Re: [asa] chromasome fusion #2

Surely the whole point about it being potentially a problem for the
theory of evolution is this;

Suppose we had NOT found evidence of the fusion of two chimp
chromosomes & our chromosome 2 was nothing like any of the ape
chromosomes (or suppose the extra chromosome pair was just missing).
Both these instances show a massive change to the genome that occurred
somewhere along the line, which is not consistent with a gradualistic
process. However, a fusion of two is a single event, consistent with
gradualism. So the finding or not finding of the fusion evidence is
potentially a falsifier of a gradualist theory of evolution.

Iain

On Mon, Jul 13, 2009 at 2:55 AM, wjp<wjp@swcp.com> wrote:
> Apparently chimpanzees, and other primates, have 48 chromosomes
> while humans only have 46.
>
> From an evolutionary standpoint this is suppose to be a problem.
> Why is that?
>
> It is presumed that chimps and humans have a common ancestor.
> So I suppose the reasoning is that if one ancestor of the
> common ancestor has 48 chromosomes and another has 46 there
> is a problem in believing they had the same ancestor.
>
> The reasoning might be that since chromosome number is
> directly related to inherited traits that it might be
> difficult to see how an ancestor with 48 chromosomes could
> produce (in no matter the number of steps) an offspring
> with only 46.
>
> Now I, being naive, don't see why this is suppose to be so
> great, or insurmountable a problem.
> After all, if evoultion is correct, something like this must
> be commonplace.  Presumably the earliest of creatures had fewer
> chromosomes than later species.  So somehow chromosomes must be
> added and I'm not certain why it should any more mysterious how
> chromosomes can be added than that they can be taken away.
>
> In any case, Ken Miller asserts that this is so great a problem that
> unless it were resolved evolution must be wrong.
> I am astonished by this statement and can hardly believe that he really
> means it.  In fact, it seems far more obvious that the reason he
> says this is because he believed at the time of the statement that a
> resolution was already at hand.
>
> In any case, the resolution supposedly is that the second chromosome fused
> with another chromosome, and since chromosomes come half from each parent,
> this would result in 46 chromosomes instead of 48.
>
> All I want to say about the supposed evidence that a chromosome had fused
> is that it does not entail that evolution occurred, rather it is merely
> consistent with an evolutionary development.
>
> The story, I suppose, would be something like that the ancestor of both
> man and chimp has 48 chromosomes, but somehow one chromosome in man
> became fused to another, while that of the chimp and other primates did
> not.
>
> The notion of fused chromosomes is not necessarily associated with an
> evolutionary process, unless one means by evolution that something
> that existed previously was used in the creation of something new.
> Such a view of evolution could as well be the work of an intelligent
> designer, which is why I am confused by Ken Miller's apparent
> confidence that evolution is clearly a superior explanation.
>
> The very notion of fusion appears to entail a process whereby something
> changed from not being fused to being fused.  The notion appears to
> entail that there was a time when they were not fused and somehow became
> fused.  It is true that if we presume that such processes must take place,
> then fusion would be consistent with that presumption.  But does the
> evidence for fusion really entail that a fusion has taken place?
> In order for fusion to have taken place we must have a time when
> they were not fused.  But the mere fact that they appear to be fused
> does not entail that they were ever not fused.
>
> It seems then that here, as in all of science, we proceed abductively,
> from theory to evidence and then back again to theory.
> But in all cases the science finds a theory that is consistent with the
> evidence.  There is no way to argue from the evidence to a unique
> theory.  The supposed discovery of the fusion of chromosome #2 is
> consistent with an evolutionary story, but it could just as well be
> consistent with other theories and explanations.  This is, of course,
> true of all our knowledge of the physical world.
>
> What is surprising to me is that some think that this discovery is
> of great importance.  Yet it seems to me that the result is more
> or less assured by the supposed discovery that chimp DNA and
> human DNA are so very similar.
>
> I do not understand, I confess, why chromosomes are so important.
> It seems to me that they are mostly an artifact from an earlier
> state of biological science.  Hence, I don't understand why fusion would
> seem so important.  But, then again, I probably don't understand why
> the bunching of DNA that can be observed under a microscope should be so
> important.
>
> bill
>
>
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