Re: the role of sex in evolution

From: Cliff Lundberg (cliff@cab.com)
Date: Fri Apr 07 2000 - 02:08:01 EDT

  • Next message: Susan Brassfield: "Re: the role of sex in evolution"

    Stephen E. Jones wrote:

    >But someone better tell Maynard Smith, one of the world's leading
    >authorities on the origin of sex.

    If the point is that the origin of sex is not presently known, what is
    the point of the citation? How can one be a leading authority on
    something that is not known?

    If reproduction is to allow the continuance of a population,
    rather than simply being a clonal continuance of individuals,
    there must be a way for individuals to share genetic information.

    Simple organisms need only merge. Metazoans need mechanisms
    to support this process. Darwin's suggestion that the primitive state
    among these was hermaphrodity seems reasonable; separate sexes
    is a further development, a complication.

    I suspect that those asking 'why sex?' really want to know why there
    are two distinct sexes. We can only surmise that this is an efficiency
    that was selected for, to let males compete, to specialize in testing
    genetic combinations, while females specialize in the drudge work
    of reproduction.

    >He explains the basic problem is that:
    >"...it is reproduction, not sex, which is a precondition for evolution" and at
    >the most fundamental level sex and reproduction are exact opposites. In
    >reproduction, one cell turns into two, whereas the essential feature of the
    >sexual process is that two cells fuse to form one. Thus sex is an
    >interruption of reproduction. Since, other things being equal, natural
    >selection favours those types which reproduce most rapidly, there are real
    >difficulties in giving a selective explanation for the widespread occurrence
    >of sexual fusion. These difficulties are still unresolved, although many
    >solutions have been suggested." (Maynard Smith, 1986, p.27)

    Amazing that an evolutionist would find it difficult to accept that the value
    of genetic recombination for a species should override the disadvantage
    that a pair of cells briefly becomes one cell just before exponential cellular
    multiplication occurs.

    >Yet, even though Maynard Smith is one of the world's leading authorities
    >on the origin of sex, and has been thinking about it for 20 years, even he
    >says that he doesn't know the answer:

    Well, if he's thought about it 20 years without deducing the mechanisms
    of its origin, it must be a product of ID? Is this the logic here? What if
    someone thought about ID for 20 years without finding proof of ID?

    >"There is, however, a second objection that is harder to meet. Are we not
    >again ascribing foresight to evolution? We are saying that a species will not
    >abandon sex today, because the environment may change tomorrow."
    >(Maynard Smith J., 1993, p.168).

    Species do abandon sex, at the cost of the power to adapt.

    >Natural selection lacks foresight. A trait
    >will not be selected merely because it will have, at some time in the future,
    >beneficial effects. It is only present benefits that count." (Maynard Smith,
    >1986, p.35).

    A non-beneficial trait may arise and endure simply by being linked
    with beneficial traits. In any case, it's very odd to speak of something
    as general as sexual reproduction as 'a trait'.

    >Maynard Smith's attempted explanations are ingenious (especially in his
    >"The Major Transitions in Evolution" 1995), but they would only be
    >convincing to an already convinced evolutionist who knows that `evolution
    >is a fact' and so does not actually *need* any evidence!

    Given the enumeration of the details of meiosis, I guess what we're getting
    is just the argument from personal incredulity. But where is the positive
    argument for ID? Why is this bizarre process an intelligent solution to
    a design problem?

    >Therefore, of *course* "Sex is not a problem at all for evolution" to Susan.
    >*Nothing* could ever be "a problem at all for evolution" to a true believer
    >in evolution!

    In science, it's not a problem that there are problems. Science is concerned
    with questions, not answers.

    --Cliff Lundberg  ~  San Francisco  ~  cliff@cab.com



    This archive was generated by hypermail 2b29 : Fri Apr 07 2000 - 03:52:32 EDT