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Friday, December 14, 2007

Revenge of the Peppered Moth

Seven years ago, the creationists launched a attack on the peppered moth. Jonathan Wells tried hard to prove that this well-known example of natural selection was a fraud.

In recent years, this attack has been blunted by first showing that most of what the creationists said was a misrepresentation of the truth (surprise!) and then showing that the actual problems with the original experiments of Kettlewell did not invalidate the conclusion.

More recently, Michael Majerus has repeated the original work in a seven year study of birds preying on peppered moths. This has resulted in an example of natural selection that is more solid than ever before. Naturally, given that creationists are mostly IDiots, there are some who still cling to the myth that peppered moths don't undergo selection [Peppered Moths and the Confused IDiots].

This week's issue of New Scientist has a four page article on the peppered moth [Reclaiming the peppered moth for science]. The article presents an excellent summary of the issue and it's resolution.

More importantly, the article is accompanied by an editorial that I'm going to reproduce here in full. We need more of this kind of blunt talk in the popular science magazines.

IN 2000, a popular school textbook called Biology reluctantly dropped its prime example of evolution in action - industrial melanism in the peppered moth. Nothing in evolutionary biology had forced the change. The decision was entirely political, made in response to creationist attacks.

The loss of the peppered moth was a blow to science education in the US, as it is one of the easiest to understand examples of evolution by natural selection. So it is heartening to hear that biologists are fighting back ("Reclaiming the peppered moth"). Thanks to their efforts, evidence that the moth is an example of evolution in action is more robust than ever.

This tawdry tale reveals much of what is good about science - and rotten about creationism. Creationists went gunning for the moth after a scientific disagreement over the fine detail of a seminal experiment done in the 1950s. They used the debate to portray the science behind industrial melanism as hopelessly flawed, if not fraudulent.

In response, one scientist patiently redid the experiment - it took him seven years. It is hard to think of another system of thought that is so stringently self-critical and self-correcting. In science, everything is provisional. There are no preordained answers and fresh ideas are always welcome, so long as their proponents are happy for them to be tested.

That is not how creationists work. They already know the answer. They seek only evidence that confirms their conclusion, and distort or ignore the rest. Such an unreasoned approach is worthless. Creationists will keep trying to undermine the theory of evolution. All science can do is continue, with dignity, to stick to its guns. As with the peppered moth, the best testable explanation will win out.

[Photo Credit: The photographs are from bill.srnr.arizona. The original source is unknown.]


Acleron said...

It wasn't just the creationists who criticised, Jerry Coyne also had doubts as it wasn't shown that moths with different colour schemes were selected for by birds when on the wrong colour tree.
Commenting on the new results by Majerus, Coyne welcomed the moth story back into the textbooks. In stark contrast, on a creationist forum somebody commented that even if the new data was true, it wouldn't change his mind about evolution.

Anonymous said...

I'm glad the Peppered moth has made a come-back!!!

This is another example of why a creator (=a god) is an irrelevant theory for how everything came in to being. It's not falsifiable, and there is no evidence as to how the mechanisms which bring about the changes actually work.

Creationism is on the run at last.