Junk DNA and Genetics Textbooks

 
The latest issue of The GSA Reporter, published by the Genetics Society of America, is just out and they have an article on The Ins and Outs of Textbook Authorship. Here's something I agree with.

Anthony Griffiths (University of British Columbia, Vancouver) places more emphasis on core principles than on specific applications: “The goal is to show how genetic inference is made ... hence overall the emphasis is more on process than the discoveries.”

That's right. A textbook should emphasize concepts and principles and not facts. The goal is to show students how all of the knowledge we have fits into a coherent picture of the subject. Genetics, like all sciences, is based on models that represent the consensus view of the scientists in the field. It's important for students to see that these models are internally consistent and compatible with biology and biochemistry and all other sciences. It's important that students realize that there may be some controversy in the discipline but that they need to learn how to sort it out.

The next paragraph says, ...

[Scott] Hawley also places a heavy emphasis on core topics, because he “factor[s] in heavily the concept that so-called facts can be pretty ephemeral in science.” As Hawley explains, “Many of the ‘facts’ I was taught in college are either irrelevant now or wrong. For example, I heard many lectures as an undergrad asserting that a huge part of the genome was useless ‘junk’. We no longer look at things that way.”

I'm looking forward to seeing the next edition of The Human Genome by Julia Richards and Scott Hawley. It will be interesting to see what principles and concepts they advance to explain the absence of junk in our genome.

One of the things textbook authors have to careful of is discarding solid, well-established, models (like junk DNA) based on the results of a few modern experiments. Yes, it's true that new discoveries often overthrow old concepts, but it also true that when new "facts" disagree with established models it's usually the new facts that turn out to be wrong. The idea that theories are frequently overthrown by "nasty little facts" is a myth.

Rejecting the concept of junk DNA has consequences that will be difficult to handle in the next edition. It means re-writing the sections on the C-value Paradox, transposons (especially defective transposons), selfish DNA, pseudogenes, and genetic load. Also, the explanation for why this DNA is functional is going to have serious ramifications for other topics. I can't imagine how they'll put together a coherent picture of modern genetics if they reject junk DNA.

If you're looking for a good genetics textbook then here's my advice. Buy the one that supports the idea of copious amounts of junk in our genome and explains why it has to be junk. Ignore any textbook that rejects the notion of junk DNA—it will probably have other things wrong as well.

---

Thanks to a friend who alerted me to the article in The GSA Reporter.