This is part of my review of The Myth of Junk DNA. For a list of other postings on this topic see the link to Genomes & Junk DNA in the "theme box" below or in the sidebar under "Themes."
Chapter 2 is Junk DNA: The Last Icon of Evolution? It's mostly an explanation of how the concept of junk DNA fits into evolution. According to Wells, Darwin's theory of evolution by natural selection explains how living things descend with modification from a common ancestor. (Recall that Wells rejects common ancestry.) Wells explains that Darwin's original idea has been extended with the discovery of DNA. He describes "neo-Darwinism" like this ...
According to neo-Darwinism, traits are passed on by genes that reside on microscopic thread-like structures in the cells called chromosomes, and new traits arise from accidental genetic mutations.In order to clear up any confusion, Wells tells us that, "... I will use "Darwinism" in the rest of the book to mean both Darwin's theory and neo-Darwinism" (p. 19). This is important since it's clear that he's talking about the theory of natural selection when he talks about Darwinism or neo-Darwinism.
Wells describes how Ohno coined the term "junk" DNA in 1972 then quotes Richard Dawkins as a supporter of junk. He states his belief that a couple of papers on selfish DNA in 1980 were taken as evidence of junk. He concludes that ...
... some biologists were skeptical of the notion of "junk DNA" from the very beginning—though most accepted it.Wells fails to distinguish between those biologists who recognize the existence of junk DNA (e.g. pseudogenes) and those who thought that most of our genome is junk. I still believe that only a minority of biologists think that most our genome is junk. I also think that many biologists make a distinction between "junk" and "selfish." I know I do. In my mind "selfish" DNA, such as active transposons or endogenous retroviruses, isn't junk.
Next comes a couple of pages under the subheading "Using Junk DNA as Evidence for Darwinism and Against Intelligent Design." The usual suspects are mentioned. He quotes Ken Miller, Douglas Futuyma, Michael Shermer, Francis Collins, Phil Kitcher, Jerry Coyne, and John Avise. Although their emphasis varies, they all make the point that the presence of junk DNA in our genome is not consistent with intelligent design. It is, however, consistent with evolution (but not natural selection).
& Junk DNAIt's important to note that biologists don't, with rare exceptions, claim that the presence of junk DNA is evidence for Darwinism or evolution. It's consistent with our understanding of modern evolutionary theory but compact genomes with no junk would also be consistent with evolution, especially evolution by natural selection.
Most of these writers are pointing out how difficult it is for Intelligent Design Creationists to make their case in light of massive amounts of junk in our genome. They are mostly arguing against design and not for evolution.1 This point will come up again in Chapter 10.
Wells concludes with ...
The arguments by Dawkins, Miller, Shermer, Collins, Kitcher, Coyne and Avise rest on the assumption that most non-coding DNA is junk, without any significant biological function. Yet a virtual flood of recent evidence shows that they are mistaken: Much of the DNA they claim to be "junk" actually performs important functions in living cells.The stage is set. In the rest of the book, Jonathan Wells will try and convince us that most of the DNA in our genome is not junk. Pay attention 'cause it's important to keep the main focus of the dispute in center stage. What the scientists are saying is that there's a lot of junk in our genome and, in order to blunt that attack on design, Wells has to show that there's not very much junk DNA (perhaps none). It won't be sufficient to show that a few percent here and there aren't junk. Any amount of junk DNA is a threat to the basic concept of intelligent design. That's why the IDiots are so worried.
1. I often make the same argument against adaptationists. Some of them see design by natural selection as the dominant feature of evolution but that's not what our genome tells us. There's no illusion of apparent design in our genome sequence.