Embryo drawings

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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.

1 History
- 1.1 Place in textbooks
2 See also
3 References

[edit] History

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.

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.

[edit] 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.

[edit] See also

Recapitulation theory (ontogeny recapitulates phylogeny)

[edit] 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