Has Darwinism Been Rejected?

 
A number of misconceptions about evolution are described on the website Understanding Evolution for Teachers. One of them is Misconception: “Most biologists have rejected ‘Darwinism’ (i.e., no longer really agree with the ideas put forth by Darwin and Wallace).

Response: Darwin’s idea that evolution generally proceeds at a slow, deliberate pace has been modified to include the idea that evolution can proceed at a relatively rapid pace under some circumstances. In this sense, “Darwinism” is continually being modified. Modification of theories to make them more representative of how things work is the role of scientists and of science itself.

Thus far, however, there have been no credible challenges to the basic Darwinian principles that evolution proceeds primarily by the mechanism of natural selection acting upon variation in populations and that different species share common ancestors. Scientists have not rejected Darwin’s natural selection, but have improved and expanded it as more information has become available. For example, we now know (although Darwin did not) that genetic mutations are the source of variation acted on by natural selection, but we haven’t rejected Darwin’s idea of natural selection—we’ve just added to it.

Here's how I would re-word the first sentence of the second paragraph.

We now know that natural selection is just one of several mechanisms of evolution. One of the others is random genetic drift where variants can become established in a species purely by chance. There is clear evidence that variants that are neither harmful or beneficial can contribute to evolution and, in fact, the evidence suggests strongly that this is the most common form of evolution. However, there have been no credible challenges to the basic Darwinian principles that adaptive evolution proceeds exclusively by the mechanism of natural selection acting upon variation in populations and that different species share common ancestors.

I realize that my version is more complicated but it is also more accurate. This is a case where over-simplification comes at the expense of accuracy and I don't think the spin framing version is worth the sacrifice. There's nothing wrong with informing the general public (and teachers) that Darwinism remains true even though modern evolutionary theory covers much more than just Darwin's central ideas.

Ironically, the Understanding Evolution website has a good description of Genetic Drift, which they describe as "one of the basic mechanisms of evolution." I don't know why don't mention these other mechanisms on the page where they discuss Darwinism.

Now, look at the first paragraph of the website version. I think they're referring to punctuated equilibria. In this case, the extra complication isn't worthwhile because it doesn't really represent a significant change from Darwin's idea of evolution by natural selection. As a matter of fact, the description is downright misleading. The key concept in punctuated equilibria is that evolutionary change is associated with speciation by cladogenesis and the idea that evolution can occur rapidly isn't all that significant.

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