Discussion Question

Evolution by natural selection is a process that has shaped species populations since the beginning of life on Earth. Examples can be seen not only in the fossil record, but actively observed in populations of living organisms that have lifespans much shorter than larger animals. One species cited by evolutionary biologists as a textbook example of observable evolution in progress is Biston betularia, or known by its common name, the peppered moth.

For many years, the peppered moth was an iconic organism that was a straightforward example of evolution by natural selection, and was also easy to understand: The moths have two prevalent colors: Light and dark. Before the industrial revolution in England, the light-colored moths were the most common color, as they were well-camouflaged on the light-colored bark of the trees in which they rested. However, as soot pollution grew in the air from industrialization, it deposited on the trunks of trees near the urban areas, and the number of light-colored moths plummeted as birds could easily see their lighter silhouette against the now dark-colored bark. Contrarily, the dark-colored moths, which were rare in the overall moth population prior to the growth of industry, blossomed in numbers as they were much harder to see on tree bark that was blackened by soot.

However, as scientists recently focused closer on the peppered moth studies from the 1950s, a few questions were voiced about the methods used by the scientist who originally performed them. These questions were taken out of context by groups of individuals outside of evolutionary biology who were intent on calling into question the scientific premise behind evolution by natural selection.

Read:

In the Hunt Library, download and read the essay The Moths of War by Jaap de Roode, from the December 8, 2007 issue ofNew Scientist (this essay is also titled "Reclaiming the peppered moth", in the ScienceDirect database).

Post:

Post a review of this article and the controversy surrounding the peppered moth studies. Identify which statements that scientists made that could have been misconstrued by non-scientists. Were the statements that scientists made inaccurate? How were they taken out of context? What happened to the reputation of the original scientist who did the peppered moth experiments? Were the original experiments ever truly inaccurate? Point out which arguments and which declarations were based on negative critical thinking habits-of-mind, and which ones seemed more positive. Discuss among your peers how the non-scientific community used the statements of scientists, and whether they were using critical thinking skills in their application of them. How did other scientists react to the allegations against the peppered moth experiments? Did they simply concede that something was wrong and leave it at that? Based on your previous studies about the scientific method in Module 1, consider the efforts that scientists must go to in order to review older science for continued credibility, and what they must do if previously understood science is called into question from outside the scientific community. Do they immediately throw away the old science and start fresh? Why or why not?

Respond:

Respond to the posts of at least 2 of your fellow classmates in a thoughtful and courteous manner, and stay objective and open-minded with your point-of-view. You are welcome to bring your own opinions into this discussion, but they must be viewed through the lens of science, will be graded on how you utilize Critical Thinking Habits-of-Mind in your dialog.