Reflectorites
On Wed, 05 Apr 2000 11:33:57 -0500, Susan Brassfield wrote:
[...]
>BP>Sex is a bit of a problem for evolution. No one has been able to figure
>>out how a man and a woman could have evolved through functional
>>intermediates to develop a sperm/egg, and the male/female sex organs.
>>This is the classic example of Michael Behe's irreducible complexity.
SB>this is, of course, hogwash. Sex is not a problem at all for evolution.
>First, go to this note at the talk.origins website:
>http://www.talkorigins.org/origins/postmonth/may99.html
[...]
The wording above is illuminating: "this is, *of course*, hogwash" and
"Sex is not a problem *at all*..." (my emphasis). This is the `Freudian slip'
of a true believer to whom there can be no "problem at all for evolution",
even in principle, and therefore no scientific evidence is even necessary. All
one has to do is point to a `verse' in the evolutionist's `Bible', the
Talk.Origins website, and all will be well!
But someone better tell Maynard Smith, one of the world's leading
authorities on the origin of sex. In his book, "The Problems of Biology", he
included the origin of sexual reproduction among biology's "major
unsolved problems" (Maynard Smith J., "The Problems of Biology," 1986,
p.vii). 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)
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:
"Why Sex? We are so used to associating the ideas of sex and reproduction
that it is easy to forget that, at a deep level, these two processes are precise
opposites. Reproduction is the process in which one cell turns into two,
and sex that in which two cells fuse to form one. Darwin has taught us to
expect organisms to have properties that ensure successful survival and
reproduction. Why, then, should they bother with sex, which interrupts
reproduction? I have spent much of the past twenty years thinking about
this problem, which I regard as the most interesting in current evolutionary
biology. Yet this is the first time I have attempted to write about it for a
general audience. The reason is simple; I am not sure I know the answer. It
is always difficult to explain scientific ideas to non-specialists, but it is
doubly so if one is not clear about the ideas oneself So you may find this
essay confusing. However, if you are not a biologist you will probably learn
some curious and interesting facts. I must start by explaining why the
problem is so difficult. It is not merely that sex seems pointless: it is
actually costly." (Maynard Smith J., "Why Sex?" in "Did Darwin Get it
Right?," 1993, p165).
The sexual process of meiosis (in eukaryotes) and mitosis is fantastically
complicated halving the organism's DNA in a series of stages and then joining
it back together again (with crossover), with another organisms's DNA:
"meiosis, n. a type of nuclear division associated with sexual reproduction,
producing four HAPLOID(1) cells from a single DIPLOID(1) cell, the
process involving two cycles of division. Although meiosis is a continuous
process it has been divided into numerous stages, given below. Further
details of each stage can be obtained by referring to individual entries.
PROPHASE I: homologous chromosomes pair, split into CHROMATIDS,
and carry out CROSSING OVER. The nuclear membrane disintegrates.
METAPHASE I: chromosomes migrate to the spindle equator to which
they become attached by their CENTROMERES.
ANAPHASE I: HOMOLOGOUS CHROMOSOMES separate to opposite
poles.
TELOPHASE I: new nuclei form, in which there is only one type of each
chromosome, although each is divided into two chromatids.
PROPHASE II: nuclear membrane goes.
METAPHASE II: chromosomes attach to spindle.
ANAPHASE II: chromatids separate to poles.
TELOPHASE II: a total of four haploid nuclei is produced, each with one
of each types of chromosome.
Meiosis has two major functions: (a) it halves the number of chromosomes
to prevent a doubling in each generation, (b) it produces a mixing of
genetic material in the daughter cells by the process of INDEPENDENT
ASSORTMENT and RECOMBINATION. Note that the second point is
only true if variability already is present in the parent cell."
(Hale W.G., & Margham J.P., "Collins Reference Dictionary of Biology,"
1988, p.341)
"mitosis, n. a type of nuclear division by which two daughter cells are
produced from one parent cell, with no change in chromosome number.
Mitosis is associated with asexual growth and repair and, although it is a
continuous process, has been divided up into four main stages, given
below. Further details of each stage can be obtained by referring to
individual entries.
(a) PROPHASE: chromosomes contract and become visible as threads.
Each chromosome divides into two CHROMATIDS and the nuclear
membrane disintegrates.
(b) METAPHASE: chromosomes migrate to the equator of a spindle and
become attached to the spindle microtubes by their CENTROMERES.
(c) ANAPHASE: chromatids separate and go to opposite poles.
(d) TELOPHASE: nuclear membrane reforms, chromosomes lengthen and
cannot be distinguished."
(Hale W.G., & Margham J.P., "Collins Reference Dictionary of Biology,"
1988, p.341)
Of course, since Maynard Smith is a very clever person and has all the vast
resources of modern science at his disposal, he does manage to suggest
some `just-so' stories which might explain why sex originated.
But they only explain the long-term advantages of sex *after* it has arisen.
The real problem for Darwinism is that each small step in the process has to
have a selective advantage, otherwise natural selection (if it is to have the
power ascribed to it), would eliminate it. A `blind watchmaker' cannot see
and head for a long-term advantage, but an Intelligent Designer can. Thus
Maynard Smith writes:
"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).
And:
"The origin of the sexual process remains one of the most difficult
problems in biology. I cannot attempt to answer it here, but l can explain
the difficulty The major consequence of sex was to make genetic
recombination possible, once the 'old-fashioned' prokaryote methods of
plasmid transfer and conjugation had become ineffective. Genetic
recombination, in turn, enormously expands the possibilities of evolutional
change, as was illustrated in Figure 6. But this is a long-term, prospective
advantage, not an immediate one. 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).
He concludes his "The Problems of Biology" with:
"The hardest questions are those concerned with the evolutionary causes,
and consequences, of this pervasive genetic recombination. The questions
are hard because a recombinational event may have no effect on the fitness
of the individual in which it occurs, but only on what other genes a
particular gene will associate with in future generations. The hardest
question of all concerns the evolution of sex in eukaryotes, because of the
twofold advantage to females that abandon it." (Maynard Smith, 1986,
p.38)
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!
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!
Kerkut considers this complacent attitude a real problem for science:
"For some years now I have tutored undergraduates on various aspects of
Biology. It is quite common during the course of conversation to ask the
student if he knows the evidence for Evolution. This usually evokes a
faintly superior smile at the simplicity of the question, since it is an old war-
horse set in countless examinations. "Well, sir, there is the evidence from
palaeontology, comparative anatomy, embryology, systematics and
geographical distributions," the student will say in a nursery-rhyme jargon,
sometimes even ticking off the words on his fingers. He would then sit and
look fairly complacent and wait for a more difficult question to follow,
such as the nature of the evidence for Natural Selection. Instead I would
continue on with Evolution.
"Do you think that the Evolutionary Theory is the best explanation yet
advanced to explain animal interrelationships?" I would ask.
"Why, of course, sir," would be the reply in some amazement at my
question." There is nothing else, except for the religious explanation held
by some Fundamentalist Christians, and I gather, sir, that these views are
no longer held by the more up-to-date Churchmen."
"So," I would continue, "you believe in Evolution because there is no other
theory?"
"Oh, no, sir," would be the reply, "I believe in it because of the evidence I
just mentioned."
"Have you read any book on the evidence for Evolution?" I would ask.
"Yes, sir," and here he would mention the names of authors of a popular
school textbook, "and of course, sir, there is that book by Darwin, The
Origin of Species."
"Have you read this book?" I asked.
"Well, not all through, sir."
"About how much?"
"The first part, sir."
"The first fifty pages?"
"Yes, sir, about that much; maybe a bit less."
"I see, and that has given you your firm understanding of Evolution?"
"Yes, sir."
"Well, now, if you really understand an argument you will be able to
indicate to me not only the points in favour of the argument but also the
most telling points against it."
"I suppose so, sir."
"Good. Please tell me, then, some of the evidence against the theory of
Evolution."
"Against what, sir?"
"The theory of Evolution."
"But there isn't any, sir."
Here the conversation would take on a more strained atmosphere. The
student would look at me as if I was playing a very unfair game. It
would be clearly quite against the rules to ask for evidence against a
theory when he had learnt up everything in favour of the theory. He
also would take it rather badly when I suggest that he is not being very
scientific in his outlook if he swallows the latest scientific dogma and,
when questioned, just repeats parrot fashion the views of the current
Archbishop of Evolution. In fact he would be behaving like certain of
those religious students he affects to despise. He would be taking on
faith what he could not intellectually understand and when questioned
would appeal to authority, the authority of a "good book" which in this
case was The Origin of Species.
(Kerkut G.A., "Implications of Evolution," , 1960, pp.3-5)
Steve
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"Neither, secondly, would it invalidate our conclusion, that the watch
sometimes went wrong, or that it seldom went exactly right. The purpose
of the machinery, the design, and the designer, might be evident, and in
the case supposed would be evident, in whatever way we accounted for the
irregularity of the movement, or whether we could account for it or not. It
is not necessary that a machine be perfect, in order to shew with what
design it was made: still less necessary, where the only question is, whether
it were made with any design at all." (Paley W., "Natural Theology: or,
Evidences of the Existence and Attributes of the Deity, Collected from the
Appearances of Nature," [1802], St. Thomas Press: Houston, TX, 1972,
reprint, pp.3-4)
Stephen E. Jones | sejones@iinet.net.au | http://www.iinet.net.au/~sejones
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