RE: Peppered Moths - in black and white (part 2 of 2)

Donald Frack (
Tue, 30 Mar 1999 13:36:14 -0800


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> Donald Frack quoted Michael Majerus:

>> The case of melanism in the peppered moth IS ONE OF THE BEST EXAMPLES
>> that we have. In general it is based on good science and it is sound.

> What about the distinction between variation and evolution? Pierre Grasse
> is the only one I recall who explicitly raises this issue.

Kevin O'Brien has already commented on the conflation between "variation"
used as a noun and a verb here. If you are as familiar with the literature
as your comment implies, then I'm sure you know that Grasse has his own
personal views on evolution, not shared by most scientists, and is
explicitly anti-Darwinian. For nearly a century and a half, variation has
been considered part of the study of evolution. If you wish to join Grasse,
be my guest. Creationist author Philip Johnson uses Grasse as a weapon
against "Darwinism", but recognizes that Grasse has resorted to vitalism in
evolution as an alternative. Regarding the future discovery of "the exact
mechanism of evolution", Grasse concludes his 1973 book (English translation
1977) with "Perhaps in this area biology can go no farther: the rest is

> Species have ranges of variation, and the environment can, by natural
> selection, favor a preponderance of a particular variation. When does
> variation become evolution? I would think the answer is 'when the
> variation is irreversible.' By this standard, the peppered moth phenomenon
> is not evolution.

Well, if you get to define terms to your personal satisfaction, then I guess
you can define the outcome to suit yourself too. Personally, "when the
variation is irreversible" does not compute. The only sense I can make out
of it is that you are talking about speciation. If so, you leave the events
that lead up to speciation in a separate, and apparently unimportant,
category. Nearly all biologists would disagree with your separation, and
its unimportance.

If you get to define evolution to exclude the study of "variation"
(population changes?), then demark evolution to exclude variation that is
"reversible", then, sure, the peppered moth data do not show evolution.
Under these restrictions, no one except creationists has said they do.

Don Frack