Re: Robert Matthews on the Peppered Moth

Kevin O'Brien (
Mon, 22 Mar 1999 17:27:09 -0700

KLOB: This issue is a dead horse in the scientific community, but as Robert
Matthews -- author of the piece -- predicted, creationists are continuing to
whip it in the hope of getting some more mileage out of it before it
collapses completely. Yet the poor beast has run its course and should be
allowed to rest in peace, like any dead issue.

DJT: First - it should NOT be a dead horse, as there are some very
important lessons that should be learned from the whole issue.

For once I agree. For example, this issue teaches us that scientists can
make mistakes, but that evolutionary science, like any other science,
corrects itself when the evidence shows that it is wrong. But then
scientists already knew that, which is why it is a dead issue.

In contrast, I have never heard any creationist -- even those on this
list -- admit to any but the slightest of errors in their personal
speculations, and my examination of creation science as a whole indicates
that it essentially never corrects itself, even when other creationists
point out the errors.

What kind of lessons did you have in mind?

DJT: Second, the Peppered Moth story is STILL being put before the public
by at least one prominent evolutionary scientist. It obviously is NOT a
dead horse for him!

More appeal to authority: this must be a real issue, because Dr. Benton
Quest -- a prominent evolutionary scientist -- promotes it. Unless, of
course, Dr. Benton Quest doesn't realize that the issue has been refuted, or
refuses to accept the refutation because he is promoting a religious or
political agenda that has nothing to do with science. Or he is an idiot.
In any event, just because Dr. Benton Quest is a prominent evolutionary
scientist does not mean that his personal opinion can substitute for
scientific evidence.

KLOB: And as Dave himself quoted later in his post: "Prof Coyne insisted,
however, that the moths are almost certainly an example of natural
selection...." In other words, the moths still support evolution in general
and natural selection in particular; it's just the exact cause that is now
in question.

DJT: What do you mean by saying that the moths "support evolution"?

I would have thought that was obvious. Evolution is defined as the change
in frequency of one or more genes within a population of a living organism.
Since an organism's phenotype is determined by its genotype, any change in
the frequency of an observable morphological trait -- like light or dark
body color -- must be accompanied by a change in gene frequency as well.
The definition of evolution does not care how the change occurred, only that
it did. As such, a shift in the body color from light to dark to light
within populations of the peppered moth -- regardless of the exact cause or
mechanism -- is by definition evolutionary change. Such a change,
especially if it appears to be caused by a change in the environment, would
support the validity of the concept of evolution.

DJT: There are certainly natural variations taking place - but variation is
common to creationary and evolutionary theories.

Actually, you are using "variation" in a way that is different from how
evolutionary science uses it. And while I cannot say that this is the
creationist definition of the term, I have seen other creationists use it in
this same way.

You are using "variation" as a verb, to indicate a change in observable
morphological traits. Evolutionary science uses it as a noun, to indicate
the diversity of traits possible within a population of an organism. As
such, whereas when you say "variation" you mean the change from light to
dark to light, when an evolutionist says it he means both the light and dark
body colors together, since both are traits that can be found in any
population of peppered moth. Such a definition makes no mention of change,
so when traits are observed to change an evolutionist calls such change
evolution, as per the definition given earlier. So while you attempt to
separate evolutionary change from the observed change in traits within a
population, in point of fact when you say "variation" you mean evolution,
whether you realize it or not.

DJT: Why should you pick out "evolution" and not "creation"?

Most of my reasons are given above. Another reason has to do with the
history of the phenomenon. Long before Kettlewell did his experiments it
was known by observation that the shift in body color was being caused by
some sort of selective pressure brought about by the change in the
environment. Kettlewell was simply trying to identify the selective

Besides, "creation" is absurd unless you want to claim that the peppered
moth incident was a miracle staged by God in an attempt to delude poor
atheist evolutionists, in which case I would want to see your evidence in
support of this claim.

DJT: What do you mean by saying that the moths "still support ... natural
selection in particular"?

Again, that should be obvious. Traits and genes do not change frequency on
their own; there has to be a cause for it. The best and quickest cause is
to remove from a population those individuals who have certain traits while
leaving those individuals with other traits alone. This is the basic
definition of natural selection. Something removed white moths from the
population and left black moths alone, then later that same something or a
different something began to remove black moths from the population while
leaving white moths alone. We may not now know what those somethings are,
but the result is still natural selection and is still in keeping with the
conclusions based on the observations made before Kettlewell performed his

DJT: What are the selective forces?

Since the old theory has been refuted, we will need time to propose and test
new theories.

DJT: [hint: we have no idea! - is that a disallowed argument from

It is the way you mean it: the selective pressure is currently unknown,
therefore natural selection is impossible. However, since we have good
theoretical reasons for believing natural selection had been at work, the
lack of specific selective forces is not fatal. If, however, you can
provide evidence that contradicts natural selection as the best explanation,
then that would be different.

DJT: None of Kettlewell's reports of birds selectively eating moths carry
any weight.

Actually, that's not true; you are simply engaging in the typical
creationist exercise of blowing anything that you feel is a critique of
evolution way out of proportion. The design flaws in Kettlewell's
experiments make it difficult, if not impossible, to apply the results he
obtained to nature, but the results themselves are not being questioned. No
one denies that under the conditions of Kettlewell's experiments avian
predation serves as the main -- if not sole -- selective pressure; they just
deny that those conditions accurately reflect what happened in nature.
Also, no one has denied that avian predation -- or for that matter any form
of predation -- had absolutely no selective effect; they simply deny that it
was the sole, main or even an important effect.

DJT: What is the rational basis for saying that the moths give us
any knowledge of natural selective forces?

See above. To summarize: the moths showed a change in the frequency of the
light and dark body color traits in response to a change in the environment.
This environmental change caused first white moths to be removed from the
population, then latter black moths. If we do the right experiments, we
should be able to not only verify this basic observation, but also identifiy
the cause or causes. It is that simple.

DJT: The Dawkins comment is a massive understatement - bearing in mind that
Kettlewell made so much of having obtained "Darwin's missing evidence".

Hardly. Dawkins is merely saying, "So Kettlewell was wrong about the cause;
he was right about the mechanism and in any event the moths establish the
observational veracity of the fact of evolution." But keep on whipping this
dead horse if it makes you feel any better, David.

KLOB: So, is Dave saying that evolutionary scientists are not permitted to
be wrong, or to make mistakes? And is Dave implying that the peppered moth
is the sole evidence in support of natural selection and evolution? I would
hope that the answer to both questions is "no", yet the above statement
would suggest that he would answer "yes".

DJT: Evolutionary scientists ARE permitted to make mistakes! Furthermore,
I expect scientists (like everyone else) to learn from their mistakes.
Dawkins comment suggests to me that he has not learned from this mistake
from the past.

That's because you think the mistake is to accept evolution as a fact,
rather than the misidentification of the cause of the evolutionary change in
the peppered moth populations.

KLOB: As for Dawkins, all attempts to "spin" his comment aside, all he said
("But, in any case, nothing momentous hangs on these experiments.") was
exactly what every evolutionists on this list has said about this issue: So

DJT: Kettlewell announced his findings to the world with a fanfare: here is
"Darwin's missing evidence".

So he exaggerated the significance of his findings; what does this have to
do with the veracity of evolution? Are you suggesting that over enthusiasm
should be immediate grounds for questioning the veracity of a theory?

DJT: The experiments have remained as the ONLY good example of known forces
of natural selection affecting the genetic makeup of a breeding population.

Pardon my German, but pure, unadulterated cow chips! Since phenotype is
linked directly to genotype, any alteration in the observable morphological
traits of a breeding population MUST be accompanied by a change in the
genetic makeup of that population. As such, any experiment or observation
that tracks a change in phenotype as the environment changes is an example
of "natural selection affecting the genetic makeup of a breeding

DJT: Yes, there are over a hundred other examples of "natural selection" -
but in no case do we have the same clear link between identifiable selection
forces and the genetic make-up of organisms.

On the contrary, there are examples in which we have a better understanding
of the "link between identifiable selection forces and the genetic make-up
of organisms" than the peppered moth, especially now. Here are four of
them: heavy metal toxicity resistence in plants, antibiotic resistence in
bacteria, insecticide resistence in insects and the classical fruit fly
experiments. Oh yah, and recent experiments linking change in beak sizes of
Galapagos finches with climatic change.

What do you consider to be a "clear link"?

DJT: That is why Steve Jones described the Peppered Moth story as
"Evolution's best evidence".

No, he said that because, before now, it was the simplest, most
straight-forward example. Besides, he said "best evidence", whereas you are
saying "only evidence"; I'm surprised at how uninformed and naive you are
about this.

KLOB: Perhaps Dave is disappointed that Dawkins did not rise up in hellish
fury to crush this impudent reporter for even daring to question the
doctrine of evolution.

DJT: No. Dawkins appears to bite his tongue and count to 19 when such
impudence presents itself!

My point of course was that David's original reaction seemed to be one of
disappointment at Dawkin's reaction. Since Dawkin's reaction was subdued,
it was safe to assume that David was expecting a more energetic response.

Kevin L. O'Brien