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Embryology early development from a phenomenological point of view
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  1. 1. embryologyArgument #4 for Common Descent
  2. 2. embryology: case forEmbryology is the study of the development andformation of embryos.One of Darwin’s arguments for Common Descent isbased on the similarity of embyros of differentorganisms.Darwin writes, “by far the strongest single class of factsin favour of” his theory of Common Descent.
  3. 3. embryology: case forDarwin noticed similarities in the embryos of vertebrateanimals especially during the embryo’s earliest stage ofdevelopment.Because of the similarities he concluded 2 things.
  4. 4. embryology: case for1. It established that organisms had descended from acommon ancestor.He thought that embryos of modern vertebrates aresimilar because they evolved from an ancestral formthat had many of the embryonic features of the modernvertebrates.
  5. 5. embryology: case for2. Darwin thought the observable similarities in differentembryos revealed the ancestors to these organismswould have looked like.Darwin said that the embryo “is the animal in its lessmodified state”
  6. 6. embryology: case forErnst Haeckel was a German embryologist and hepopularized Darwin’s 2 main ideas about embryology.He produced a set of influential drawings showing thatthe embryos of various classes of vertebrates were verysimilar during their earliest stages of development.
  7. 7. Haeckel’s Embryo’s
  8. 8. embryology: case forModern evolutionary biologists have modified Darwin’sand Haeckel’s ideas.They no longer think that embryos reveal the adult formof their evolutionary ancestors.Some scientists now think that embryos tell us whatthe embryos of their evolutionary ancestors might havelooked like.
  9. 9. embryology: case foronline resources
  10. 10. embryology: a reply Critics of the argument from embryology agree that common descent might be a reasonable idea, if the embryos really were similar in their earliest stages of development. But, according to most embryologists, they are not.
  11. 11. embryology: a reply Adam Sedgwich, of Cambridge University, in 1894, challenged Darwin’s claims. The embryo’s, of even closely allied animals, such as chickens and ducks, display specific differences very early in development. You can tell the difference between a duck and a chicken on the second day of development.
  12. 12. embryology: a reply If the early embryos are so different, then why did the erroneous claim become so popular? Critics states 2 reasons: 1. Haeckel’s drawings misrepresented the features of the embryos, he drew them incorrectly, in order to match Darwin’s theory. 2. Darwin and Haeckel both left out the earliest stage of development. This is critical because the embryos are quite different at this stage.
  13. 13. embryology: a reply Haeckel’s drawings became very widespread. They can be found in many biology textbooks today, with the claim that the vertebrate embryos are most similar in their earliest stages.
  14. 14. embryology: a reply In 1997, an international team of scientists, led by embryologist Michael Richardson, compared Haeckel’s drawings to photographs of actual embryos at various stages of development. They discovered that Haeckel distorted the evidence. Richardson told the journal Science, “it looks like it’s turning out to be one of the most famous fakes in biology.”
  15. 15. Richardson’s Picture Comparison
  16. 16. embryology: a reply Stephen Jay Gould wrote, “I think we 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 majority, of modern textbooks.”
  17. 17. embryology: a replyresources Evolution Exposed by Roger Patterson Speciation - page 57-67 Homology - page 68-72 Fossils (transitional) - page 73-74 Molecular Homology - page 74-75 Embryology - page 95-96 Refuting Evolution by Jonathan Sarfati The Politically Incorrect Guide to Darwinism and Intelligent Design by Jonathan Wells
  • MohamedFouad186

    Apr. 20, 2018


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