Re: Evolution Statement

Date: Sat Dec 08 2001 - 06:14:13 EST

  • Next message: george murphy: "Re: Evolution Statement"

    In a message dated 12/6/01 2:26:01 PM, writes:

    << Can we improve on this? >>

    Here are my comments on the "opening statement" to the website that Dick
    brought to our attention.

    I take it the following is the definition of evolution employed in this
    statement: <<Biologists accept as fact that all organisms, living and
    extinct, have descended, with innumerable changes, from one or at most a few
    original forms of life.>> In short, "descent with modification" (DWM) is the
    definition of evolution used in this statement. Do we agree on that?

    I accept the (DWM) as a partial definition of evolution, but with a minor
    proviso that this definition holds best within recent species and is more
    problematic the farther one goes back in the history of organic life. The
    statement fails to mention that, and would be improved if it did.

    The statement fails to address the critical question: What is the mechanism
    that brought about DWM? That brings us to the heart of the matter, because
    the answer must be, natural selection. Nicht wahr? (True, genetic drift and
    neutral mutations possibly direct genetic exchange in very early organisms
    are sometimes invoked as change agents, but they are relatively minor causal
    factors.) If natural selection is not the major change agent in the overall
    course of DWM, please correct me and tell me what is.

    What amazes me, however, is that the words "natural selection" do not even
    appear in the statement. How can one make an introduction to evolution and
    not mention the most famous and controversial words in the evolutionists'
    lexicon? So, IMHO, the statement would be improved if it stated forthrightly
    that natural selection is considered to be the major mechanism that drove DWM.

    But to do so would introduce a problem that the statement probably wanted to
    avoid, namely, that the only direct evidence we have that natural selection
    is the causal factor in DMW is bacterial resistance to antibiotics, and what
    Gould called "short-term evolution" (STE) studies, such as the finch's beak,
    peppered moths, spotted guppies, and so forth. These studies are the only
    basis for the claim that natural selection is the causal factor for all
    changes we see in the fossil record and the tree of life. The operation of
    natural selection throughout the entire tree of life is an extrapolation from
    such studies. Or to say it differently, evolutionary biologists hold that
    socalled macroevolution, or large innovative changes in DWM is
    microevolution WRIT LARGE. This claim, however, is not a fact. Thus while
    DWM itself is factual, its mechanism is not.

    To continue, such an extrapolation is unwarranted because of the simple fact
    that changes observed in STE studies and bacterial resistance are
    _reversible_. While finch's beaks become more robust in times of drought
    when seeds have tougher shells, they revert to the more slender shape when
    climate returns to normal and seed shells less hard to crack. Such
    reversibility disqualifies STE from serving as the mechanism of DWM, or at
    least raises serious questions about it. The statement would be more
    forthright and therefore improved if it acknowledged this.

    Finally, DWM has produced the enormous diversity of life forms in the tree of
    life. This is acknowledged briefly in the statement. Natural selection is
    ideally suited to produce diversity. But what is more difficult to explain
    is _disparity_, or the highly organized nature of the organic world, with its
    deep discontinuities between the major families of organism, roughly
    designated as phyla, using natural selection as the operating change agent.
    Dobzhansky stated, "fundamental characteristics of organic diversity-- [are]
    its discontinuity and hierarchical organization." If such a giant as
    Dobzhansky made such a statement, shouldn't the statement under consideration
     at least acknowledge that existence of the hierarchical organization and
    discontinuities in nature, instead of silently passing by on the other side
    of the road?

    IMHO, the statement is made to be as non-controversial as possible. In doing
    so it omitted important concepts, which, I for one consider to be essential
    in an adequate discussion of Darwinian evolution.


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