Source of book: Borrowed from the library
Yet another impulse pick from the new books shelf at the library. I think I have a problem.
This book is about genetics, which makes it a cousin, if you will, of a previous book on that topic, The Violinist’s Thumb by Sam Kean. (I’m a big Sam Kean fan, so you can find posts about his three pop-science books on this blog.) This book is quite a bit different, however. Kean writes his books by exploring a topic through stories. Each chapter will typically focus on a real life story, and bring the science into the discussion. By contrast, Arney focuses more on the science, both the process of discovery, and the current understanding of how things work. In genetics, there are so many remaining mysteries and controversies that the best she can do in many cases is lay out the different competing hypotheses.
Each chapter focuses on one area of genetics, whether the genes themselves (genes encode recipes for proteins), the control switches that turn genes off and on, or the many other areas of DNA that do different things - or nothing at all.
Probably the thing that was most apparent from this book is that the more we learn about genetics, the more “kludgy” our genetic code appears to be. And by “our” I mean that of all living creatures. Even simple organisms show signs of mutation and junk and unnecessarily complex ways of doing things. It is certainly not how an engineer would do things. But it fits very well with the idea that the genetic code arose through mutation and selection. If something “worked,” it stuck, even if there was a simpler way of doing things. Useless bits could stick around indefinitely, as long as they didn’t kill the organism before reproduction. (As Sam Kean noted, we have a lot of junk in our DNA that was randomly inserted by viruses in our past. It doesn’t harm us, but it generally doesn’t do anything either.)
I won’t even attempt to get into the various topics. There are 22 chapters, each of which addresses a different facet of genetics. Each chapter builds on the last, so picking one out of midstream is unhelpful.
There are a few things that are worth mentioning, though. First, DNA and genetics has become a kind of shorthand for “science.” Anyone can recognize the DNA molecule, and spout off some nonsense about genes. But most of what we “know” in the pop cultural sense is wrong. Particularly, the idea of genes as a neat cookbook for life, or the idea that most diseases are due to a single faulty gene. The whole picture is both far more complex and nuanced, and also less neat and orderly than believed. One thing is true, however. Our understanding of genetics is fairly new, and has grown exponentially over the last few decades. Still, we have a long way to go to understand even fairly basic mechanisms. When we look back on our era from 100 years hence, chances are, our present understanding will be viewed as primitive.
In the introduction, the author recalls her secondary school headmaster (she’s British, so this is the equivalent of high school here in the US) bemoaning “modern” science.
“He took to the stage, black academic gown flowing out behind him like a cape, clasping in his hand what looked like a magazine, but must have been a scientific journal of some kind. Towering in impotent fury from the stage, he shook it at us in disapproval as if it were a piece of pornography fished out from behind a cistern in the boys’ toilets. ‘Look at this!’ he thundered, slapping at a page covered in the letters A, C, T and G, repeated ins seemingly endless permutations. ‘It’s like the phone book! All these letters. Letters, letters, letters.’ A pause for breath. “THIS IS BIOLOGY NOWADAYS!’”
In our own cultural moment where science is broadly dismissed and denigrated, and faked “studies” by discredited hucksters are considered by many to outweigh multiple repeated large scale legitimate studies, this is both amusing and all to prescient.
In the interest of equal time, I’ll note with amusement the line from geneticist Mark Ptashne that scientists often use “complex” when they mean “mysterious.” The tendency to pretend understanding where there is none…
Another bit which stood out on its own was the discussion on genetic switches. While this implies on and off, many serve more like a dimmer, adjusting the activity of a gene. One particular set of switches control the genes for melanin production. In essence, just a few letters in a few switches among billions of DNA bases are responsible for a trait which has been the pretext for millennia of violence, enslavement, genocide, and prejudice.
One final one: even the “simple” genes, the ones that encode proteins, turn out to be neither simple nor straightforward. In fruit flies (which are the most studied animal because of their relatively simple genome, fast generation, and ease of handling), one particular gene codes not one or two proteins, but 38,016 different RNA messages, depending on how it splices. This is both kludgy and innovative. On the one hand, it saves space to reuse one gene. On the other, it looks a bit like using duct tape for everything. It isn’t always pretty, it doesn’t always hold together, it tends to waste energy due to mistakes in transcription, but it is “good enough.” Which is really all evolution needs.
This is a fascinating book, fairly heavy on the science for a pop-sci book, but intriguing. Kat Arney’s background in both science and writing are apparent. Her main gig right now is with the UK Cancer Research Center, where she is responsible for translating science jargon into understandable English for the rest of us. She succeeds in this book. Her obvious grasp of the topic combines with a clear writing style that makes the complex understandable.
One warning, however. This book does assume that the reader has a high school level of biology and genetics. If you don’t already have a basic idea of what DNA, RNA, and proteins are, and how a cell is laid out, you probably should brush up before reading the book, as she does not go back and explain the basics.
I rather enjoyed this book, and recommend it for anyone interested in expanding their knowledge of modern genetics.
The title, by the way, comes from the “Hemingway" cats, genetic mutants that have six toes on a paw. Okay, sort of. My family owned several of them during my teens, so I have some firsthand knowledge. Normal cats have five toes on the front paws, four on the back. The most common Hemingway variant adds a non-functional claw between the “thumb” and first finger of the front paws, sometimes accompanied by a vestigial fifth claw midway up on the back paw. We had some like this. A few will have even more toes. One cat we had was truly unusual (and very rare). He had six toes on each front paw - but they were all connected to bone and evenly spaced. The rear paws were even more unusual, with five equally spaced toes. His paw prints in the snow were unusual. Like the Sasquatch of felines.
Tell me you can resist that...
My kids really like the DNA Cat logo on the book.