup2017 Total CAF Super Cup Mamelodi Sundowns TP Mazembe 1 0 Date18 February 2017 (2017-02-18)VenueLoftus Versfeld Stadium, PretoriaRefereeGehad Grisha (Egypt)← 2016 2018 → The 2017 CAF Super Cup (officially the 2017 Total CAF Super Cup for sponsorship reasons)[1] was the 25th CAF Super Cup, an annual football match in Africa organized by the Confederation of African Football (CAF), between the winners of the previous season's t...

2016年美國總統選舉 ← 2012 2016年11月8日 2020 → 538個選舉人團席位獲勝需270票民意調查投票率55.7%[1][2] ▲ 0.8 %   获提名人 唐納·川普 希拉莉·克林頓 政党 共和黨 民主党 家鄉州 紐約州 紐約州 竞选搭档 迈克·彭斯 蒂姆·凱恩 选举人票 304[3][4][註 1] 227[5] 胜出州/省 30 + 緬-2 20 + DC 民選得票 62,984,828[6] 65,853,514[6]...

 

 

Army of ArkansasActive1863–1865Country United States of AmericaBranch United States ArmyTypeField armyEngagementsAmerican Civil WarCommandersNotablecommandersFrederick SteeleJoseph J. ReynoldsMilitary unit The Army of Arkansas was a Union Army that served in the Trans-Mississippi Theater during the American Civil War. This force functioned exclusively in the state of Arkansas. History The Army of Arkansas was created on July 27, 1863, with Major General Frederick Steele in command...

 

 

Season of television series The Face ThailandSeason 2Promotional posterNo. of episodes13ReleaseOriginal networkChannel 3Original release17 October 2015 (2015-10-17) –9 January 2016 (2016-01-09)Season chronology← PreviousSeason 1Next →Season 3List of episodes The Face Thailand season 2 began audition on 2 August 2015 at Royal Paragon Hall in Siam Paragon in Bangkok. Lukkade Metinee was reprised their roles as coaches again. Bee Namthip and Cris Horwang was the n...

German bank that specialises in real estate and public sector financing Deutsche PfandbriefbankCompany typePublic (Aktiengesellschaft)Traded asFWB: PBBSDAX componentIndustryBankingPredecessorHypo Real EstateHeadquartersGarching, Munich (district), Upper Bavaria, Germany Deutsche Pfandbriefbank AG is a German bank that specialises in real estate and public sector financing.[1] As of 2016, it is a constituent of the SDAX trading index of German small-cap companies.[2] It is...

 

 

Part of the worldwide Catholic Church Not to be confused with Catholic Church in England and Wales. Westminster Cathedral, London, England. Part of a series on theCatholic Church by country Africa Algeria Angola Benin Botswana Burkina Faso Burundi Cameroon Cape Verde Central African Republic Chad Comoros Democratic Republic of the Congo Republic of the Congo Djibouti Egypt Equatorial Guinea Eritrea Eswatini Ethiopia Gabon Gambia Ghana Guinea Guinea-Bissau Ivory Coast Kenya Lesotho Liberia Lib...

 

 

World Wide Fund for NaturePendiriPangeran Bernhard dari Lippe-Biesterfeld Julian Huxley [1]Max NicholsonPeter ScottGuy MountfortGodfrey A. Rockefeller [2]JenisLembaga amanah amalDidirikan29 April 1961(Kantor pertama dibuka September 1961 di Morges, Swiss)LokasiGland, SwissOrang pentingPresiden: Yolanda KakabadseWilayah layananSeluruh duniaFokusEnvironmentalismeMetodeLobi, penelitian, konsultasiPendapatan€525 juta (2010) [3]SloganFor a Living PlanetSitus resmiwwf.orgp...

A water wave traveling upstream a river or narrow bay because of an incoming tide A bore in Morecambe Bay, in the United Kingdom Video of the Arnside Bore, in the United Kingdom The tidal bore in Upper Cook Inlet, in Alaska A tidal bore,[1] often simply given as bore in context, is a tidal phenomenon in which the leading edge of the incoming tide forms a wave (or waves) of water that travels up a river or narrow bay, reversing the direction of the river or bay's current. It is a stron...

 

 

Flag The article's lead section may need to be rewritten. Please help improve the lead and read the lead layout guide. (August 2017) (Learn how and when to remove this message) MoraviaUseOther DesignHistorical flag of Moravia (the heraldic flag with Moravian Eagle), recommended by Czech Vexillological Society MoraviaUseOther DesignFlag of Moravia as bicolor with gold-red checked eagle (from 2007), by Moravian National Community An official version of the flag of Moravia, unlike the provincial...