Kettlewell's experiment
The experiment found that birds selectively prey on peppered moths depending on their body colour in relation to their environmental background.
The study concluded that "industrial melanism in moths is the most striking evolutionary phenomenon ever actually witnessed in any organism, animal or plant.
"[3] It is now regarded as the classic demonstration of Charles Darwin's natural selection in action and one of the most beautiful experiments in evolutionary biology.
By the end of the century, it was recorded that the black moth, the carbonaria type, outnumbered (90% in some regions) the natural white ones, named typica.
[12] He tested his scoring method in the woodlands near Birmingham by releasing 651 peppered moths (consisting of typica, carbonaria and insularia), and then at an aviary at the Research Station in Madingley in Cambridge.
He caught all three types of peppered moth and marked them underneath their wings with cellulose paint, so that he would be able to identify them later from non-experimental individuals after recapture.
In 1954 he surveyed several woodlands including Devon and Cornwall, but found them unsuitable because of presence of some carbonaria forms, which indicated unclean environment.
Based on his experiments between 1965 and 1969, he concluded that it was not possible to reproduce Kettlewell's results, and said that birds showed no preference on moth on either black or white tree trunks.
[18] When the biologist Jerry Coyne reviewed this book in Nature, he stated that the most serious problem was that only two peppered moths had been found on tree trunks.
Coyne compared his reaction to "the dismay attending my discovery, at the age of 6, that it was my father and not Santa who brought the presents on Christmas Eve".
[19] Contrary to this review, Majerus had stressed that the basic findings from that work were correct, and that differential bird predation of polluted environment "is the primary influence of the evolution of melanism in the peppered moth".
[24] The review was subsequently picked up by the journalist Robert Matthews, who wrote an article for The Sunday Telegraph, 14 March 1999, claiming that "the rise and fall of the peppered moth, is based on a series of scientific blunders.
Experiments using the moth in the Fifties and long believed to prove the truth of natural selection are now thought to be worthless, having been designed to come up with the 'right' answer."
[23] David W. Rudge, after critical analyses of Kettlewell' works, declared that "none of Hooper's arguments is found to withstand careful scrutiny",[34] and that all "these charges are baseless and stem from a fundamental misunderstanding of the nature of science as a process.
"[36] This led Frack to exchange with intelligent design proponent Jonathan Wells, who conceded that Majerus listed six moths on exposed tree trunks (out of 47), but argued that this was "an insignificant proportion".
"[39] The arguments were dismissed by Majerus, Cook and Bruce Grant who describes Wells as distorting the picture by selectively omitting or scrambling references in a way that is dishonest.
[20] Professional photography to illustrate textbooks uses dead insects because of the considerable difficulty in getting good images of both forms of moth in the same shot.
[20] While an experiment did involve the gluing of dead moths to trees, this practice was just one of many different ways used to study different individual elements of the overall hypothesis.
This particular experiment was not meant to exactly reproduce natural conditions but instead was used to assess how the numbers of moths available (their density) affected the foraging practices of birds.
)[42] Coyne and Grant wrote a letter to The Pratt Tribune in which they defended the moth experiments and revealed the misrepresentations by Wells.
