Book Review: The Epigenetics Revolution - How Modern Biology is Rewriting Our Understanding of Genetics, Disease and Inheritance

In her new book, 'The Epigenetics Revolution', Nessa Carey argues that we are in the midst of the next great upheaval in biological thinking. Epigenetics refers to heritable alterations in the expression of genes, resulting in knock-on effects that direct how a cell will behave and what it will become, and all without making any changes to the DNA sequence itself.

If all our cells contain the same genetic material at the level of the DNA sequence, how then do they acquire such differing characteristics, and how are these retained? In other words, what causes cells to develop into specific types? Why do liver cells produce more liver cells when they divide? What stops neurons from growing in our heart? Much of Carey's book is devoted to answering these questions by drawing on the (relatively) new science of epigenetics.

Simplified, epigenetics involves small chemical changes to the DNA, or closely associated proteins called histones, that result in alterations in the expression of genes. When cells divide, many of these modifications are maintained, allowing information about the status of gene expression to be passed from parent cell to daughter. Importantly, these epigenetic modifications result from environmental perturbations, where 'environment' refers to the internal chemistry of the cell or the signals bombarding the cell from outside, whether from neighbouring cells or the wider world beyond.

Early in the book, Carey describes the molecular mechanisms behind epigenetic phenomena. DNA and histone modifications are rightly afforded much insightful commentary, but the role of non-protein coding RNA molecules is exiled to much later and is not, in my opinion, given sufficient attention.

Though the majority of epigenetic modifications are erased during development of the human embryo, it seems that in some rare cases they can be passed on to the next generation. However, at the moment we ought not read too much into this. There remains little concrete evidence that epigenetic phenomena alone can drive evolutionary adaptations, although there is much vociferous debate in the scientific community regarding the extent of its effects. It is perhaps surprising then to find very little discussion of the role of epigenetics in evolution in Carey's book. This omission is a shame as popular science at its best is a wonderful medium for such debate. For this topic, I recommend 'Evolution in Four Dimensions' by Eva Jablonka and Marion Lamb.

Instead, Carey largely focuses on cell and molecular biology, with topics including stem cells, ageing, psychiatric disorders and cancer. Here, she is expert and engaging. From her lucid prose you can learn how a period of malnutrition during pregnancy can have quantifiable effects on the health status of future generations. You can come to appreciate that the genome inherited from mother is not identical to that inherited from father and that while these two genomes cooperate fabulously to create new life, they are nevertheless locked in an evolutionary battle of the sexes.

More than your average popular science book, there is a commendable depth of explanation and a wealth of scientific terminology to be found here. While the latter may be off-putting to some, Carey's adept use of metaphor provides clarity throughout.

Without being mawkish, the author is explicit in her regard for the principle players in the epigenetics arena, particularly those whose insight and experimental dexterity pioneered the now burgeoning field. We are introduced to the trailblazing work of John Gurdon, whose early work led to the technology used to create Dolly, the famous and arthritic sheep. We are also afforded a flavour of Gurdon as the 'quintessential older English gentleman', adding a human face to scientific discovery.

The philosopher of science Thomas Kuhn once wrote that 'when paradigms change, the world itself changes with them'. What then will be the broader implications of our increasing understanding of epigenetic phenomena and their molecular principles? The science of regenerative medicine and the technology of induced pluripotent stem cells – both discussed in 'The Epigenetics Revolution' – offer tremendous potential for the future treatment of human disease. Carey also discusses so-called 'epigenetic therapies' for cancer that, whilst still in the embryonic phase, may be powerful tools in the future. For now though, much work remains and we must guard strongly against the raising of false hope.

'The Epigenetics Revolution' is, to my knowledge, the first popular science book that tackles in depth the subject of its title. This salient fact is almost reason enough to recommend it. As an active biologist already familiar with many of the concepts, I found the book both interesting and informative. Any reader of science will find much here to enjoy. Carey's achievement is an up-to-date account of an important aspect of modern molecular biology, written with dry humour, peppered with historical anecdotes, sometimes challenging, but always clear and insightful.

Buy Embryology at a Glance from Amazon UK.