Of Moths and Men: Intrigue,
Tragedy and the Peppered Moth
by Judith Hooper
Fourth Estate: 2002. 397 pp. £15.99
Jerry A. Coyne
A colleague described the physician and
naturalist Bernard Kettlewell as “the best
naturalist I have ever met, and almost the
worst professional scientist I have ever
known”. And yet Kettlewell became one of
the best-known evolutionary biologists, for
his work produced the canonical example
of evolution in action: industrial melanism
in the peppered moth (Biston betularia). In
Of Moths and Men, the science journalist
Judith Hooper produces a lively history
of this work, illustrated with fascinating
but disturbing portraits of the principals.
These include the ambitious but insecure
Kettlewell, ill at ease in the rarefied atmos-
phere of Oxford University, and his mentor
E. B. Ford, a foppish, manipulative man
who used and misused Kettlewell in his own
quest for fame. Hooper contends that the
Biston story is not only wrong, but probably
fraudulent.
The scientific facts are familiar to biolo-
gists. The normal form of B. betularia
(known as typica) is white, speckled with
dark markings. In around 1850, a melanic,
all-black form produced by a dominant
mutation (carbonaria) became more numer-
ous in England, at the same time as a rise
in industrial pollution. By 1900, carbonaria
reached a frequency of nearly 100% in
manufacturing areas such as
Birmingham. There was a
parallel increase in indus-
trial areas of the United
States, although somewhat
later. These evolutionary
changes were reversed in
the middle of the century
when antipollution laws
took effect, and typica
once again became
predominant both in
Britain and in the
United States.
The rise of
melanism offered Ford and Kettlewell an
unparalleled chance to document and under-
stand natural selection in the wild. Ford
suggested, on the basis of breeding experi-
ments, that carbonaria was more resistant
than typica to pollution, and hence survived
better. As a naturalist, Kettlewell believed
that selection might be due to sharp-eyed
birds that preyed on the moths that were
most conspicuous in their local habitat.
Kettlewell tested his hypothesis in 1953.
After releasing marked typica and carbonaria
in a wood where trees were darkened by pol-
lution, he recaptured a much higher percent-
age of dark than light moths, implying
selective predation on typica. Two years later,
he obtained the opposite result in an unpol-
luted forest. Combined with observations of
the hunting behaviour of birds, and of the
distribution of the two forms in Britain,
these experiments seemed to provide Dar-
win’s ‘missing evidence’: a complete story
connecting ecological forces to evolutionary
change. Kettlewell gained instant fame, and
the Biston story was quickly installed in biol-
ogy textbooks, where it remains to this day.
Hooper suggests, however, that the
release experiments were
probably fudged to
achieve the desired
outcome. Unfortu-
nately, in her desire
to write a lepidopteran
‘whodunnit’, she advances a flimsy
conspiracy theory. Her evidence rests largely
on the fact that Kettlewell’s first experiment
began as a failure, for he recaptured too few
moths to show differential survival. His
forlorn letter to Oxford provoked a soothing
response from Ford: “It is disappointing
that the recoveries are not better… However,
I do not doubt that the results will be very
worth while.”
To a professional biologist this sounds
familiar; many of us have offered similar
consolation to students having a hard time
in the field. But to Hooper, Ford’s note is a
coded message telling Kettlewell to get the
right results at all costs. Sure enough, Kettle-
well’s recapture rate shot up, perhaps
because he tripled the number of moths
released. Hooper, however, finds this cause
insufficient. Using meteorological records,
she rules out a change in the weather, and
suggests that the increased recapture rate
reflected chicanery by Kettlewell — perhaps
he changed the experimental design in mid-
stream, or even mis-scored the moths. But
many factors other than the weather can
change recapture rates, including experi-
mental modifications, such as relocating
moth traps, that are completely innocuous.
Anyone with experience of fieldwork knows
how unpredictable such experiments can be.
It has been widely recognized that Kettle-
well’s experiments were indeed flawed.
Hooper enumerates the familiar problems:
Kettlewell used mixtures of wild-caught and
lab-reared moths, released them at the
wrong time of day onto unnatural resting
places, and so on. As a result,
the role of bird predation in
the evolution of melanism
remains unclear. But slop-
piness is not fraud. Eager
to push her theme of
“ambitious scientists
who will ignore the
truth for the sake of
fame and recogni-
tion”, she unfair-
ly smears a
brilliant nat-
uralist.
book reviews
Evolution under pressure
A look at the controversy about industrial melanism in the peppered moth.
Bernard Kettlewell was an enthusiastic naturalist
who loved to surround himself with his work.
Light
work?
The two
forms of the
peppered moth
make it ideal
for studies of
evolution.
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IT
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NATURE | VOL 418 | 4 JULY 2002 | www.nature.com/nature 19© 2002 Nature Publishing Group

Many of the problems with Kettlewell’s
experiments and the ‘classic’ Biston story
were first aired by the US biologist Ted
Sargent. Curiously, when turning from
Kettlewell to Sargent, Hooper’s criticality
evaporates. She claims that Sargent’s criti-
cisms of the moth work ruined his career by
making him a pariah, rejected by a scientific
establishment enamoured with Biston. But
this is hyperbole. Sargent’s career may have
languished because he often published in
little-known journals or (as Hooper notes)
refused to apply for grants — the kiss of
death for a US scientist.
Hooper also champions Sargent’s view
that industrial melanism was a case not of
evolution but of “phenotypic induction” —
a developmental change in the colour of
moths, presumably caused by the larval
ingestion of pollutants. But she conveniently
glosses over the simple and unassailable
fact that the light and dark alleles of
Biston segregate as mendelian variants
when tested under uniform experimental
conditions. Perhaps Hooper embraces the
induction theory because it makes for a bet-
ter story, but surely good science journalism
demands that drama takes a back seat to data.
Numerous scientific errors (the American
peppered moth is not B. cognataria but
B. betularia, the same species as in Britain,
for example), mar the book for biologists.
The biggest shortcoming, however, is
Hooper’s failure to emphasize that, despite
arguments about the precise mechanism of
selection, industrial melanism still repre-
sents a splendid example of evolution in
action. The dramatic rise and fall of the
frequency of melanism in Biston betularia,
occurring in parallel on two continents, is
a compelling case of evolution by natural
selection. No force other than selection
could have caused such striking and direc-
tional change. Hooper’s grudging admis-
sion of this fact occupies but one sentence:
“It is reasonable to assume that natural
selection operates in the evolution of the
peppered moth.”
This issue matters, at least in the United
States, because creationists have promoted
the problems with Biston as a refutation of
evolution itself. Even my own brief critique
of the story (Nature 396, 35–36; 1998)
has become grist for the creationists’ mill.
By peddling innuendo and failing to
distinguish clearly the undeniable fact
of selection from the contested agent of
selection, Hooper has done the scientific
community a disservice. n
Jerry A. Coyne is in the Department of Ecology
and Evolution, University of Chicago, 1101 East
57th Street, Chicago, Illinois 60637, USA.
Competition
between women
A Mind of Her Own: The
Evolutionary Psychology of
Women
by Anne Campbell
Oxford University Press: 2002. 402 pp.
£21.99, $40
Elizabeth Cashdan
This provocative book argues that competi-
tion among women has been an important,
yet largely ignored, force in human sexual
selection. Competition between males is
usually thought to be more intense than
female competition because greater male
variance in reproductive success means that
men are playing for higher stakes. But
Campbell suggests that this is misleading:
“The variance may not be as great as between
males but that is irrelevant because females
are not in competition with males, they are
in competition with other females.” Mothers
(not fathers) are critical to offspring sur-
vival, and differences among women in their
success in this endeavour have shaped the
way that women think, feel and behave.
The book opens with a sharp and satis-
fying critique of postmodernist biophobia
and a skilful rebuttal to those who distrust
evolutionary psychology’s scientific meth-
ods and fear its political implications. It
closes with an excellent in-depth account
of the evolutionary reasons for individual
variation. In between, Campbell shows us
how and why women compete.
Women are clearly less physically aggres-
sive and less risk-prone than men, but why?
Campbell rejects the belief that it is a “default
option that results from lower incentives
for competition” and attributes it instead to
women’s greater parental investment: they
have more to lose from violent and risky
behaviour. This behavioural difference,
she argues, is mediated by a sex difference
relating to fear of injury and a neuro-
chemistry that makes women better able to
inhibit aggressive impulses.
These arguments are extended in
Campbell’s discussion of sex differences in
dominance and status-seeking. The rewards
of high status “are just as great for females
as for males — arguably greater because
resources fuel the survival of offspring in
which they have already invested while for
males it merely buys a ticket in the copulatory
lottery of possible fatherhood”, she argues.
What differs, she continues, is not the
rewards, but the costs (the risk of injury).
This argument explains why women are less
prone to seek high status through aggressive
competition. It is also used to good effect in a
later chapter on women and crime, in which
Campbell explains why women commit
book reviews
20 NATURE | VOL 418 | 4 JULY 2002 | www.nature.com/nature
Lionesses Pacing in a Cage by Max Slovegt depicts
the experience of wild animals put on public
display. From Zoo: A History of Zoological
Gardens in the West by Eric Baratay and
Elisabeth Hardouin-Fugier (Reaktion Books,
£28, $40), recently translated from French.
Kept in captivity
© 2002 Nature Publishing Group