In a message dated 9/24/2000 3:21:21 PM Pacific Daylight Time,
sejones@iinet.net.au writes:
<<
Reflectorites
On Thu, 21 Sep 2000 11:07:04 EDT, Bertvan@aol.com wrote:
[...]
BV>The only answerable question I found in your post is "What is a
Darwinist".
>I define a Darwinist as those believing evolution can be explained by
>"chance variation and natural selection". Many of them want to add, "plus
>drift". I've never figured out what "drift" was other than more "chance
>variation", so it's ok with me.
SJ: Genetic drift is not so much "chance variation" but a way of bypassing
RM&NS altogether. >>
It's another mechanism through which variations can become fixated. Is it
anti-Darwinian? Does it prove Darwinian wrong? In my opinion it's an addition
to Darwinism just like punctuated equilibrium is claimed to be an addition.
And more additions will follow over time. Does this disprove Darwinism? Or
should we realize that the modern evolutionary theory has evolved from
Darwinism?
It is the fixing of genes in a small population by purely
<< I mentioned how in one of my labs we simulated RM&NS and then Genetic
Drift in reducing populations. It was quite amazing and counter-intuitive
how RM&NS was overridden by Drift as the population got smaller.
>>
Indeed, genetic drift can under certain circumstances counteract RM&NS.
<< The discovery of Genetic Drift effectively rendered Darwinism untestable,
and hence unscientific, as Patterson pointed out:
>>
Of course not. One can certainly not always eliminate genetic drift as the
mechanism but that does not mean that Darwinism becomes untestable or even
worse, unscientific. Notice that the "hence unscientific" is imho an
incorrect conclusion.
http://www.kheper.auz.com/gaia/biosphere/evolution/Darwinism.htm
<< "Darwinian evolution, by natural selection, predicts that organisms
are as they are because all their genes have been and are being
subjected to selection, those that reduce the organism's success
being eliminated, and those that enhance it being favoured. This is a
scientific theory, for these predictions can be tested. 'Non-
Darwinian' or random evolution predicts that some features of
organisms are non-adaptive, having neutral or slightly negative
survival value, and that the genes controlling such features are
fluctuating randomly in the population, or have been fixed because
at some time in the past the population went through a bottleneck,
when it was greatly reduced. When these two theories are
combined, as a general explanation of evolutionary change, that
general theory is no longer testable. >>
Patterson is clear here that this is the case only when the two effects are
combined.
Take natural selection: no
<< matter how many cases fail to yield to a natural selection analysis,
the theory is not threatened, for it can always be said that these
failures of selection theory are explained by genetic drift. >>
That would still show that NS was not responsible. Now the alternative is
genetic drift. Can genetic drift be eliminated as a mechanism? Potentially
yes.
And no
<< matter how many supposed examples of genetic drift are shown to
be due, after all, to natural selection, the neutral theory is not
threatened, for it never pretended to explain all evolution."
(Patterson C., "Evolution", 1978, p.70)
>>
I don't think that Patterson's comments support your assertion.
http://www.geocities.com/osarsif/ce09.htm
Also Patterson's comments seem to be a bit out-dated.
<< Of course just as undirected genetic changes like Genetic Drift can be
decisive in small populations, so could *directed* genetic changes
implemented by an Intelligent Designer in small populations!
>>
Sure, ID has not limits on what is possible. Of course it does require
supporting evidence. So far genetic drift has been observed. What about ID?
And certainly what about the ID SJ is proposing? I'd say none.
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