Virtually every high school and college biology text book introduces its readers to the process of evolution by natural selection using the example of the phenomenon of industrial melanism, or the spread of dark forms of certain moth species in areas downwind of manufacturing centers.[1] They routinely cite experiments by H. B. D. Kettlewell (1955, 1956, 1958) as having established that the spread of dark forms is due to crypsis, or the protective value of dark coloration against visual predators in soot-darkened environments. Yet despite the frequency with which Kettlewell's investigations are cited by textbooks, the popular press, and scholarly discussions of evolutionary biology, they have been largely ignored by historians of science.[2] I propose to conduct an in-depth historical study of Kettlewell's work that will culminate in the form of a book (outline below). After a brief introduction, the proposal identifies the importance of this research with regard to traditional issues in the history and philosophy of science, and the pedagogy of science. Next, it provides a brief overview of my research so for. Finally, it concludes with a brief summary emphasizing the relevance of this study for science education.
1. Introduction
Henry Bernard Davis Kettlewell (1907-1979) was a medical practitioner during WWII with a life long interest in the Lepidoptera. In the late 1940s and early 50s, Kettlewell became associated with the Oxford School of Ecological Genetics, headed by E. B. Ford, devoted to the study of genetics in natural populations. This affiliation acquainted Kettlewell with a number of other brilliant scientists, including A. J. Cain, C. Darlington, R. A. Fisher, J. B. S. Haldane, J. Huxley, P. Sheppard, A. Hardy, and N. Tinbergen.
Kettlewell is most famous for his work on the phenomenon of industrial melanism, which refers to a rapid rise in the frequencies of dark (melanic) forms in several moth species in areas downwind of industrial centers, apparently in response to pollution. In a series of elegant investigations and a field survey conducted on the Peppered Moth, Biston betularia, during the years 1952-57, Kettlewell established that the rise in melanic forms was a consequence of selection: dark forms become more common in polluted areas because dark coloration in soot-darkened environments makes them less visible to avian predators. Kettlewell's experiments further documented that melanic forms were at a selective advantage of .40 in polluted environments relative to pale forms, well in excess of what most scientists at the time thought was possible in nature. The dramatic nature of Kettlewell's results most surely played a role in what Stephen J. Gould has dubbed the "hardening of the evolutionary synthesis" (Hagen 1999), and thus explains part of their acclaim among scientists at the time who were looking for examples of the pervasive role of selection in nature. Kettlewell's investigations are also widely regarded as an extremely straightforward demonstration of both natural selection and how scientific experiments are conducted, making them a natural candidate for textbooks. It would be hard to overstate how famous these investigations have become-they are routinely cited as among the most convincing demonstrations of natural selection, and are a favorite example of philosophers of biology who discuss the nature of selection (e.g. Brandon 1990, pp. 22-23).
2. Outstanding questions
As part of my dissertation I developed a case study of Kettlewell's early work as part of a broader analysis of the role of selection experiments in evolutionary biology (Rudge 1996). This initial historical analysis focused on identifying the experimental and theoretical contexts of Kettlewell's investigations, the design of his experiments, and his results. The associated philosophical analysis identified the arguments Kettlewell provided for eight specific conclusions and the respective roles of experiments and other forms of inquiry in his studies. In the course of doing these analyses, I discovered that the story textbooks routinely tell about Kettlewell's investigations grossly oversimplify a complex episode (see Rudge 1999, 2000, 2003, m.s.).
My initial study of the published record acquainted me with a number of intriguing historical questions that fell outside the scope of my dissertation concerning how and why this episode has become so renown in biology. There are some interesting and straightforwardly biographical questions that suggest themselves, such as what influence Kettlewell's medical training or his work on the use of radioactive isotopes in the study of locust migration in South Africa had on his later investigations on the Peppered Moth.
Perhaps most intriguing, however, is an apparent disparity between the reception these investigations have had with regard to public at large and Kettlewell's scientific colleagues. Initially scientists and laymen alike acclaimed Kettlewell's investigations. This reaction was precipitated in part by straightforwardly epistemic features, such as the elegance of his investigations and the magnitude of his results. But it was also due in no small measure to Kettlewell's own efforts as a popularizer of his work--in the course of doing research at the Kettlewell archive at Wolfson College in Oxford (noted below) I discovered an extensive correspondence that details Kettlewell's numerous lectures, radio and television appearances, as well as how he used films made with the assistance of Niko Tinbergen, to draw attention to the importance of his research. It is interesting to notice that while the public appeal of Kettlewell's investigations has strengthened over time (indeed people who know little else about evolutionary biology are generally familiar with Kettlewell's investigations), Kettlewell's colleagues became disenchanted with them. For instance, Philip Sheppard had reservations about certain aspects of the design of Kettlewell's experiments (particularly the elevated densities of moths used), reservations that led to his decision to repeat Kettlewell's investigations with Sir Cyril Clarke (Clarke and Sheppard 1963, 1966). It is striking to consider as well, that despite the fame of his investigations and several demonstrations made for the Royal Society, Kettlewell was never elected an FRS, in contrast to many of his colleagues associated with the Oxford School of Ecological Genetics, including Ford, Sheppard, Hardy, Cain, and Tinbergen.
As indicated above, there are also more general questions to be addressed regarding the popularization of this episode, and in particular, Kettlewell's own role in publicizing his work. Why have Kettlewell's investigations achieved such prominence in the popular press and biology textbooks in contrast to the significance generally attributed to them by scientists? Does, for instance, the prevalence of textbook citations to Kettlewell's studies reflect the intuitive character of the example, the relative ease with which students can grasp notions of bird predation and camouflage? Or can the reception of Kettlewell's work be understood (in part) in the context of the growth of the environmental movement in this country and concerns about pollution? What was the importance of these investigations in the context of debates about the teaching of evolution vs. creationism? Can the popularity of Kettlewell's studies be explained in part because they can be interpreted in isolation from more contentious issues concerning speciation and evolution? Does the fact that Kettlewell studied the differences between black and pale forms during a time of racial unrest in this country explain any aspects of how the study is presented or its reception? From a more explicitly philosophical point, a study of Kettlewell's investigations also promises insight into the nature of experimentation in general and how experiments in biology differ from investigations in other sciences.
This episode is also important from the standpoint of science pedagogy for three reasons. (1) A thorough study of Kettlewell's investigations and how they have been received also provides a specific example with which to discuss more general science policy issues concerning the teaching of evolution and the portrayal of science to introductory students (Rudge 2000, 2004). (2) As noted above, an analysis of this episode promises insight into the nature of textbook accounts of science, such as how and why particular episodes are chosen over others (Kettlewell's was one of several examples that were available to textbook writers-why did they choose his studies over others?). (3) And, perhaps most interesting to me as a philosopher, how much can a textbook account differ from the historical episode without compromising its value in explaining the actual practice of science?
3. Preliminary work
Since defending my dissertation in July 1996, I have continued to collect further historical materials on Kettlewell from many different sources. While at Texas A&M University, I found complete collections of several ancient London entomological journals (The Entomologist, The Entomologist's Record and Journal of Variation, The Entomologist's Monthly Magazine) that provide a wealth of historical material bearing on the context of Kettlewell's investigations, from the first reports of melanic moths increasing in frequency to active debates among amateur and professional entomologists regarding the significance of this trend, and in particular, its cause. These journals also provide information on Kettlewell's activities as an entomologist, including minutes of societies he belonged to and sporadic articles written by Kettlewell prior to his involvement with E.B. Ford. I spent a full day at the Julian Huxley Archive, Woodson Research Center, Rice University, Houston, TX on May 21, 1997, where I, with the generous assistance of Nancy Booth, examined Kettlewell's extensive correspondence with Julian Huxley, with whom Kettlewell collaborated in the writing of two separate books (Kettlewell wrote a section on his work on industrial melanism for the second edition of Huxley's (1964) Evolution the Modern Synthesis, they also worked together on (1965) Charles Darwin and His World).I visited this archive a second time during a brief trip to Rice University on 20 Feb 1998.
Perhaps most importantly, I spent a full month in England during July of 1997 at Kettlewell archive at Wolfson College[3] and also the Bodleian, where the papers of Kettlewell's colleagues E. B. Ford, Niko Tinbergen and Cyril Darlington are archived. During the trip I also met with several of Kettlewell's surviving colleagues, including Sir Cyril Clarke, Professors R. J. Berry and Lawrence Cook, and the Honorable Miriam Rothschild, among others. (I made this trip with the assistance of an international travel grant of $800 awarded to me by the Office of the Assistant Provost for International Programs at Texas A&M University.) (A detailed summary of the results of this trip is available here.) I spent a month in May 2001 in the American Philosophical Society's library in Philadelphia, where the papers of two more important colleagues of Kettlewell, Philip Sheppard and A. J. Cain have been archived. I also spent another month at Oxford during May 2003, in which I followed up on my previous initial study of Kettlewell's papers and also examined items specific to how Kettlewell's work has been used to teach science.
4. Conclusion
Kettlewell's work represents, in many ways, the culmination of two separate traditions in biology-- a naturalist tradition associated with amateur lepidopterists, moth collectors, and naturalists; and an experimental tradition exemplified by the ecological geneticists associated with the Oxford School of Ecological Genetics. A focused study on Kettlewell would aid in our understanding of many of the other figures of this school, with whom he carried on an extensive correspondence. A study of Kettlewell's investigations also promises insight into the nature of experimentation in general and how experiments in evolutionary biology differ from investigations in other sciences. Perhaps most importantly, a study of this episode promises insight into the nature of how science is portrayed in science textbooks, both from the standpoint of how exemplars are chosen and how they are simplified for use in teaching.
To summarize, the present document proposes a focused in-depth study of Kettlewell's investigations and their reception by the scientific community and the public at large, which will culminate in the form of a book. In several ways this represents a logical extension of previous work I have done on this episode. The case study I have developed provides a fairly comprehensive basis for understanding the experimental and theoretical contexts of Kettlewell's work, his investigations and his results. My research on this episode has also acquainted me with a number of other fascinating historical issues associated with this episode, which, although falling outside the scope of my dissertation, deserve further attention. A study of the popular reception of Kettlewell's investigations, and in particular, Kettlewell's own role in the publicizing of his work, promises insight into the process of science and how it is portrayed.
Beyond the historical and philosophical interest this episode clearly holds, pursuing this research has obvious implications for science pedagogy. (1) Scholars in science education have drawn attention to how the abbreviated treatment textbooks provide on specific examples of natural selection can lead to a "very superficial handling of key idas and lack of attention to alternative ideas" on the part of science teachers (Aleixandre 1994). (2) A number of scholars (e.g. Monk and Osborne 1997) have emphasized the importance of using examples from the history and philosophy of science in the teaching of science. Kettlewell's work is one of several routinely used by science educators to teach the concept of natural selection, and a number of authors have stressed how the historical, sociological and philosophical aspects of this episode in particular make it especially appropriate for use in science teaching (e.g. Hagen 1993, 1996; Rudge 2000, 2003, 2004). (3) As noted above, Kettlewell's work is also intriguing in that the depiction of his research as an exemplar of how to do science contrasts markedly with its reception among his colleagues. This raises interesting questions concerning the extent to which a textbook account is/should be constrained by historical and scientific detail, whether the pedagogic needs of teachers and students should override attention to accuracy, and whether we do students a disservice in not portraying science in its historical and sociological context, in all its "messy" detail. These are the issues this study will explore.
1. For a nice overview of Kettlewell's investigations including photographs of the different forms of the moth, see the website maintained by Chris Young at Mt. Angel Seminary here.
2. Joel Hagen and I have each written both historical (Rudge 1999, 2003, m.s.; Hagen 1999) and science education (Rudge 2000, 2003, 2004; Hagen 1993, 1996) articles devoted to this episode. Three biologists have discussed this episode: John Turner wrote a short biography on Kettlewell (Turner 1980), and R. J. Berry , a former colleague of Kettlewell, has published a brief review article of studies on industrial melanism that contains some additional historical material (Berry 1990); more recently, Michael Majerus (1998) published a major work on melanism that includes a discussion of the Peppered Moth story (see Chapters 5 and 6). The episode has been of perennial interest to creationists, advocates of intelligent design (e.g. Wells 2000) and more recently, a popular science writer (Hooper 2002).
3. The address of the web site associated with this archive is:
REFERENCES
Aleixandre, M. (1994) "Teaching Evolution and Natural Selection: A Look at Textbooks and Teachers." Journal of Research in Science Teaching 31:519-535.
Berry, R. J. (1990). Industrial melanism and peppered moths (Biston betularia (L)) Biological Journal of the Linnean Society 39:301-22.
Brandon, R. N. (1990) Adaptation and Environment. Princeton: Princeton University Press.
Clarke, C. and Sheppard, P. (1963) "Frequencies of melanic forms of the moth Biston betularia L. on Deeside and in adjacent areas. Nature 198:1219.
-----. (1966) A local survey of the distribution of industrial melanic forms in the moth Biston betularia and estimates of the selective values of these in an industrial environment. Proceedings of the Royal Society B 165:424-39.
Ford, E. B. (1937) Problems of heredity in the Lepidoptera. Biological Reviews 12: 461- 503.
Hagen, J. (1993) Kettlewell and the Peppered Moths Reconsidered. Bioscene 19 (3):3-9.
-----. (1996) Kettlewell and the Peppered moths reconsidered: An integrated approach to learning evolutionary principles. in Hagen, J., Allchin, D. and F. Singer (eds.) Doing Biology. New York: Harper Collins.
-----. (1999) Retelling Experiments: H.B.D. Kettlewell's Studies of Industrial Melanism in Peppered Moths. Biology and Philosophy 14:39-54.
Hooper, J. (2002) Of Moths and Men: An Evolutionary Tale. W.W. Norton & Company: New York.
Kettlewell, H. B. D. (1955) "Selection experiments on industrial melanism in the Lepidoptera" Heredity 9:323-342.
-----. (1956) "Further selection experiments on industrial melanism in the Lepidoptera" Heredity 10:287-301.
-----. (1958) "A survey of the frequencies of Biston betularia (L.) (Lep.) and its melanic forms in Great Britain" Heredity 12:51-72.
-----. (1973) The evolution of melanism: The study of a recurring necessity. Oxford: Clarendon Press.
Majerus, M. (1998), Melanism: Evolution in Action. Oxford: Oxford University Press.
Monk, M. and Osborne, J. (1997) "Placing the History and Philosophy of Science on the Curriculum: A Model for the Development of Pedagogy." Journal of Research in Science Teaching 34:405-424.
Rudge, D. (1996), A Philosophical Analysis of the Role of Selection Experiments in Evolutionary Biology. Ph.D. dissertation. University of Pittsburgh.
-----. (1998) A Bayesian Analysis of Strategies in Evolutionary Biology. Perspectives on Science 6(4):341-360.
-----. (1999) Taking the Peppered Moth with A Grain of Salt. Biology and Philosophy 14: 9-37.
-----. (2000) "Does Being Wrong Make Kettlewell Wrong for Science Teaching?" Journal of Biological Education 35 (1):5-11.
-----. (2001) Kettlewell From an Error Statistician's Point of View. Perspectives on Science 9 (1):59-77.
-----. (2002) Cryptic Designs on the Peppered Moth. (Review of Jonathan Well's Icons of Evolution) International Journal of Tropical Biology and Conservation (Revista de Biología Tropical) 50 (1):1-7.
-----. (2003) The Role of Photographs and Films in Kettlewell's Popularizations of the Phenomenon of Industrial Melanism. Science & Education 12 (3):261-287.
-----. (2004) Using the History of Research on Industrial Melanism to Help Students Better Appreciate the Nature of Science Pp. 761-772 and The Mystery Phenomenon: Lesson Plans Pp. 773-811. In Metz, D. (ed.) Proceedings of the Seventh International History, Philosophy and Science Teaching Conference.
-----. (m.s.) Did Kettlewell Commit Fraud? Examining the Evidence- submitted to Public Understanding of Science.
Schaffner, K. 1993. Discovery and Explanation in Biology and Medicine. Chicago: University of Chicago Press.
Turner, J. 1980. "Kettlewell, Henry Bernard Davis" pp. 469-71 in Holmes, F. ed. The Dictionary of Scientific Biography. New York: Charles Scribner's Sons Inc.
Wells, J. (2000) Icons of Evolution: Science or Myth? Why Much of What We Teach About Evolution is Wrong. Regnery Press: Washington, D.C.
Theme of book: Why does a particular scientific problem take on importance among scientific and other communities? Why does one investigation assume prominence while others languish?
You may contact Dave Rudge either by email, by phone (616)-387-2779 or by fax (616)-387-5609.
Dave Rudge's Home Page.
The Department of Biological Sciences's Home Page.
The Mallinson Institute for Science Education's Home Page.
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Last updated on 3 Dec 2007.