Also available in the Bloomsbury Sigma series: Sex on Earth by Jules Howard p53 – The Gene that Cracked the Cancer Code by Sue Armstrong Atoms Under the Floorboards by Chris Woodford Spirals in Time by Helen Scales Chilled by Tom Jackson A is for Arsenic by Kathryn Harkup Breaking the Chains of Gravity by Amy Shira Teitel Suspicious Minds by Rob Brotherton 9781472910042_Herding Hemingway's_1stpass.indb 2 9/16/2015 6:57:20 PM HERDING HEMINGWAY ’ S CATS UNDERSTANDING HOW OUR GENES WORK Kat Arney 9781472910042_Herding Hemingway's_1stpass.indb 3 9/16/2015 6:57:20 PM Bloomsbury Sigma An imprint of Bloomsbury Publishing Plc 50 Bedford Square 1385 Broadway London New York WC1B 3DP NY 10018 UK USA www.bloomsbury.com BLOOMSBURY and the Diana logo are trademarks of Bloomsbury Publishing Plc First published 2016 Copyright © Kat Arney, 2016 Kat Arney has asserted her right under the Copyright, Designs and Patents Act, 1988, to be identifi ed as Author of this work. All rights reserved. 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Here you will fi nd extracts, author interviews, details of forthcoming events and the option to sign up for our newsletters 9781472910042_Herding Hemingway's_1stpass.indb 4 9/16/2015 6:57:20 PM To mum and dad, with much love Thanks for the nature and the nurture 9781472910042_Herding Hemingway's_1stpass.indb 5 9/16/2015 6:57:20 PM Contents Introduction: It ’ s All About that Base 9 Chapter 1 : It ’ s Not What You ’ ve Got, it ’ s What You Do With it that Counts 15 Chapter 2 : Taking Out the Garbage 25 Chapter 3 : A Bit of Dogma 37 Chapter 4 : Throwing the Switch 47 Chapter 5 : The Secret ’ s in the Blend 53 Chapter 6 : Cat s w ith Thu mbs 63 Chapter 7 : Fish w ith H ips 73 Chapter 8 : Mice and Men and Mole Rats, Oh My! 81 Chapter 9 : Pa r t y Tow n 91 Chapter 10 : Pi mp My Genome 101 Chapter 11 : Cut and Paste 119 Chapter 12 : Nat u re ’ s Red Pen 133 Chapter 13 : Ever Increasing Circles 143 Chapter 14 : Silence of the Genes 151 Chapter 15 : Night of the Living Dead 165 Chapter 16 : On the Hop 173 Chapter 17 : Opening a Can of Wobbly Worms 183 Chapter 18 : Ever yone ’ s a Little Bit Mutant 195 Chapter 19 : Opening the Black Box 207 Chapter 20 : Blame the Parents 221 9781472910042_Herding Hemingway's_1stpass.indb 7 9/16/2015 6:57:20 PM 8 HERDING HEMINGWAY’S CATS Chapter 21 : Meet the Mickey Mouse Mice 235 Chapter 22 : In Search of the Twenty-fi rst Century Gene 249 Glossary 261 References 263 I ’ d Like to Thank … 280 Index 283 9781472910042_Herding Hemingway's_1stpass.indb 8 9/16/2015 6:57:20 PM INTRODUCTION It ’ s All About that Base t all started with a photo of a cat. I was hiding at the back Iof a scientifi c conference at the Royal Society in London when a cuddly looking cat with unusually big feet caught my eye. ‘ This is a Hemingway cat,’ said the lecturer, pointing at the animal on the large screen behind him. ‘ They have six toes – they ’ re polydactyl. Ernest Hemingway was said to be fond of them, and they still live on his estate in Florida today. And here … ’ he poked at the computer, changing the slide to one covered with photos of misshapen human hands, ‘ … are polydactyl children with extra digits. It ’s the same genetic mistake that causes them. ’ Looking at a six-toed cat or six-fi ngered human, a natural assumption might be that it ’ s due to a fault in a gene. But it ’ s not. In fact the cause lies in a faulty region of DNA that acts as a control switch, normally turning a gene on at the right time in the right place to direct the formation of fi ngers and toes as a baby or kitten grows in the womb. Not only that, but the switch is miles away (in molecular terms) from the gene it acts upon. Learning about the Hemingway cats and their broken switches got me thinking about my own under- standing of how genes work, and how I explain it to the public through my work as a science writer and broadcaster. My fi rst real brush with modern genetics came while I was at secondary school, courtesy of our formidable deputy headmaster Mr Myers. As well as stalking the school corridors with a steely glare of stern disapproval, doling out detentions seemingly at random, he also doubled as a biology teacher. One day it was his turn to preside over the regular school assembly. We dutifully trooped into the main hall to sit 9781472910042_Herding Hemingway's_1stpass.indb 9 9/16/2015 6:57:20 PM 10 HERDING HEMINGWAY’S CATS cross-legged on the fl oor, doing our best to avoid his eye. He took to the stage, black academic gown fl owing out behind him like a cape, clasping in his hand what looked like a magazine but must have been a scientifi c 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 fi shed 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 in seemingly endless permutations. ‘ It’ s like the phone book! All these letters. Letters, letters, letters. ’ A pause for breath. ‘ THIS IS BIOLOGY NOWADAYS! ’ While Mr Myers may have believed that ACTG was a four-letter word, the language of genes has made its way into common parlance over recent years. Genes are the things in your DNA that make your eyes blue, your belly bulge or your hair curl. The newspapers tell us that they control our risk of cancer, heart disease, alcoholism, Alzheimer’ s and more. A thousand dollars will buy you your very own genomic readout, sequenced in a matter of days and neatly stored on a USB stick. Genetic knowledge has the power to save us – there are drugs targeting the products of faulty genes in tumours, and recent advances in gene therapy that let the blind see. And we can trace the march of genes writ large in the seemingly endless variations of life on the face of our planet – evolution is just genetics plus time, after all. Today we merrily talk about all sorts of things being ‘ in our genes’ , from a talent for singing to a life-threatening cancer. My mother is obsessed with family history, believing that almost every aspect of mine and my sisters’ characters can be traced back to one or other of my long-dead ancestors, be they Baptist preachers or depressive alcoholics.* Science writers enthusiastically describe the genome – the sum total of an organism’ s DNA – as the blueprint of life, akin to a computer program or architect’ s plan. The double helix has become a cultural icon, not to mention lazy advertising *Turns out I got both. THANKS, MUM. 9781472910042_Herding Hemingway's_1stpass.indb 10 9/16/2015 6:57:21 PM IT’S ALL ABOUT THAT BASE 11 shorthand for ‘ Ooh, science! ’ But while the language of genetics has infi ltrated the public consciousness, a genuine understanding of what our genes are and what they do has not. Most biology textbooks defi ne genes as particular strings of DNA ‘ letters ’ – chemicals known as bases – and there are four of them in common use in all living things: A, C, T and G, short for adenine, cytosine, thymine and guanine. The particular order of the letters encodes instructions telling the cells in your body to make various molecules, in the same way that diff erent recipes encode the directions for making cakes, pies or stews. Unfortunately, it ’ s not as simple as viewing our genome as a biological Mrs Beeton. As technology develops and scien- tists discover more about the secrets within our cells, the picture has begun to get very murky indeed. More than two metres (6.6 feet) of DNA is packed into almost every cell of your body, crammed with thousands of genes that need to be turned on and off at the right time and in the right place. Rather than a neatly bound set of recipes, the genome as we understand it today is a dynamic, writhing library, buzzing with biological readers and writers.