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113Re: [IntelligentDesignUpdate] Re: NYTimes.com Article: 'Of Moths and Men': The Moth That Failed

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  • Tom Curtis
    Sep 25, 2002
      In my last post I neglected to point out that I had excluded certain figures, and why. I wrote:
      > Thus, between 27/6 and 30/6, an average of 40 wild moths were caught per day;
      > while between 1/7 and 5/7, and average of 95.2 wild moths where caught each day;
      > more than double.
      Kettlewell collected (and recorded) moths on the 25th (9) and 26th (144) of June as well. The very low figure for the 25th is unexplained, but including it would improve my argument rather than making it worse. I believe the high figures for the second night reflect the lack of previous significant trapping. Peppered moths only have short lifespans as adults, but in the absence of significant trapping, many would survive several days in the wood. The commencement of trapping would, therefore, collect a large number of individuals, but thereafter, trapping would mostly collect individuals that had arrived (or hatched) in the wood from the previous day.

      In the meantime, I have just read Nic's review at Amazon, and it is very good. This section is particularly relevant to my discussion:

      Hooper does come up with a few arguments that not even the creationists have proposed -- most importantly, that Kettlewell faked his results, or almost as bad, unconsciously mislead himself. This is despite the fact that the predation and mark-release-recapture experiments have been repeated by other researchers and have in the main confirmed his results (see the articles by Cook, Grant, and the books by Majerus 1998 and 2002 for detailed reviews). The most astounding passage in Of Moths and Men occurs when Hooper spends a paragraph "squinting" at the tables in Kettlewell's paper, and she notes that Kettlewell's moth recapture numbers increase suddenly on July 1, 1953. The implication is that Kettlewell fudged things somewhere.

      But a modicum of investigation shreds Hooper's fraud hypothesis. What Hooper fails to look at seriously was that when Kettlewell released more moths, he recaptured more. Kettlewell started releasing far more moths on June 30th, and started catching far more moths on the morning of July 1st. In fact, when one does a linear regression, one discovers that "number of moths released" explains 80% of the variance in "number of moths recaptured". This is a nice strong linear relationship. Fraud is not a necessary explanation. Why didn't Hooper realize the obvious answer? Later in the book, Sargent keys off the same change in numbers, and he too mysteriously ignores the obvious explanation -- as in most of the book, Sargent's word is taken as gospel and is substituted for rigorous scientific evaluation.


      Tom Curtis
      ----- Original Message -----
      From: Nic Tamzek
      To: IntelligentDesignUpdate@yahoogroups.com
      Sent: Monday, September 23, 2002 2:26 PM
      Subject: [IntelligentDesignUpdate] Re: NYTimes.com Article: 'Of Moths and Men': The Moth That Failed

      Someone should give him Bruce Grant's review of Hooper, quoted at
      t.o. here:



      Science 297, 940-941 (2002)

      Sour Grapes of Wrath

      A review by Bruce S. Grant

      Of Moths and Men: Intrigue, Tragedy and the Peppered Moth
      Judith Hooper
      Fourth Estate, London, 2002. 397 pp. £15.99. ISBN 1-84115-392-3.

      Of Moths and Men The Untold Story of Science and the Peppered Moth
      Norton, New York, 2002. 397 pp. $26.95, C$38.99. ISBN 0-393-05121-8.

      Mark Twain once quipped that reports of his death had been
      Recent reports exaggerate the death of industrial melanism as an
      exemplar of
      natural selection. The latest is Judith Hooper's Of Moths and Men,
      promises "the untold story of science and the peppered moth." What it
      delivers is a quasi-scientific assessment of the evidence for natural
      selection in the peppered moth (Biston betularia), much of which is
      cast in
      doubt by the author's relentless suspicion of fraud. This is
      Hooper is a gifted writer. In places, her prose is quite enjoyable,
      brilliant. But, sadly, the book is marred by numerous factual errors
      and by
      misrepresentations of concepts and controversies.

      The fundamental problem is Hooper's failure to clearly distinguish the
      evidence for natural selection and the mechanism of selection. A dead
      with a knife in its back is evidence that a murder has been
      committed. An
      inability to establish beyond reasonable doubt the guilt of the
      suspect does not mean that the murder did not occur.

      Population geneticists define evolution as a change in allele (gene)
      frequency. Adult peppered moths come in a range of shades from
      mottled gray
      (pale) to jet black (melanic). We know from extensive genetic
      analysis that
      these phenotypes result from combinations of multiple alleles at a
      locus. Changes in the percentages of the phenotypes in wild
      populations are
      well documented. The changes continue and are observable even now. The
      steady trajectory and speed of changes in allele frequencies indicate
      this evolution results primarily from natural selection. J. B. S.
      original calculation of a selection coefficient was estimated from the
      number of generations it took for the melanic phenotype to effectively
      replace the pale phenotype during the 19th century. More detailed
      document recent changes. For example, near Liverpool, England, the
      phenotype declined from 93 to 18% in 37 generations (one generation
      year); this change is consistent with a 15% selective disadvantage to
      genotypes with the dominant (melanic) allele.

      We have amassed enormous records of changes in allele frequency in
      moth populations that cannot be explained in the absence of natural
      selection. But what is the mechanism of selection? Even the
      answer "we have
      no clue" would not invalidate the conclusion that selection has
      Fortunately, the circumstances have left clues.

      Geographic and temporal variations in the incidence of melanism
      with atmospheric levels of SO2 and suspended particles. (The
      are not perfect; gene flow by migration spreads alleles, even into
      populations where they are deleterious.) Light reflectance from tree
      declines as suspended particles increase. Across a range of
      backgrounds, the
      pale and melanic phenotypes are differently conspicuous to the human
      eye. As
      early as 1896, J. W. Tutt suspected that birds were selectively eating
      conspicuous phenotypes in habitats variously modified by industrial
      H. B. D. Kettlewell first tested Tutt's idea in the 1950s.

      It is on Kettlewell and his experiments that Hooper focuses her
      In a biography more akin to character assassination than to objective
      disclosure, she portrays Kettlewell as an insecure misfit so driven to
      please his "boss," E. B. Ford, that he is suspected (by Hooper) of
      his data. She bases her case on experimental design changes that
      himself described in his papers and on a sudden increase in the
      rate of marked moths released in polluted woodlands. Several obvious
      that Hooper left unexamined affect the size of moth catches, and her
      case is
      unconvincing. In addition, she presents it as if the very evidence for
      natural selection in peppered moths depends on the validity of
      experiments. But even the evidence for bird predation does not depend

      Fortunately, science assesses the correctness of work by testing its
      repeatability. Kettlewell's conclusions have been considered in eight
      separate field studies, of various designs, performed between 1966
      and 1987.
      Some of the design changes--such as reducing the density of moths,
      assigning moths to trees, altering locations on trees where moths were
      positioned, and positioning killed moths to control for differences in
      viability and dispersal--were made to correct deficiencies identified
      in his
      original experiments. L. M. Cook's regression analysis of fitness
      from these experiments plotted against phenotype frequencies at their
      various locations shows the studies to be remarkably consistent (1).

      Other mechanisms of selection have been proposed. An inherent
      advantage of melanic over pale phenotypes is consistent with the rise
      spread of melanism, but the widespread decline in melanism that
      followed the
      Clean Air Acts obviates that interpretation. Although the possibility
      remains that physiological differences might be facultative (changing
      conditions), so far no experimental work supports this idea. To date,
      selective predation by birds is backed by experiment.

      Hooper's book turns bizarre when she showcases American biologist T.
      Sargent as a wounded iconoclast whose career was stultified because
      Kettlewell dismissed his work. She argues that Sargent is now under
      because he questions the "classical explanation" for industrial
      Hooper garbles the controversy regarding background selection by
      moths, and
      she entertains Sargent's protracted speculation about phenotypic
      (He has offered no evidence that melanism is an induced character in
      peppered moths.) But most egregious is Sargent's assertion that
      studies in
      North America falsify the classical explanation. The history of
      melanism in
      American peppered moths--which are conspecific with Kettlewell's
      moths, not
      a separate species as Hooper indicates--closely parallels what has
      in Britain, and melanism is correlated in like manner with levels of
      atmospheric pollution (2). The American studies corroborate rather
      contradict the classical explanation.

      The case for natural selection in the evolution of melanism in
      moths is actually much stronger today than it was during Kettlewell's
      Textbook accounts should be expanded to reflect this newer
      information, and
      they should not cite Of Moths and Men as a credible resource.


      1. L. M. Cook, Biol. J. Linn. Soc. 69, 431 (2000).
      2. B. S. Grant, L. L. Wiseman, J. Hered. 93, 86 (2002).
      The author is in the Department of Biology, College of William and
      Williamsburg, VA 23187-8795, USA. E-mail: Geometrid@...


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