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Encyclopedia > Embryo drawings

The term embryo drawings refers to illustrations of embryos. In particular, the term often refers to a specific series of embryo drawings produced by Ernst Haeckel, with the aim of comparing embryos of different classes. These drawings are discussed herein. Categories: Biology stubs | Developmental biology ... Ernst Haeckel. ... Classes can refer to: social class scientific classification class (object-oriented programming) a subject in school see also class. ...

Contents

History

Ernst Haeckel's embryo drawings.
Ernst Haeckel's embryo drawings.

In 1866, Ernst Haeckel claimed that members of all vertebrate classes pass through virtually identical early embryonic stages. To illustrate this, he published side-by-side drawings of embryos of various vertebrates (namely human, rabbit, calf, hog, chick, tortoise, salamander, and fish) at corresponding stages of development. Haeckel used his depictions as evidence for both common descent and his now-discredited recapitulation theory. Download high resolution version (915x800, 187 KB)Embryo drawings drawn by Haeckel in 1866 for his Recapitulation theory. ... Download high resolution version (915x800, 187 KB)Embryo drawings drawn by Haeckel in 1866 for his Recapitulation theory. ... Ernst Haeckel. ... 1866 (MDCCCLXVI) is a common year starting on Monday of the Gregorian calendar or a common year starting on Wednesday of the 12-day-slower Julian calendar. ... Ernst Haeckel. ... Classes and Clades See below Vertebrata is a subphylum of chordates, specifically, those with backbones or spinal columns. ... A group of organisms is said to have common descent if they have a common ancestor. ... The theory of recapitulation, also called the biogenetic law or ontogeny recapitulates phylogeny, is a theory in biology which attempts to explain apparent similarities between humans and other animals. ...


Studies in the past century have shown that while embryos of different classes certainly do show similarities in their early stages, there are also many differences. Haeckel appears to have deliberately "fudged" his drawings in order to de-emphasize the differences and exaggerate the similarities, thus providing better evidence for his arguments.


The intentional "fraud" now evident in Haeckel's drawings is used by some creationists as evidence against common descent and evolution. However, biologists point out that vertebrate embryos do in fact share many fundamental similarities in the phylotypic stage; the evidence is real but it exists in the embryos, not in Haeckel's drawings.


Concerning Haeckel's theory of recapitulation, some creationists have used biologists' rejection of it as evidence against evolution. However, the biologists point out that the discrediting of recapitulation does not affect the credibility of evolutionary theory because recapitulation was based upon evolutionary theory, not the other way around. Creationism is generally the belief that the universe was created by a deity, or alternatively by one or more powerful and intelligent beings. ...


Place in textbooks

Haeckel's drawings have been reproduced in a wide range of textbooks. In 2000, Harvard University professor Stephen Jay Gould commented on the continued use of Haeckel's embryo drawings in textbooks. He wrote: "We do, I think, have the right to be both astonished and ashamed by the century of mindless recycling that has led to the persistence of these drawings in a large number, if not a majority, of modern textbooks." Many modern textbooks now contain photographs to show the similarities in embryo development among related species. This article is about the year 2000. ... Harvard University (incorporated as The President and Fellows of Harvard College) is a private university in Cambridge, Massachusetts. ... Stephen Jay Gould Stephen Jay Gould (September 10, 1941 – May 20, 2002) was an American paleontologist, evolutionary biologist, historian of science, and professor. ...


See also

The theory of recapitulation, also called the biogenetic law or ontogeny recapitulates phylogeny, is a theory in biology which attempts to explain apparent similarities between humans and other animals. ...

References

  • Haeckel, E. 1899. Riddle of the Universe at the Close of the Nineteenth Century. Cited at http://www.ucmp.berkeley.edu/history/haeckel.html.
  • Division of Biology and Medicine, Brown University, Evolution and Development I: Size and shape, http://biomed.brown.edu/Courses/BIO48/30.S&S.HTML
  • Myers, P.Z. 2003. Wells and Haeckel's Embryos. http://www.talkorigins.org/faqs/wells/haeckel.html
  • Richardson, M. K. 1995. Heterochrony and the phylotypic period. Dev. Biol. 172: 412 - 421.
  • Flock of Dodos and Haeckel's Embryos http://designparadigm.googlepages.com/haeckel

  Results from FactBites:
 
Embryo Images Online- Credits (340 words)
Embryo Images Normal and Abnormal Mammalian Development is a tutorial that uses scanning electron micrographs (SEMs) as the primary resource to teach mammalian embryology.
All of the images have a legend that indicates the age of the embryo.
The line drawings have been used with permission from Lippincott Williams and Wilkins and are from the 6th and 7th editions of Langman's Medical Embryology by T.W. Sadler.
Introduction (0 words)
He claims that he knew that the drawings of embryos presented in textbooks were false because he was a developmental biologist.
Many of the general "differences" in early embryo development that Wells mentions are a result of organization due to the yolk size rather than being specific differences in the basic body-plan of the embryo (Arendt and NĂ¼bler-Jung, 1999).
Embryos do reveal phylogenetic information in terms of specific shared features, shared early developmental features such as the formation of a germinal disc and primitive streak in all amniotes or the neural crest cells of all vertebrates.
  More results at FactBites »

 
 

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