How the Peppered Moth Backfired

The Poster Child Became the Rebuttal

It has been called one of the best examples of evolution observed in the wild—light colored peppered moths (Biston betularia) became dark colored in response to 19th century industrial pollution darkening the birch trees in their environment. Evolving a darker color helped camouflage the moths, and keep them hidden from predatory birds. And more recently, air pollution reductions lightened the environment and with it, the moths also began to revert to their lighter color. Proof of evolution, case closed, right? From popular presentations and museum exhibits, to textbooks and scientific papers, evolutionists have relentlessly pounded home the peppered moth as an undeniable confirmation of Darwin’s theory in action. There’s only one problem: All of this ignores the science.

There are two main problems with peppered moths story. First, changing colors is hardly a pathway leading to the kinds of massive biological change evolution requires. It is not as though a change in the peppered moth coloration is any kind of evidence for how the moths evolved, or how any other species, for that matter, could have evolved.

In fact changing the color of a moth not only fails to show how species could evolve, it also fails to show how any biological design could evolve. The peppered moth case doesn’t show how metabolism, the central nervous system, bones, red blood cells, or any other biological wonder could have arisen by evolution’s random mutations coupled with natural selection.

The moths were already there. Their wings were already there. Different colors were already there. The changing of color in moth populations, while certainly a good thing for the moths, is hardly an example of evolution.

Second, research strongly suggests that the cause of the darkening, at the molecular level, is an enormous genetic insertion. In other words, rather than a nucleotide, in a gene, mutating to one of the other three nucleotides, as you learned in your high school biology class, instead what has been found is an insertion of a stretch of more than 20,000 nucleotides. That long inserted segment consists of a shorter segment (about 9,000 nucleotides) repeated about two and one-third times.

Also, the insertion point is not in a DNA coding sequence, but in an intervening region (intron), which have been considered to be “junk DNA” in the past.

This observed mutation (the insertion of a long sequence of DNA into an intron), is much more complicated than a single point mutation. First, there is no change in the gene’s protein product. The mutating of the protein sequence was the whole idea behind evolution: DNA mutations which lead to changes in a protein can lead to a phenotype change with fitness improvement, and there would be subject to natural selection.

That is not what we are seeing in the much celebrated peppered moth example. The DNA mutation is much more complicated (~20,000 nucleotides inserted), and the fact it was inserted into an intron suggests that additional molecular and cellular mechanisms are required for the coloration change to occur.

None of this fits evolutionary theory.

For example, evolutionary theory requires that the needed random DNA mutational change is reasonably likely to occur. Given the moth’s effective population size, the moth’s generation time period, and the complexity of the mutation, the needed mutation is not likely to occur. Evolution would have to be inserting segments of DNA with (i) different sequences, at (ii) different locations, within the moth genome. This is an enormous space of mutational possibilities to search through.

It doesn’t add up. Evolution does not have the resources in terms of time and effective population size to come anywhere close to searching this astronomical mutational space. It’s not going to happen.

A much more likely explanation, and one that has been found to be true in so many other cases of adaptation (in spite of evolutionary pushback), is that the peppered moth coloration change was directed. The environmental change and challenge somehow caused the peppered moth to modify its color. This suggests there are preprogrammed, directed adaptation mechanisms, already in place that are ready to respond to future, potential, environmental changes, which might never occur.

Far from an evidence for evolution, this is evidence against evolution.

So there are at least two major problems with what is celebrated as a key evidence for evolution in action. First, it comes nowhere close to the type of change evolution needs, and the details of the change demonstrate that it is not evolutionary to begin with.