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Irreducible complexity

Discussion of everything related to the Theory of Evolution.

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Irreducible complexity

Postby shmband » Thu Jun 30, 2005 8:05 am

Hey all, I'm new here after being frustrated by lack of ability to get scientific answers from people elsewhere!

The problem of irreducibility is posed as an argument against Darwinism in such complex cellular features as Cylia, and indeed human cells in general. Can anyone get around this problem for me? Is there a current Darwinian argument as to how complex, multiple parted features like this might have come about?

Thanks!
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Postby clarence » Thu Jun 30, 2005 11:37 am

I have heard about irreducible complexity, from the book "Darwin's Black Box". It is a book authored by Michael Behe, a biochemist from Lehigh University. The complete title is "Darwin's Black Box: The Biochemical Challenge to Evolution", published in 1996 by Free Press. The book's thesis statement is that the "irreducible complexity" of biological systems at the molecular level holds evidence against biological evolution. Behe defines irreducible complexity as

"By irreducibly complex I mean a single system composed of several well-matched, interacting parts that contribute to the basic function, wherein the removal of any one of the parts causes the system to effectively cease functioning. An irreducibly complex system cannot be produced directly (that is, by continuously improving the initial function, which continues to work by the same mechanism) by slight, successive modifications of a precursor system, because any precursor to an irreducibly complex system that is missing a part is by definition nonfunctional. An irreducibly complex biological system, if there is such a thing, would be a powerful challenge to Darwinian evolution." (p. 39)

That topic is discussed more here: "Darwin's Black Box" http://www.biology-online.org/biology-forum/about8.html. I disagree with him; irreducible complexity can evolve. Possible mechanisms can be 1)parts being removed, 2)multiple parts being added (i.e. the whole system being duplicated), 3) functional change, 4)a part having a second function and 5)parts being gradually modified. All of these are being observed in genetic mutations. MMGW's post on the forum explains the above alternative mechanisms well.
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Postby shmband » Thu Jun 30, 2005 2:08 pm

It was after reading an interview with Behe that originally got me interested in the topic. I also noted an experiment cited by Kenneth Miller which allegedly showed evolution of irreducibly complex systems in action, but I've found a rebuttal which discredits Miller's claims.

I've also read some compelling refutes of the whole idea of parts of a I.C. system having other prior functions, because the chances of the coming together in the way they do are prohibitively small.

Thanks for that link, I'll go there and check it out. Cheers!
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Postby James » Fri Jul 01, 2005 10:39 pm

The arguement is fundamentally flawed, and I think this site gives credible, well versed reasons why:
http://www.simonyi.ox.ac.uk/dawkins/WorldOfDawkins-archive/Catalano/box/behe.shtml
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