The Developing Genome: An Introduction to Behavioral Epigenetics by David S. Moore (review)

For much of the twentieth century, neo-Darwinism and DNA-centric Mendelism have served as the dominant epistemes of modern biology, establishing a rigid notion of inheritance in which the human genome alone determines the passage of phenotypes between generations. Common metaphors of DNA as a “blueprint” or a “set of instructions” have subsequently established a widespread discourse of genetic determinism in which our genes dictate ontogeny and phylogeny alike. Over the past two decades, however, a wellspring of research in epigenetics—a subfield of biology concerned with the interaction of DNA, its associated molecules, and the environment in ways that influence gene expression—has challenged this thinking. In the process it has exploded across the popular and academic imaginations. Indeed, by reconfiguring our basic understanding of evolution, genetics, and the nature-versus-nurture debate, epigenetics intervenes across an array of disciplines, including medicine, philosophy, psychology, and law. While previous monographs on this burgeoning field have covered various aspects of epigenetic research, few have holistically addressed its development and implications with as much style, rigor, and accessibility as David Moore’s latest book. The Developing Genome traverses the cellular mechanisms, landmark studies, and cultural consequences of this Kuhnian-style paradigm shift. While the range of contemporary epigenetic research is vast, Moore, a professor of psychology at Pitzer College and Claremont Graduate University, focuses on the psychological and physiological development of individuals within behavioral epigenetics. This text maintains two key objectives: to introduce readers to a complex new science, and to articulate the ideological concerns it raises. Moore succeeds in this endeavor because he never loses sight of the larger human questions driving interest in epigenetics in the first place. “Epigenetics is important,” he writes, “because of what it says about who we are and how we should live our lives” (p. 65).

The twenty-three chapters of The Developing Genome unfold in four sections. Part 1, “What’s the Big Deal? Getting Up to Speed,” lays out the genealogical and biological foundations of epigenetics, with an emphasis on its cultural import. In chapters 1 and 2 Moore argues that the long-running nature-versus-nurture debates have been ceded to the former in recent decades, with DNA reliably determining (random mutations aside) everything from physiology to personality, a biological discourse akin to predestination. Epigenetics acts as an empirical counter-narrative because it investigates how outside factors like diet or social stressors can regulate gene expression. “The traditional perspective holds that what really matters is the genes you have,” explains Moore, but “given that genetic activity levels change in different circumstances, what really matters is what your DNA is doing” (p. 14; emphasis in original). In chapter 3 Moore provides a useful history of epigenetics, including the changing meaning of the term itself. When first coined by Conrad Waddington in the 1940s, epigenetics referred to a branch of biology studying the internal interactions between genes and the cellular products bringing phenotype into being. Its contemporary definition, however, has expanded to emphasize the external environment and the molecules literally acting “on top of” the genome (hence the “epi” in epigenetics).

After a comprehensive review of DNA, RNA, protein, and regulation, Moore explores the technics of epigenetics and the radical influence of environment on human development in part 2, “What Do We Know?” Chapters 8 and 9 cover the best-known mechanisms of epigenetic regulation: DNA methylation and histone acetylation. What makes these admittedly genetics-dense sections so intriguing—and what makes epigenetics so compelling to biologists—is that such epigenetic marks provide biochemical explanations for previously inexplicable phenomena across nature. For example, entomologists have long known that providing “royal jelly” to bee larvae determines their fate as either workers or queens, but how exactly does royal jelly work? The answer involves epigenetics of course, and more specifically the demethylation of specific development genes. Later chapters explore the epigenetic effects related to maternal intimacy (chapter 10), memory formation (chapter 13) and nutrition...