From: colby@bu-bio.bu.edu (Chris Colby)
Newsgroups: talk.origins
Subject: some more stuff about fruit flies
Date: 11 Oct 92 04:30:17 GMT
Organization: animal -- coelomate -- deuterostome

In article <7228@tekig7.PEN.TEK.COM> alanf@tekig6.PEN.TEK.COM (Alan M Feuerbacher) writes:

>>>  But when Morgan carried the
>>>  experiment further, inbreeding this new eyeless strain, he found that
>>>  within a short time, perfectly formed eyes appeared! 

>>Does the book give an actual ref, what experiment exactly did
>>[he] perform?

>Then Fix talks about Richard B. Goldschmidt's observation [possibly in
>_The Material Basis of Evolution_, 1940] that mutations in fruit flies
>    were all so incredibly micro that even if a thousand were combined
>    in one specimen, it would still not amount to a new species.

Goldschmidt was a proponent of saltationary evolution -- evolution
via the hopeful monster. The primary data for his theory was that
characters that varied within species of [whatever clade of organisms
he studied, moths I think, but don't quote me] were different from
the characters that varied among species. Fix is ignoring the fact
that evolution works by cummulative selection, not mass mutation.
He therefore has latched onto a legitimate scientist's argument and
distorted it to serve his own purpose. What he neglects to mention
is that Goldschmidt's theory is not well accepted, and that his
statement regarding fruit flies is simply ignoring how scientists
propose evolution works.

>Next Fix writes about DNA and a number of anomolies related to it,
>p. 188-190:

>    Indeed, in a larger perspective, the close resemblance of human
>    and chimp DNA really represents another evolutionary problem,
>    rather than a solution.  Comparisons of DNA in frogs show that
>    there is much greater DNA variation among them than there is
>    between the bat and the blue whale;

This is true.

>    If we are drawing conclusions about man's evolution using DNA
>    comparisons, we then have to do a lot of explaining about those
>    variations found in nearly identical frogs.

Here Fix is just plain confused, DNA sequences are used to construct
phylogenies. They are not used to in "drawing conclusions about
man's evolution", at least not conclusions other than his relations
to other primates. Variation within and among species does not need
to be mirrored exactly in morphology. There is plenty of "junk" DNA
in the genome that is free to vary without inducing phenotypic
changes in the organism. Likewise, small changes in regulatory genes
can cause large changes in phenotype. If Fix is saying that one
cannot look at DNA sequences and tell how a suite of characters
evolved, he is right. But, nobody is claiming that you can -- its
just used in drawing phylogenies.

>    These anomalous results are but one indication that the so-called
>    `point mutations' do not themselves produce changes in form.

BZZT, point mutations can have large phenotypic effects. Fix is
just ignoring reality here.

>    There seems to be something else controlling the organism.
>    Microbiologists believe this is the `regulator genes' -- a subject
>    that occasions amusement among some paleontologists and geologists
>    of the stone-throwing variety, since the biologists must ascribe
>    so much to these regulators without having identified a single
>    one, despite very long and diligent search. 

Fix should have opened a genetics text and read about homeotic genes.

>    The author of virtually every
>    contemporary book supporting evolution trots out the human-chimp
>    DNA comparison, but very few mention the frogs or another
>    discovery of microbiology that has been known for some time.

I've heard the frog story numerous times, what about it does Fix
think contradicts evolution? The frogs simply have accumulated a lot of
neutral variation while staying morphologically similar -- humans and
chimps, on the other hand, have diverged phenotypically but have done
so without accrueing much variation. If Fix understood the concepts
of neutral variation, stabilizing selection and directional selection
he might not have embarrassed himself by writing such idiocy.

>	[Speaking about homology]. Now if these various
>	structures were transmitted by the same gene-complex, varied
>	from time to time by mutations and acted upon by environmental
>	selection, the theory would make good sense.  Unfortunately
>	this is not the case.  Homologous organs are now known to be
>	produced by totally different gene complexes in the different
>	species. 

Bullshit, where's Fix's evidence for this? If this were true, it
would indeed be a big problem for evolution. 

[his reference for this claim]
>	[Randall, John L., _Parapsychology and the Nature of Life_,
>	New York: Harper & Row, 1975]

A parapsychology text? Gee, I don't know if that constitutes
evidence. I'll wait and see what my psychic astrologer says first.
Has the National Enquirer come out with an opinion on this?

>    If the results of these experiments is true, it seems to me to
>    imply that at least some of the DNA has some sort of
>    error-correction function, true or false?

How about going to the library, picking up a genetics(*) text and
finding out for yourself? There are certainly mechanisms that
correct base pair changes during replication and in response to
mutagens, but that doesn't seem to be the question you are asking.

(*)Try Watson, et.al., 1987, Molecular Biology of the Gene, Benjamin/
Cummings, Manlo Park, California. See especially chapter 12 "The
mutability and repair of DNA" and chapter 22 "The molecular
biology of development" (homeotic genes are discussed here).

Fix clearly knows nothing about the subject he is writing about.
This sort of creationist argument isn't even interesting. Simply
asserting things contrary to reality is hardly a compelling line
of argumentation. Fix needs to pull his head out of his ass and
stick it in a genetics book. 

>Alan Feuerbacher

Chris Colby 	---	 email: colby@bu-bio.bu.edu	---
"'My boy,' he said, 'you are descended from a long line of determined,
resourceful, microscopic tadpoles--champions every one.'"
 	--Kurt Vonnegut from "Galapagos"