Wednesday, April 7, 2010
Embryology
In Chapter 3, "Remnants: Vestiges, Embryos, and Bad Design," Jerry Coyne illustrates how all vertebrates begin development in the same way, looking rather like an embryonic fish. As development proceeds, different species begin to diverge - but in weird ways. Some blood vessels, nerves, and organs that were present in the embryos of all species at the start suddenly disappear, while others go through strange contortions and migrations. Eventually, the dance of development culminates in the very different adult forms of fish, reptiles, birds, amphibians and mammals (73). The embryo replays evolutionary history from our origins from fish to our current evolutionary stage mammal but only the embryonic remnant's of past organisms appear during the embryonic stage. What do you believe causes the embryo to cease development after achieving the embryonic form of each ancestor during embryonic stage?
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I believe that the key to the cease development once attaining embryonic form is what all living organisms have: DNA. DNA contains different types of coding patterns that scientists have noted. Of these, there are special lines of code that are similar to that of yeast, fish, and other organisms that we normally do not associate with humans. This code is known as ancient code. This code is common to all organisms, so I believe that if even such code exists, there must be code that is remnants of a certain ancestral organism. source: http://www.pbs.org/wgbh/nova/genome/explore_wave.html#
ReplyDeleteYes, I agree with Andrew here. Organisms' phenotypes, physical traits, are determined by gene expression. Expressing certain genes will code for the translation of certain mRNA, resulting in transcription of certain proteins, resulting in different organisms (http://genome.wellcome.ac.uk/doc_WTD020757.html). The differing developmental processes of embryos are results of different gene expression.
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