Thursday, April 19, 2012

Vesigial Organs Recap

I thought it would be a good to critique and reflect upon some of the earlier posts and commentary I have made throughout the semester about vestigial organs.

There is mounting evidence and proposed theories out there advocating different explanations for how certain vestiges have evolved and what their function actually is. However, one important question to consider is how pertinent are these arguments to the broader picture of assessing evolutionary changes?

I have compiled some key recaps of statements made by experts to capture the view of incompleteness of the vestigial organ argument. 
  1. It is not possible to actually prove the uselessness of a given organ.Evolutionary zoologist S. R. Scadding:
    The ‘vestigial organ’ argument uses as a premise the assertion that the organ in question has no function. There is no way this negative assertion can be arrived at scientifically. That is, one can not prove that something does not exist (in this case a certain function), since of course if it does not exist one cannot observe it, and therefore one can say nothing about it scientifically.  Since it is not possible to unambiguously identify useless structures, and since the structure of the argument used is not scientifically valid, I conclude that ‘vestigial organs’ provide no special evidence for the theory of evolution.
  2. Some organs, although apparently functionless, are not derived from evolutionary ancestors in which the structures originally had a function. 
In analysis and reflection of Darwin's idea of the mammalian genitalia: These structures . . . clearly reflect the embryonic development of a sexually dimorphic organism which begins its development in a sexually indifferent condition with structures characteristic of both sexes. They do not reflect phylogenetic development. No one supposes males evolved from females or vice versa.
  1. Organs exhibiting reduced function or no function provide poor evidence for a process supposed to generate organs with new functions
    The existence of degenerate structures does not show that microbe-to-man evolution has taken place.

    Considered sources:
    Bergman, Jerry, and George Howe. 1990. “Vestigial Organs” Are Fully Functional. Terre Haute, IN: Creation Research Society Books.

    Darwin, Charles. 1958. Origin of Species. (reprint of 6th edition). New York: Mentor.

    Scadding, S. R. 1981 (May). Do ‘Vestigial Organs’ Provide Evidence for Evolution? Evolutionary Theory, Vol. 5, pp. 173-176. 
     
     

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