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Goodbye, Peppered Moths:
A classic evolutionary story comes unstuck
by Carl Wieland
(First published in Creation Ex Nihilo, 21(3):56, June - August 1999)
The 'textbook story' of England's famous peppered moths (Biston
goes like this. The moth comes in light and dark (melanic) forms.
the Industrial Revolution darkened the tree trunks, mostly by killing the
light-coloured covering lichen (plus soot).
The lighter forms, which had been well camouflaged against the light
background, now 'stood out', and so birds more readily ate them.
the proportion of dark moths increased dramatically. Later, as pollution
cleaned up, the light moth became predominant again.
The shift in moth numbers was carefully documented through catching them
traps. Release-recapture experiments confirmed that in polluted forests,
of the dark form survived for recapture, and vice versa. In addition,
were filmed preferentially eating the less camouflaged moths off tree
The story has generated boundless evolutionary enthusiasm. H.B.
who performed most of the classic experiments, said that if Darwin had
this, 'He would have witnessed the consummation and confirmation of his
Actually, even as it stands, the textbook story demonstrates nothing more
gene frequencies shifting back and forth, by natural selection, within
created kind. It offers nothing which, even given millions of years,
the sort of complex design information needed for ameba-to-man evolution.
Even L. Harrison Matthews, a biologist so distinguished he was asked to
the foreword for the 1971 edition of Darwin's Origin of Species, said
that the peppered moth example showed natural selection, but not
However, it turns out that this classic story is full of holes anyway.
moths don't even rest on tree trunks during the day.
British scientist Cyril Clarke investigated the peppered moth for 25
saw only two in their natural habitat by day - no other researchers have
any. Kettlewell and others attracted the moths into traps in the forest
with light, or by releasing female pheromones - in each case, they only
at night. So where do they spend the day? Clarke writes, 'The latest
that they rest on the leaves in the top of trees, but it's not really
way, they're very good at hiding.'2
The moths filmed being eaten by the birds were laboratory-bred ones
onto tree trunks by Kettlewell; they were so languid that he once had to
them up on his car bonnet (hood).3
And all those still photos of moths on tree trunks? One paper described
was done — dead moths were glued to the tree.4 University of
Massachusetts biologist Theodore Sargent helped glue moths onto trees for
NOVA documentary. He says textbooks and films have featured 'a lot of
Other studies have shown a very poor correlation between the lichen
and the respective moth populations. And when one group of researchers
dead moths onto trunks in an unpolluted forest, the birds took more of
(less camouflaged) ones, as expected. But their traps captured four times
many dark moths as light ones - the opposite of textbook predictions!7
University of Chicago evolutionary biologist Jerry Coyne agrees that the
peppered moth story, which was 'the prize horse in our stable', has to be
He says the realization gave him the same feeling as when he found out
Santa Claus was not real.5
Regrettably, hundreds of millions of students have once more been
indoctrinated with a 'proof' of evolution which is riddled with error,
1.H. Kettlewell (1959), 'Darwin's missing evidence' in Evolution and the
fossil record, readings from Scientific American, W.H. Freeman and
Co., San Francisco, 1978, p. 23.
2.C.A. Clarke, 'Evolution in reverse: clean air and the peppered moth',
Biological Journal of the Linnean Society 26:189–199, 1985.
3.Calgary Herald, March 21, 1999, p. D3. Return to text.
4.D.R. Lees & E.R. Creed, 'Industrial melanism in Biston betularia: the
role of selective predation', Journal of Animal Ecology 44:67-83, 1975.
5.J.A. Coyne, Nature 396(6706):35-36.
6.The Washington Times, January 17, 1999, p. D8.
7.D.R. Lees & E.R. Creed, ref. 4.
8.Unfettered by evolutionary 'just so' stories, researchers can now look
the real causes of these population shifts. Might the dark form actually
have a function, like absorbing more warmth? Could it reflect conditions
in the caterpillar stage? In a different nocturnal moth species, Sargent
found that the plants eaten by the larvae may induce or repress the
expression of such 'melanism' in adult moths (see Sargent T.R. et al in
M.K. Hecht et al, Evolutionary Biology 30:299-322, Plenum Press,
New York, 1998).
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