Re: what comes next-the chicken or the fox?

From: David Campbell (bivalve@mailserv0.isis.unc.edu)
Date: Mon Jan 17 2000 - 10:33:50 EST

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    >Here is that great elastic word again, evolved. And, it seems to mean
    >almost anthing depending on the agenda of the user. What I want to see
    >is invention of a new organ. To make it clear, how about a sonar for the
    >fruit fly. Not small changes but something that clearly passes the
    >proported irreducible complexity barrier. We stipulate small changes
    >and changes in gene frequencies and improved hardiness and longer legs.
    >Has there been a fruit fly that developed a sonar in these laboratory
    >tests?

    Evolution simply means change over time, so it does apply to all sorts of
    things.

    No fruit flies with sonar are known to me, but there are moths with sonar
    jamming as a defense against bats. Extra legs, wings, and eyes have been
    generated in fruit flies in the lab. Normal fruit flies can see, so sonar
    is not very useful. They eat old fruit, which is better located by smell
    than by sonar, even in the dark.

    The evolution of a novel hearing organ in other flies has been traced.
    Although it is a unique, complex structure, study of related species shows
    the steps involved in its formation.

    There are some physical traces of the evolution of sonar in the skull
    structure of early whales.

    >Futher, anytime an inbreed profession is challenged from the outside,
    >instead of responding to the issue, all that is necessary is that they
    >brand the intruder with a comment such as "Sagan is not a biologist."

    That was intended as a conclusion, not as a piece of evidence. Based on
    your description of his claims, Sagan did not know what he was talking
    about with regard to fruit flies, although it could partly be merely
    outdated. The range of mutations created includes flies with more than six
    legs, contrary to the standard for the entire class of insects, as well as
    flies with four wings, contrary to the standard for the entire order of
    flies. If some of these mutants were to be successful in nature, we might
    have trouble figuring out what they were. However, work on fruit flies is
    mostly genetics. To the limited extent that geneticists have tried to
    induce fruit flies to evolve, they have. Mostly, geneticists are trying to
    find out what genes do rather than induce anything resembling large-scale
    natural evolution. They are not trying to test "macroevolution" and may
    not know much about it.

    Some experiments on bacteria have come closer to simulating evolution by
    natural selection. I do not know if all the resulting changes have been
    characterized genetically.

    David C.



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