For more than 10 years, scientists have known nearly every letter in the human genetic instruction book. But perhaps more interesting than those letters are the doodles in the margins and the highlighted passages — chemical modifications to DNA and its associated proteins known as epigenetic marks. These scribbles may actually control how genes function, and thus how a person looks and acts. And these changes are passed along to future generations, like carbon copy overlays in new editions.
Researchers are only beginning to decipher this cryptic language, but already it’s clear that whatever these graffiti have to say is going to be important. Such epigenetic modification may be at the root of many diseases, for example. Epigenetics links external experiences to the molecular machinery inside cells. Francis’ book is intended as a guided tour of this mysterious new landscape.
Each chapter starts with an entertaining or intriguing example of how epigenetics affects human and animal biology and inheritance. It’s not often you find José Canseco, mouse mothers, Dutch famine victims, sea urchins, identical twins and Tasmanian devils all in the same book, but you will here. Francis just manages to save his story from crossing into textbook territory by weaving these examples throughout the chapters.
It’s still early days for the science of epigenetics, and researchers keep discovering layer after layer of epigenetic wallpaper plastered over DNA. Francis hits the highlights here, but stay tuned for more installments in this fascinating new science.
W. W. Norton & Co., 2011, 234 p., $25.95
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