It's a great pleasure to be able to highly recommend this book. I was suspicious of it because of the hype sent from the publisher, and the extremely broad topic covered for a science book, but it turns out that this is really good science writing. Gary Marcus certainly knows his stuff and has a distinctive talent for making complex things crystal clear. More, he has an infectious positive enthusiasm for scientific exploration.
With most popular science books about the human mind, the author tends to allow the material to be organized by their political and moral thinking. By that I mean the way the author thinks about human reason, autonomy, free will, and the essential nature of humans in general. So we most often have authors interpreting scientific data to show how the mind is: hardwired (or flexibly changing during our lives); highly specialized (or a general purpose problem-solver), built from adapted computational modules (or is essentially a useful artifact or "spandrel").
Each of these different ways of selecting and interpreting the data reveals a different way of thinking about ourselves. A hardwired, specialized, modular brain gives a very different way of thinking about ourselves than does an autonomous reasoning agent, and the implications for morality and for politics are profound. While cognitive science and biology are our greatest allies in the physical understanding of the world, when we try to rely on science to understand ourselves, we have been forced to speculate and extrapolate from them heavily in trying to get an accurate picture of humanity.
I bring this up to illustrate why Gary Marcus' "Birth of the Mind" is such a notable book. Somehow he manages to steer a course between the jagged rocks of innateness, the whirlpools of environmental determinism, and even the usual awkward compromises. Marcus celebrates the triumph of interactionism (genes plus environments) not by simply claming it to be true but by explaining exactly what it means and what it tells us. This is not a speculation about how genes and minds might be related; it is a carefully built skeleton of the conceptual bridge between the two. "Nature and Nurture" are not waved away here but deeply engaged. "Nature" here is not a collection of guesses about how we acted in the stone age and the challenges we faced in our evolutionary history, but an exposition of cellular biology and the way genes guide the construction of minds as a direct consequence of how they construct bodies.
This is a wonderful change from the polemics we find too often in books discussing research in genetics, evolution, and human behavior. Marcus isn't entering into one side of the technical debates on human nature here as we find in much of the popular sociobiology literature and popular behavior genetics literature. He isn't arguing about whether the mind is modular or whether it is a product of evolution. Nor does he argue about whether we have a soul or free will. As his title implies he is rightly more concerned about specifically HOW the mind arises, and this in itself hints at useful answers to the thornier questions. The tone of this book is simply that of shedding much needed light on the entrance to a long path to growing scientific knowledge of ourselves. Marcus appreciates both what we know and what we don't yet know about the mind, and that's an extremely valuable quality for writing about such a complex topic.
The spirit here is similar to that of Matt Ridley's recent book on nature and nurture. It is based on the emerging technical consensus that genes are central players in virtually all processes in living things, yet that genomes are not blueprints but self-regulating recipes. A relatively tiny number of genes is able to guide the development of brains consisting of an enormous number of neurons, and miniscule changes in the genome can produce dramatic changes in the outcome. Yet people with the identical genome have neither identical brains nor identical minds.
The solution to this dilemma is the centerpiece of the book, and it is answered by the way the genes work. They act as recipes, but as self-regulating recipes. This, Marcus explains, is the answer to the two great paradoxes of the mind: (1) a relatively small number of genes can reliably guide the self-construction of such complex multi-cellular organisms, and (2) the body is elaborately structured by genetic information yet still so flexible to environmental influences during development.
These are important and difficult questions that have great implications for our lives, so it is admirable that Marcus has addressed them without any obvious political axe to grind regarding human nature.
The book starts off introducing the hard questions: the surprising ratio of genes to cells, and the confusing mixture of stable and flexible developmental outcomes.
It then describes how we come out of the womb not with empty or fully formed minds, but as well-prepared learning machines with amazing and previously mostly unsuspected talents for observing and remembering in particular ways. The distinction between a brain that is "hardwired" and one that is "prewired" is the next topic. The brain has a definite structure, but one that is built for flexible change. Even identical twins, who share exactly the same genes, have different brain structure. When the crucial concept of the self-regulating genetic recipe is introduced, we see how the brain is built in exactly the same way as the rest of the body.
Next we see how genes guide the way neuronal connections are laid down: both how the brain is wired and how its structure is revised over time.
There is a single chapter focusing on human evolution, particularly on our capacity for language. Language has long been the classic example of a "modular" ability, but Marcus takes a different slant here, genetic rather than sociobiological. The evolutionary origin of language is used to show specifically how a small number of genes can have huge evolutionary consequences.