Talk:Kettlewell's experiment

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This article is erroneous. Please refer to the following article for a factual depiction of Kettlewell's experiments. "Retelling Experiments: H.B.D. Kettlewell's Studies of Industrial Melanism in Peppered Moths" by Joel B. Hagen. —Preceding unsigned comment added by 142.103.93.213 (talk • contribs) 3 December 2007


 * It would help to say what parts are erroneous. I'm not that sure that we need an additional article on this topic but I'm not sure that we don't either. If we are going to keep it I hope it's current state is well below it's potential size and quality. Richard001 (talk) 01:34, 2 October 2009 (UTC)

Haldane JBS. A mathematical theory of natural and artificial selection (1924) - as reported by Cook & Saccheri (2012)
Currently, this assertion appears in this Wikipedia article:

"For example, J.B.S. Haldane estimated in 1924 that it would be impossible for selection to occur within such a short period of time.[1]"

This assertion is complete and utter nonsense. It is totally untrue. It is very misleading because, in fact, in 1924 Haldane estimated the exact opposite.

At first, I took this erroneous assertion at face value, assuming good faith on the part of the editor who made the assertion. Sometime later, I have read and re-read the cited 2012 paper by Cook & Saccheri, and the original 1924 paper by Haldane. Nowhere in the 2012 paper by Cook and Saccheri can I find anything that amounts to claiming that Haldane in 1924, or at any other time, 'estimated in 1924 that it would be impossible for selection to occur within such a short period of time'. Indeed, Cook and Saccheri would be unlikely to make such a claim given that Haldane on the seventh page of his original 1924 paper (thus on page 26 as published) stated the complete opposite, viz:

3. The dominant melanic form doubledayaria of the peppered moth Amphidasys betularia first appeared at Manchester in 1848. Some time before 1901 when Barrett (13) described the case, it had completely ousted the recessive variety in Manchester. It is required to find the least intensity of natural selection which will account for this fact.

 Table ll  {Wikipedia editor's note: NB, for the sake of brevity and the time needed to transpose this accurately, I have not included Table ll here but it may be seen in Haldane's 1924 original paper - see link below}

Assuming that there were not more than 1% of dominants in Manchester in 1848, nor less than 99% in 1898, we have from Table ll kn=16.58 as a minimum. But n=50, since this moth usually has one brood per year. ∴ k=.332 at least, i.e. at least 3 dominants must survive for every 2 recessives, and probably more: or the fertility of the dominants must be 50% greater than that of the recessives. Direct calculation step by step from equation (2.1) shows that 48 generations are needed for the change if k=.3 Hence the table is sufficiently accurate. After only 13 generations the dominants would be in a majority. It is  perhaps instructive, in view of the fact that attempts have been made to explain such cases by epidemics of mutation due either to the environment or to unknown causes, to note that in such a case one recessive in every five would have to mutate to a dominant. Hence it would be impossible to obtain true breeding recessives as was done by Bate (14). Another possible explanation would be a large excess of dominants begotten in mixed families, as occurs in human night-blindness according to Bateson (15). But this again does not agree with the facts, and the only probable explanation is the not very intense degree of natural selection postulated above.

Note in particular Haldane's concluding remark (my italics for emphasis) in the quoted paragraph here: ... the only probable explanation is the not very intense degree of natural selection postulated above. 'Not very intense degree of natural selection' is completely the opposite, of course, of the current assertion in the Wikipedia article that '... it would be impossible for selection to occur within such a short period of time'.

Assuming good faith, all I can conclude is that the editor who has made this erroneous assertion was confused by Haldane's remark about true breeding recessives as was done by Bate. To be clear, note that the melanic form of the moth is a dominant not a recessive form, as made clear by Haldane in the opening sentence of his paragraph: 'The dominant melanic form doubledayaria of the peppered moth ''Amphidasys betularia ... '''

See Haldane JBS. A mathematical theory of natural and artificial selection. Trans Cambridge Philos Soc. 1924;23:19–41. A PDF of a photocopy of the paper may be downloaded from http://www.blackwellpublishing.com/ridley/classictexts/haldane1.asp 121.222.165.11 (talk) 16:18, 10 October 2015 (UTC)


 * I have tried to make corrections. Chhandama (talk) 06:04, 21 July 2016 (UTC)