14 Peppered moth

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In many schoolbooks, the peppered moth is cited as a prime example of observed evolution. There are two forms, one with lighter markings, and the other with darker ones. Due to air pollution during the Industrial Revolution, the white lichens on the bark of trees died off, and the trees were darkened. At that time, the dark moths proliferated faster than the light ones. This is supposed to have happened because the light moths could more easily be seen against the dark tree trunks by the birds that prey upon them. However, this process cannot even be termed micro evolution. It is simply a case of decrease/increase of existing populations.

After it had been assumed that, in the case of the peppered moth, one had found a real observable example of evolution, detailed field studies were carried out. And what did they prove?

Gray Peppered Moth (Biston betularia)   Black Peppered Moth (Biston betularia)

The peppered moth (Biston betularia)

Peppered moths hardly ever settle on tree trunks. In addition, the light form had already started to increase its numbers again, before the lichens had regenerated. Finally, it could even be demonstrated that these moths do not even tend to choose backgrounds matching their own colour.

Evolutionary development:

As far as alleged evolutionary development is concerned, only a shift of the allele frequency and not even the emergence of a new sub-species could be observed. This process can not even be tagged as micro evolution. Note also that the light forms have the dark brown pigment melanin, which is responsible for the colouring. Between the light and dark forms there is only a variation in the synthesis and distribution of melanin.


Should there be any connection whatsoever between pollution and the frequency of dark and light moths?  If so, then it is much more complicated than previously supposed, and so far, not understood (1). The fact that such an example should still be found in modern school textbooks (2) (3) clearly demonstrates how non-critically the theory of evolution in general is accepted.

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(1) Junker und Scherer, Evolution, ein kritisches Lehrbuch, (Weyel, 2006): page 71.
(2) Helmut Schneider, Natura, Biologie für Gymnasien, Band 2, Lehrerband, Part B, 7. to 10. Schuljahr, Ernst Klett Verlag (2006), page 270.
(3) Horst Bayrhuber, Linder Biologie, Lehrbuch für die Oberstufe, 21. Auflage, Schroedel Verlag, Hannover, page 388.

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