Re: [asa] Randomness in evolution (was Review of Behe in Books and Culture)

Wanted to pose a question relating to the quote Pim
cited:
"> <quote>On the basis of much evidence, scientists
> have concluded that
> mutations occur randomly. The term "random" here has
> a specific
> meaning that is often misunderstood, even by
> biologists. What we mean
> is that mutations occur irrespective of whether they
> would be useful
> to the organism. Mutations are simply errors in DNA
> replication. Most
> of them are harmful or neutral, but a few of them
> can turn out to be
> useful. And there is no known biological mechanism
> for jacking up the
> probability that a mutation will meet the current
> adaptive needs of
> the organism. Bears adapting to snowy terrain will
> not enjoy a higher
> probability of getting mutations producing lighter
> coats than will
> bears inhabiting non-snowy terrain.</quote>

A couple of months ago, a (non-scientist) friend of
mine mentioned the following lizard experiment (see:
http://www.dinosauria.com/jdp/evol/lizard.html for a
quick summary, though I suspect you're already
familiar with it) in which a study intended to
understand extinction ended up producing rapid
evolution on the macro-scale.

Now, if evolution is really "random" in the sense that
there is "no known biological mechanism for jacking up
the probability that a mutation will meet the current
adaptive needs of the organism.", how is it that these
lizards were able to mutate in exactly the needed way
in a relatively short amount of time? (even given that
they probably have faster reproduction rates) I can
think of at least two hypotheses: 1) the new
environment increased the stress levels of the
lizards, influencing the chemical and hormone levels
in such a way as they triggered an increase in the
frequency of mutations (i.e. the difference between
scribbling a note quickly versus carefully crafting a
letter), therefore increasing the likelihood of
mutations and/or 2) the lizards already had the DNA
for the adaptations they needed, but it was dormant
until triggered.

Have these possibilities been studied, and if so, are
they supported? Even if true, (particularly in the
case of hypothesis #1), would it be an adequate
mechanism to produce the observed evolutionary effects
in such a quick time period?

As for my friend, he concluded that this was God's
work, not evolution's per se--wonder if he's right?

Christine (ASA member)

--- PvM <pvm.pandas@gmail.com> wrote:

> The problem is that Behe insists that most anything
> has been designed
> in evolution, even though he accepts common descent.
> His argument is
> that most if any complexity cannot be explained by
> evolutionary
> theory, although he fails to present any relevant
> explanation himself.
> The problem is that his argument is built on a shaky
> foundation
> (malaria) and contradicted by much what we do know.
> In addition,
> circular reasoning leads to tempting though
> fallacious conclusions.
> But yes, Behe had to accept the facts of common
> descent although he
> still rejects 'random mutations' and selection as
> able to explain much
> of any complexity.
>
> See
>
http://scienceblogs.com/goodmath/2007/05/behes_dreadful_new_book_a_revi_1.php
> or
>
http://www.pandasthumb.org/archives/book_reviews/the_edge_of_evo/
> or
>
http://endogenousretrovirus.blogspot.com/2007/05/good-virus-bad-creationist.html
>
> and the excellent review of Behe's arguments on
> cilia et al by Nick Matzke
>
http://www.pandasthumb.org/archives/2007/06/of_cilia_and_si.html
>
> Jerry Coyne:
>
http://richarddawkins.net/article,1271,The-Great-Mutator,Jerry-Coyne-The-New-Republic
>
> <quote>On the basis of much evidence, scientists
> have concluded that
> mutations occur randomly. The term "random" here has
> a specific
> meaning that is often misunderstood, even by
> biologists. What we mean
> is that mutations occur irrespective of whether they
> would be useful
> to the organism. Mutations are simply errors in DNA
> replication. Most
> of them are harmful or neutral, but a few of them
> can turn out to be
> useful. And there is no known biological mechanism
> for jacking up the
> probability that a mutation will meet the current
> adaptive needs of
> the organism. Bears adapting to snowy terrain will
> not enjoy a higher
> probability of getting mutations producing lighter
> coats than will
> bears inhabiting non-snowy terrain.</quote>
>
> Seems that Behe may object, based on flawed
> reasoning, to the use of
> the term 'random'.
>
> Dawkins
>
>
http://www.nytimes.com/2007/07/01/books/review/Dawkins-t.html?ex=1184126400&en=e79f10ed91676279&ei=5070
>
>
>
> Behe's musings lead him to conclude that for
> instance malaria has been
> 'designed', interesting admission though...
>
>
>
> On 7/9/07, David Opderbeck <dopderbeck@gmail.com>
> wrote:
> > Interesting review of Behe's new book in Books &
> Culture:
> >
>
http://www.christianitytoday.com/bc/2007/004/9.38.html
> >
> > Personally I haven't yet read Behe's latest,
> though I've read a few of the
> > blog / review slavos for and against. It's
> interesting to me, though, that
> > there has been such a violent reaction when Behe
> apparently concedes so
> > much. The B&C reviewer, for example, notes the
> following:
> >
> >
> > Behe disagrees [with most creationists when he
> says]: "Evolution from a
> > common ancestor, via changes in the DNA, is very
> well supported." After
> > summing up the argument from the genetic
> similarity of all life, Behe writes
> > that "It's hard to imagine how there could be
> stronger evidence for common
> > ancestry of chimps and humans." And again, "Let's
> acknowledge that genetics
> > has yielded yet more terrific (and totally
> unanticipated) evidence of common
> > descent." Finally (though many more examples could
> be cited), "The
> > purposeful design of life is also fully compatible
> with the idea of
> > universal common descent, one important facet of
> Darwin's theory" [emphasis
> > added]. Behe is quite clear that he has no
> objection to the idea that
> > species as distinct as mice and whales evolved
> from common ancestors.
> >
> > I gather, then, that Behe is making a
> meta-argument about the role of
> > "chance" in evolution. How different is Behe's
> position on this than, say,
> > that of Simon Conway Morris, or even in some
> respects that of Francis
> > Collins? It sees that Behe is further away from
> the Uncommon Descent crowd
> > than he is from Francis Collins.
>
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Received on Mon Jul 9 22:18:35 2007