The Birth of the Mind: How a Tiny Number of Genes Creates the Complexities of Human Thought

The mind is what the brain does." So wrote Massachusetts Institute of Technology psychologist Steven Pinker in his celebrated 1997 book, How the Mind Works (1). Today, and in the wake of the ongoing genetics revolution, Pinker's former student Gary Marcus takes a stab at answering the lofty question, What do our minds owe to nature, and what to nurture? Until recently, we knew relatively little about how genes work and what they bring to the biological structures that underlie the mind. Marcus reminds us that now, 50 years after the discovery of the molecular structure of DNA, we are for the first time in a position to understand directly DNA's contribution to the mind.

Marcus is a cognitive psychologist and is currently an associate professor in the department of psychology at New York University and director of New York University's infant language center. He understands genes and has researched his topic well, taking us on a complex journey in an entertaining and absorbing way. He does a particularly good job of framing the issues with crystal clarity and making relevant scientific concepts accessible to even the lay reader without diluting his logic or the power of the story for more knowledgeable readers.

Marcus explains how the emerging picture of nature's role in the formation of the mind is at odds with a conventional view that suggests a much more limited role for genes. He describes two key arguments that provide the basis for this view. The first is Stanford anthropologist Paul Ehrlich's "gene shortage" view, which states that genes can't be very important to the birth of the mind, because the human genome contains only about 30,000 genes, which is simply too few to account for the brain's complexity (2). The second is the brain plasticity argument, which posits that genes can't be very important because the developing brain is so flexible—for example, a child who loses a left cerebral hemisphere may recover the ability to speak.

As a compelling alternative to this static "gene as blueprint" model, Marcus describes a vital dance between nature and nurture in which genes provide us with options, and the environment—as well as the genes themselves through their protein products—influence which options are taken. Seen in this light, there is no "gene shortage"; the human genome provides a wide range of tools, but genetic expression is ultimately context dependent. This dynamic interaction between nature (genes) and nurture (environmental opportunities and options) sets the stage for powerful cascading effects that allow an enormous range of possible outcomes.

This highly readable book will appeal to anyone who has pondered mind-body dualism; its ample appendices will allow the more scientifically minded to drill down to greater levels of detail. By making the elegant argument that the brain and the body are assembled in exactly the same way, Marcus helps psychiatry assume a more enlightened position that can help lead to intellectual and financial parity with the rest of medicine. He concludes by giving us examples of how our greater understanding of the relationship between nature and nurture will likely lead to advances in the treatment of mental illness. In doing so, this book provides us a glimpse into what promises to be a pivotal next century.

Dr. Simpatico is associate professor of psychiatry and director of public-sector psychiatry at the University of Vermont College of Medicine in Burlington and medical director of the Vermont State Hospital.