The Epigenetics Revolution

The Epigenetics Revolution: How Modern Biology Is Rewriting Our Understanding of Genetics, Disease, and Inheritance

NESSA CAREY
Copyright Date: 2012
Pages: 352
https://www.jstor.org/stable/10.7312/care16116
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  • Book Info
    The Epigenetics Revolution
    Book Description:

    Epigenetics can potentially revolutionize our understanding of the structure and behavior of biological life on Earth. It explains why mapping an organism's genetic code is not enough to determine how it develops or acts and shows how nurture combines with nature to engineer biological diversity. Surveying the twenty-year history of the field while also highlighting its latest findings and innovations, this volume provides a readily understandable introduction to the foundations of epigenetics.

    Nessa Carey, a leading epigenetics researcher, connects the field's arguments to such diverse phenomena as how ants and queen bees control their colonies; why tortoiseshell cats are always female; why some plants need cold weather before they can flower; and how our bodies age and develop disease. Reaching beyond biology, epigenetics now informs work on drug addiction, the long-term effects of famine, and the physical and psychological consequences of childhood trauma. Carey concludes with a discussion of the future directions for this research and its ability to improve human health and well-being.

    eISBN: 978-0-231-53071-2
    Subjects: Ecology & Evolutionary Biology, Developmental & Cell Biology, Biological Sciences

Table of Contents

  1. Front Matter
    (pp. i-vi)
  2. Table of Contents
    (pp. vii-viii)
  3. Acknowledgements
    (pp. ix-x)
  4. Introduction
    (pp. 1-10)

    Sometimes, when we read about biology, we could be forgiven for thinking that those three letters explain everything. Here, for example, are just a few of the statements made on 26 June 2000, when researchers announced that the human genome had been sequenced¹:

    Today we are learning the language in which God created life.

    US President Bill Clinton

    We now have the possibility of achieving all we ever hoped for from medicine.

    UK Science Minister Lord Sainsbury

    Mapping the human genome has been compared with putting a man on the moon, but I believe it is more than that. This...

  5. Chapter 1 An Ugly Toad and an Elegant Man
    (pp. 11-22)

    Humans are composed of about 50 to 70 trillion cells. That’s right, 50,000,000,000,000 cells. The estimate is a bit vague but that’s hardly surprising. Imagine we somehow could break a person down into all their individual cells and then count those cells, at a rate of one cell every second. Even at the lower estimate it would take us about a million and a half years, and that’s without stopping for coffee or losing count at any stage. These cells form a huge range of tissues, all highly specialised and completely different from one another. Unless something has gone very...

  6. Chapter 2 How We Learned to Roll Uphill
    (pp. 23-41)

    Let’s move on about 40 years from John Gurdon’s work, and a decade on from Dolly. There is so much coverage in the press about cloned mammals that we might think this procedure has become routine and easy. The reality is that it is still highly time-consuming and laborious to create clones by nuclear transfer, and consequently it’s generally a very costly process. Much of the problem lies in the fact that the process relies on manually transferring somatic nuclei into eggs. Unlike the amphibians that John Gurdon worked on, there’s the additional problem that mammals don’t produce very many...

  7. Chapter 3 Life As We Knew It
    (pp. 42-53)

    If we are going to understand epigenetics, we first need to understand a bit about genetics and genes. The basic code for pretty much all independent life on earth, from bacteria to elephants, from Japanese knotweed to humans, is DNA (deoxyribonucleic acid). The phrase ‘DNA’ has become an expression in its own right with increasingly vague meanings. Social commentators may refer to the DNA of a society or of a corporation, by which they mean the real core of values behind an organisation. There’s even been a perfume called after it. The iconic scientific image of the mid-20th century was...

  8. Chapter 4 Life As We Know It Now
    (pp. 54-74)

    So far this book has focused mainly on outcomes, the things that we can observe that tell us that epigenetic events happen. But every biological phenomenon has a physical basis and that’s what this chapter is about. The epigenetic outcomes we’ve described are all a result of variations in expression of genes. The cells of the retina express a different set of genes from the cells in the bladder, for example. But how do the different cell types switch different sets of genes on or off ?

    The specialised cell types in the retina and in the bladder are each...

  9. Chapter 5 Why Aren’t Identical Twins Actually Identical?
    (pp. 75-96)

    Identical twins have been a source of fascination in human cultures for millennia, and this fascination continues right into the present day. Just taking Western European literature as one source, we can find the identical twins Menaechmus and Sosicles in a work of Plautus from around 200 B.C.; the re-working of the same story by Shakespeare in The Comedy of Errors, written around 1590; Tweedledum and Tweedledee in Lewis Carroll’s Through the Looking-Glass, and What Alice Found There written in 1871; right up to the Weasley twins in the Harry Potter novels of J. K. Rowling. There is something inherently...

  10. Chapter 6 The Sins of the Fathers
    (pp. 97-114)

    The Just So stories published by Rudyard Kipling at the very beginning of the 20th century are an imaginative set of tales about origins. Some of the most famous are those about the phenotypes of animals – How the Leopard Got his Spots, The Beginning of the Armadillos, How the Camel Got his Hump. They are written purely as entertaining fantasies but scientifically they hark back to a century earlier and Lamarck’s theory of evolution through the inheritance of acquired characteristics. Kipling’s stories describe how one animal acquired a physical characteristic – the elephant’s long trunk, for example – and the implication is...

  11. Chapter 7 The Generations Game
    (pp. 115-128)

    Sometimes, the best science starts with the simplest of questions. The question may seem so obvious that almost nobody thinks to ask it, let alone answer it. We just don’t challenge things that seem completely self-evident. Yet occasionally, when someone stands up and asks, ‘How does that happen?’, we all realise that a phenomenon that seems too obvious to mention, is actually a complete mystery. This is true of one of the most fundamental aspects of human biology, one we almost never think about.

    When mammals (including humans) reproduce, why does this require a male and a female parent?

    In...

  12. Chapter 8 The Battle of the Sexes
    (pp. 129-151)

    The laboratory stick insect Carausius morosus is a very popular pet. As long as it has a few privet leaves to munch on it will be perfectly content, and after a few months it will begin to lay eggs. In due course, these will hatch into perfect little baby stick insects, looking just like miniature versions of the adults. If one of these baby stick insects is removed as soon as it is born, and kept in a tank on its own, then it too will lay eggs which will hatch into little stick insects in their turn. This is...

  13. Chapter 9 Generation X
    (pp. 152-177)

    At a purely biological, and especially an anatomical level, men and women are different. There are ongoing debates about whether or not certain behaviours, ranging from aggression to spatial processing, have a biological gender bias. But there are certain physical characteristics that are linked unequivocally to gender. One of the most fundamental differences is in the reproductive organs. Women have ovaries, men have testicles. Women have a vagina and a uterus, men have a penis.

    There is a clear biological basis to this, and perhaps unsurprisingly, it’s all down to genes and chromosomes. Humans have 23 pairs of chromosomes in...

  14. Chapter 10 The Message is Not the Medium
    (pp. 178-204)

    One of the most influential books on the philosophy of science is Thomas Kuhn’s The Structure of Scientific Revolutions, published in 1962. One of the claims in Kuhn’s book is that science does not proceed in an orderly, linear and polite fashion, with all new findings viewed in a completely unbiased way. Instead, there is a prevailing theory which dominates a field. When new conflicting data are generated, the theory doesn’t immediately topple. It may get tweaked slightly, but scientists can and often do continue to believe in a theory long after there is sufficient evidence to discount it.

    We...

  15. Chapter 11 Fighting the Enemy Within
    (pp. 205-232)

    There are multiple instances in science of a relatively chance event leading to a wonderful breakthrough. Probably the most famous example is Alexander Fleming’s observation that a particular mould, that had drifted by chance onto an experimental Petri dish, was able to kill the bacteria growing there. It was this random event that led to the discovery of penicillin and the development of the whole field of antibiotics. Millions of lives have been saved as a result of this apparently chance discovery.

    Alexander Fleming won the Nobel Prize for Physiology or Medicine in 1945, along with Ernst Chain and Howard...

  16. Chapter 12 All in the Mind
    (pp. 233-261)

    One of the most noticeable publishing trends of the last ten years has been the rise and rise of the ‘misery memoir’. In this genre, the authors recount the tough times of their childhood and how they have risen above them to be successful and fulfilled individuals. The genre can be sub-divided into two categories. The first is the poor-but-happy tale, the ‘we had nothing but we had love’ story. The second, which may or may not also include poverty, tends to be much more disturbing. It focuses on harrowing tales of childhood neglect and childhood abuse, and some of...

  17. Chapter 13 The Downhill Slope
    (pp. 262-281)

    Time moves forward, we age. It’s inevitable. And as we get older, our bodies change. Once we’re past our mid-thirties most of us would agree that it gets harder and harder to sustain the same level of physical performance. It doesn’t matter if it’s how fast we can run, how far we can cycle before needing to stop for a break, or how quickly we recover from a big night out. The older we get, the harder everything seems to become. We develop new aches and pains, and succumb more easily to annoying little infections.

    Ageing is something we are...

  18. Chapter 14 Long Live the Queen
    (pp. 282-292)

    The effects of nutrition on the health and lifespan of mammals are pretty dramatic. As we saw in the previous chapter, prolonged calorie restriction can extend lifespan by as much as one-third in mice¹. We also saw in Chapter 6 that our own health and longevity can be affected by the ways our parents and grandparents ate. These are quite startling findings but nature has provided us with a much more dramatic example of the impact of nutrition on lifespan. Imagine, if you can, a dietary regime that means a select few in a species have a lifespan that is...

  19. Chapter 15 The Green Revolution
    (pp. 293-303)

    Probably all of us are familiar with the guessing game ‘animal, vegetable or mineral’. The implicit assumption in the name of this game is that plants and animals are completely different from one another. True, they are both living organisms, but that’s where we feel the similarity ends. We may be able to get on board with the idea that somewhere back in the murky evolutionary past, humans and microscopic worms have a shared ancestor. But how often do we ever wonder about the biological heritage we share with plants? When do we ever think of carnations as our cousins?...

  20. Chapter 16 The Ways Ahead
    (pp. 304-312)

    One of the most exciting things about epigenetics is the fact that in some ways it’s very accessible to non-specialists. We can’t all have access to the latest experimental techniques, so not all of us will unravel the chromatin changes that underlie epigenetic events. But all of us can examine the world around us and make predictions. All we need to do is look to see if a phenomenon meets the two most essential criteria in epigenetics. By doing this, we can view the natural world, including humans, in a completely new light. These two criteria are the ones we...

  21. Notes
    (pp. 313-324)
  22. Glossary
    (pp. 325-328)
  23. Index
    (pp. 329-342)