Talk:Peppered moth/Archive 1

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The English moth, Biston betularia, is a frequently cited example of observed evolution. [evolution: a change in the gene pool] In this moth there are two color morphs, light and dark. H. B. D. Kettlewell found that dark moths constituted less than 2% of the population prior to 1848. The frequency of the dark morph increased in the years following. By 1898, the 95% of the moths in Manchester and other highly industrialized areas were of the dark type. Their frequency was less in rural areas. The moth population changed from mostly light colored moths to mostly dark colored moths. The moths' color was primarily determined by a single gene. [gene: a hereditary unit] So, the change in frequency of dark colored moths represented a change in the gene pool. [gene pool: the set all of genes in a population] This change was, by definition, evolution.

The increase in relative abundance of the dark type was due to natural selection. The late eighteen hundreds was the time of England's industrial revolution. Soot from factories darkened the birch trees the moths landed on. Against a sooty background, birds could see the lighter colored moths better and ate more of them. As a result, more dark moths survived until reproductive age and left offspring. The greater number of offspring left by dark moths is what caused their increase in frequency. This is an example of natural selection.

Is the above false, LDC?

It's a little complicated. The original photos from the 1950s were in fact staged, and it is true that peppered moths generally light on leaves, not trunks. On the other hand, more careful measurements taken since the original claim show that the relative population of light and dark moths is tending toward increasing numbers of dark moths, and that these numbers do follow urban/rural boundaries, suggesting that the story might have been one of those real-life-imitates-fraud things. I'm not sure what the best way to report on that is. I generally tend to avoid the story altogether, since it's really not important in the grand scheme of things, and bringing it up only leads to pointless discussions like this. :-) --LDC

A good cite: Interesting. BTW, LDC, I am an evolutionist and it seems to me that comments like "I generally tend to avoid the story altogether" could easily seem weasely to a creationist.

Well, I should clarify that: I don't avoid it in the sense of "ducking" the issue; Ed asked, I answered. What I meant was that I don't bring it up as an example, because the controversy is distracting. When there are so many other good examples, why pick one that just leads to trouble? And thanks for the link, that's a great explanation. I'll try to write up something like that here. --LDC