Friday, November 25, 2016

Herding Hemingway's Cats: the perfect primer in genetics for a novice and a fun read for an expert

Herding Hemingway's Cats: Understanding How Our Genes Work has been on my reading list for a few months. When I saw the author Kat Arney tweet that the Kindle price was only $1.99, I took advantage of the price drop and downloaded it right away. I was glad I did, but I do feel a little guilty that I didn't pay full price because it really would have been worth it!

I have reviewed many books on the subject of genetics (I  particularly enjoyed The Violinist's Thumb, Junk DNA, and Inheritance). Nonetheless, I found Hemingway's Cats to have a refreshing take on some well-covered topics; of course, it also taught me some new things and discussed the most recent research. Thus, I recommend this book as an excellent introduction to genetics because it would be suitable for people with little knowledge of genetics; it would also be great for someone who knows the field, but wants to expand or refresh their knowledge.

It seems that one requirement for a book about genetics is an extended analogy for the genome. Sometimes these are clever and useful, but run their course rather quickly (e.g., Matt Ridley's Genome talks about the genome as a book with 23 chapters/chromosomes). Here, Arney makes the occasional comparison between the genome and a set of recipe books. The collection contains thousands of recipes for cake, soups, and casseroles. In her analogy, the librarian never lets the recipes out of her sight, so you have to copy the recipe in the library (the nucleus) and then export the recipe to make it in your kitchen. Sometimes, you need lots of one thinglike a large batch of cupcakes for a bake sale, but other times you just make a single serving. Arney revisits this analogy over the course of the book and it always seems to fit perfectly and it doesn't get overused.

At the start of the Human Genome Project, a  betting pool began among the scientific community to guess the number of proteinencoding genes in the complete human genome (the winner was Lee Rowen, who bet on 25,947, the actual number was 24, 847). Of course, the amount of our genome that is actually of use and the reason humans have so much extra DNA is still a matter of debate. Humans (owing perhaps to our inflated sense of self) figured that the size of the genome would correlate with the complexity of the organism. This turned out to be false for example, "water fleas the size of a grain of rice have 30,000 genes." One hypothesis to explain all that extra DNA is that some of it protects the important parts of our genomes from mutationsthe biological equivalent of bubble wrap. Here, she makes some great comparisons with moving house, making cookies, and television programming. This is a strength throughout the book, which is peppered with fun and useful analogies that help clarify the scientific concepts.  

Arney also hits new and hot topics, like epigenetics/epigenomics, imprinting, CRISPR, and the ever-expanding list of RNAs. In addition, she covers some of the "wow science" one would expect from a popular science book. She describes why the eponymous polydactyl cats have extra toes (mis-regulation of the Sonic Hedgehog gene) and writes about the newest large-scale genome sequencing project (The 100,000 Genomes Project), which aims to sequence the exomes from cancer patients and children with rare diseases and to expand the geographical representation of genomes sequenced thus far. She also speculates on what the future of genetics might be, in particular she focuses on the next dimension of genome sequencing: time. By sequencing the genome of the same individual over time, in combination with the very specific data that can now easily be collected by a smart watch, we might be able to understand how the genome changes as we age and in the context of our lifestyle. It is an exciting time in the field of genetics and molecular biology, and we are particularly lucky to have a writer like Kat Arney to help us understand all the cool things that are happening.

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