Bernard Kettlewell

Kettlewell was born in Howden, Yorkshire, and educated at Charterhouse School. During 1926 he studied medicine and zoology at Gonville and Caius College, Cambridge. During 1929 he began clinical training at St Bartholomew's Hospital, London, then during 1935 joined a general medical practice in Cranleigh, Surrey. He also worked as an anaesthetist at St. Luke's Hospital, Guildford. During World War II, from 1939 to 1945, he worked for the Emergency Medical Service at Woking War Hospital.{{cite web |url=http://www.wolfson.ox.ac.uk/library/archives/kettlewell/bio/ |title=Biographical Data on Henry Bernard Davis Kettlewell – Wolfson College |access-date=10 September 2007 }}

He emigrated to South Africa during 1949, and from then until 1954 was a researcher at the International Locust Control Centre at Cape Town University, investigating methods of locust control and going on expeditions to the Kalahari Desert, the Knysna Forest, the Belgian Congo, and Mozambique.

During 1952 he was appointed to a Nuffield Research Fellowship in the Department of Genetics of the Department of Zoology at Oxford University. Until 1954 he divided his time between South Africa and Oxford, then he gained the position of Senior Research Officer of the Department of Genetics and spent the rest of his career in Oxford as a genetics researcher. He was assigned to investigate peppered moth evolution under the supervision of E. B. Ford.

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His grant was to study industrial melanism in general and in particular the peppered moth Biston betularia which had been studied by William Bateson during the 1890s. Kettlewell's research from three surveys between 1952 and 1972 seemed to show a static pattern with a high frequency of the dark-coloured carbonaria phenotype in industrial regions, and the light coloured typica moths the most common in more rural areas. In the first of Kettlewell's experiments moths were released into an aviary to observe how insectivorous birds reacted. He showed that the birds ate the moths, and found that if the camouflage of the moths made them difficult for him to see against a matching background, the birds too had difficulty in finding the moths.{{cite web|url=http://www.streaming.mmu.ac.uk/cook/ |title=The Peppered Moth |access-date=10 September 2007 |first=Laurence |last=Cook |year=2003 |work=The Melanic Peppered Moth, Seminar to Post Grad Students |publisher=Manchester Metropolitan University |archive-url=https://web.archive.org/web/20070702152449/http://www.streaming.mmu.ac.uk/cook/ |archive-date=2 July 2007 |url-status=dead }} Most famously he then performed experiments involving releasing and then recapturing marked moths in polluted woodlands in Birmingham, and in unpolluted rural woods at Deanend Wood, Dorset, England.{{ cite web|url=http://www.blackwellpublishing.com/ridley/tutorials/The_theory_of_natural_selection__part_1_15.asp |title=The theory of natural selection (part 1) |publisher=Blackwell Publishing |access-date=12 July 2007 |url-status=dead |archive-url=https://web.archive.org/web/20070926222014/http://www.blackwellpublishing.com/ridley/tutorials/The_theory_of_natural_selection__part_1_15.asp |archive-date=26 September 2007 }} He demonstrated experimentally the efficiency of natural selection as an evolutionary force: light-coloured moths are more conspicuous than dark-coloured ones in industrial areas, where the vegetation is darkened by pollution, and are therefore easier prey for birds, but are less conspicuous in unpolluted rural areas, where the vegetation is lighter in colour, and therefore survive predation better. His experiment resulted in better understanding of industrial melanism and its effects on the evolution of species, and can be seen as an important example of urban evolution.{{cite journal |last=Bender |first=Eric |title=Urban evolution: How species adapt to survive in cities |journal=Knowable Magazine |publisher= Annual Reviews |date=21 March 2022 |doi=10.1146/knowable-031822-1 |doi-access=free |url=https://knowablemagazine.org/article/living-world/2022/urban-evolution-species-adapt-survive-cities |access-date=31 March 2022|url-access=subscription }}{{cite journal |last1=Diamond |first1=Sarah E. |last2=Martin |first2=Ryan A. |title=Evolution in Cities |journal=Annual Review of Ecology, Evolution, and Systematics |date=2 November 2021 |volume=52 |issue=1 |pages=519–540 |doi=10.1146/annurev-ecolsys-012021-021402 |s2cid=239646134 |issn=1543-592X|doi-access=free }}

J. B. S. Haldane was of the opinion that Kettlewell had attempted to capitalise on Haldane's own observations, made as early as 1924, of the statistical probability of rate of change from light to melanic forms of the peppered moth. In 1961, Haldane and his graduate student (and later wife) Helen Spurway told Canadian lepidopterist Gary Botting that they questioned Kettlewell's data since it too "nicely" approximated Haldane's 1924 statistical calculations. Botting and Haldane at that time shared the opinion that some genetic mechanism other than bird predation was at work."Preface," in Heather and Gary Botting,The Orwellian World of Jehovah's Witnesses (Toronto: University of Toronto Press, 1984Tihemme Gagnon, "Introduction," Streaking! The Collected Poems of Gary Botting (Miami: Strategic, 2013 However see alsoLaurence M. Cook and John R.G. Turner, "Fifty percent and all that: what Haldane actually said," Biological Journal of the Linnean Society, https://academic.oup.com/biolinnean/issue/129/3 2020, 129, 765–771 for a re-appraisal of Haldane's views.

The major argument was made by Theodore David Sargent, professor of zoology at the University of Massachusetts at Amherst. He reported that during 1965–1969 he attempted to perform similar experiment, and found that birds did not have preference on moth on either black or white tree trunks.{{cite journal|last=Sargent|first=T. D.|title=Cryptic moths: effects on background selections of painting the circumocular scales.|journal=Science|year=1968|volume=159|issue=3810|pages=100–1|pmid=5634373|doi=10.1126/science.159.3810.100|bibcode=1968Sci...159..100S|s2cid=32124765}}{{cite journal|last=Sargent|first=T. D.|title=Background Selections of the Pale and Melanic Forms of the Cryptic Moth, Phigalia titea (Cramer)|journal=Nature|year=1969|volume=222|issue=5193|pages=585–586|doi=10.1038/222585b0|bibcode=1969Natur.222..585S|s2cid=4202131}} He suspected that Kettlewell trained the birds to pick moths on tree trunk, where they were not normally present.

Further criticism of Kettlewell's peppered moth research came from Judith Hooper in her 2002 book Of Moths and Men,{{cite book|last=Hooper|first=Judith|title=Of Moths and Men : Intrigue, Tragedy & the Peppered Moth|url=https://archive.org/details/ofmothsmenevolut00hoop|url-access=registration|year=2002|publisher=Norton|location=New York|isbn=978-0-393-32525-6}}{{cite news|last=Kenney|first=Michael|title=Of dark moths, men and evolution|url=https://www.chicagotribune.com/2002/10/22/of-dark-moths-men-and-evolution/|access-date=10 December 2014|work=Chicago Tribune|date=22 October 2002}} in which she claims that Kettlewell's field notes could never be found and his experiments were fraudulent, reiterating Sargent's allegations that the experimental photographs were faked by planting dead moths on a log. She accuses Ford of being a Darwinian zealot who exploited Kettlewell's servitude{{cite web|title=Of Moths and Men|url=http://books.wwnorton.com/books/Of-Moths-and-Men/|publisher=W. W. Norton & Company, Inc.|access-date=10 December 2014|archive-url=https://archive.today/20141210045231/http://books.wwnorton.com/books/Of-Moths-and-Men/|archive-date=10 December 2014|url-status=dead}} and criticises scientists in general for credulous and biased acceptance of evolution.{{cite news|last=Smith|first=Peter D.|title=Of Moths and Men: Intrigue, Tragedy & the Peppered Moth|url=https://www.theguardian.com/books/2002/may/11/scienceandnature.highereducation|access-date=10 December 2014|work=The Guardian|date=11 May 2002}}

A review in EMBO Reports describes the book as "Hooper's exhilarating account of the public and private lives of an opinionated and powerful group of evolutionists, who contributed to this shameful episode in the study of evolution."{{cite journal|last=Dover|first=Gabby|title=Mothbusters|journal=EMBO Reports|year=2003|volume=4|issue=3|pages=235|doi=10.1038/sj.embor.embor778|pmc=1315906}} The book has also been widely quoted by creationists.{{cite news|title=Of moths and men|url=https://www.independent.co.uk/news/science/of-moths-and-men-85452.html|access-date=10 December 2014|work=The Independent|date=4 September 2003}} However, Hooper's various allegations have been refuted by the scientific community:{{cite journal|last=Cook|first=L. M.|title=The rise and fall of the Carbonaria form of the peppered moth.|journal=The Quarterly Review of Biology|year=2003|volume=78|issue=4|pages=399–417|doi=10.1086/378925|pmid=14737825|s2cid=26831926}}{{cite journal | last =Grant |first=B. S. | year = 2002 | title = Sour grapes of wrath| journal = Science | volume = 297| issue = 5583 | pages = 940–941 | doi=10.1126/science.1073593| s2cid = 161367302 }}{{cite book|last=Majerus|first=Michael E. N.|editor1-last=Fellowes|editor1-first=Mark|editor2-last=Holloway|editor2-first=Graham|editor3-last=Rolf|editor3-first=Jens|title=Insect Evolutionary Ecology|year=2005|publisher=CABI Publishing|location=Wallingford, Oxon|isbn=978-1-84593-140-7|pages=375–377|url=https://books.google.com/books?id=hS9V81dl1FEC|chapter=The peppered moth: decline of a Darwinian disciple}} David W Rudge summarised that "none of Hooper's arguments is found to withstand careful scrutiny"{{cite journal|last=Rudge|first=D. W.|title=Did Kettlewell commit fraud? Re-examining the evidence|journal=Public Understanding of Science|year=2005|volume=14|issue=3|pages=249–268|doi=10.1177/0963662505052890|pmid=16240545|s2cid=25525719|url=https://hal.archives-ouvertes.fr/hal-00571065/file/PEER_stage2_10.1177%252F0963662505052890.pdf}} and that all "these charges are baseless and stem from a fundamental misunderstanding of the nature of science as a process."{{cite journal|last=Rudge|first=David W.|title=Myths about moths: a study in contrasts|journal=Endeavour|year=2006|volume=30|issue=1|pages=19–23|doi=10.1016/j.endeavour.2006.01.005|pmid=16549216}}

Kettlewell's experiments have been vindicated by elaborate research,{{cite journal|last1=Cook|first1=L. M.|last2=Grant|first2=B. S.|last3=Saccheri|first3=I. J.|last4=Mallet|first4=J.|title=Selective bird predation on the peppered moth: the last experiment of Michael Majerus|journal=Biology Letters|year=2012|volume=8|issue=4|pages=609–612|doi=10.1098/rsbl.2011.1136|pmid=22319093|pmc=3391436|url=https://dash.harvard.edu/bitstream/handle/1/11210622/3391436.pdf?sequence=1}} and the genetic details of the evolutionary process established.{{cite journal|last1=van't Hof|first1=A. E.|last2=Edmonds|first2=N.|last3=Dalikova|first3=M.|last4=Marec|first4=F.|last5=Saccheri|first5=I. J.|title=Industrial Melanism in British Peppered Moths Has a Singular and Recent Mutational Origin|journal=Science|year=2011|volume=332|issue=6032|pages=958–960|doi=10.1126/science.1203043|pmid=21493823|bibcode=2011Sci...332..958V|s2cid=24400858}}{{cite journal|last1=Cook|first1=L. M.|last2=Saccheri|first2=I. J.|title=The peppered moth and industrial melanism: evolution of a natural selection case study|journal=Heredity|year=2012|volume=110|issue=3|pages=207–212|doi=10.1038/hdy.2012.92|pmid=23211788|pmc=3668657}}{{cite journal|last1=Van't Hof|first1=A. E.|last2=Nguyen|first2=P.|last3=Dalíková|first3=M.|last4=Edmonds|first4=N.|last5=Marec|first5=F.|last6=Saccheri|first6=I. J.|title=Linkage map of the peppered moth, Biston betularia (Lepidoptera, Geometridae): a model of industrial melanism|journal=Heredity|year=2012|volume=110|issue=3|pages=283–295|doi=10.1038/hdy.2012.84|pmid=23211790|pmc=3668655}}

Michael Majerus carried out extensive experiments, examining moths in the wild, to re-examine the findings of Kettlewell's experiments in the light of subsequent questions. His work, published posthumously in 2012, provided new data which answered criticisms and validated Kettlewell's methodology. Their analysis reaffirmed Kettlewell's conclusion that differential selection by birds using their eyesight to find prey was sufficient to explain the changes in melanism, and that this demonstrated the effectiveness of natural selection as an evolutionary force.

Because of vigorous field research, Kettlewell suffered from bronchitis, pneumonia, pleurisy and flu, along with heart problems. He fell off a birch tree in 1978 while conducting a field collection and fractured two vertebrae in his back. He never recovered from the injury. On 11 May 1979, he died, allegedly of an accidental overdose of a painkiller.{{cite book|last=Hooper |first=Judith |year=2002 |title=Of Moths and Men : Intrigue, Tragedy & the Peppered Moth |location=New York |publisher=Norton |isbn=978-0-393-32525-6}}Kettlewell, Henry Bernard Davis. Dictionary of Scientific Biography vol. 17, suppl. II, pp. 469–471 by J.R.G. Turner

• Darwin Medal (USSR) in 1959
• Mendel Medal (Czechoslovakia) in 1965
• Official Fellow of Iffley College (later Wolfson College) in 1965
• Elected Emeritus Fellow of Wolfson College 1974

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Category:1907 births

Category:1979 deaths

Category:20th-century English medical doctors

Category:20th-century British zoologists

Category:Alumni of Gonville and Caius College, Cambridge

Category:Drug-related deaths in England

Category:English lepidopterists

Category:Modern synthesis (20th century)

Category:People educated at Charterhouse School

Category:People from Howden

Category:Scientists from Yorkshire

Category:Academics of the Medical College of St Bartholomew's Hospital

Category:Medical scholars of the University of Oxford

Category:Academic staff of the University of Cape Town