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

It is relatively commonplace for linguists to assume that language is in the mind and that the mind is the result of the activity of the brain. But how do mental phenomena, like language, actually arise from the biology? Gary Marcus has provided a highly readable introduction to the relevant science, informed by questions important to both linguists and psychologists, that discusses how the mind/brain derives from the genes. A credible theory of the mind, and therefore of language, must at some point deal with, or at least rest comfortably with, basic biological matters, and in contemporary biology, this necessarily involves genetics. Rational though this may sound, it remains highly unusual for researchers to directly address the genetic basis of mental phenomena in humans. M has provided a most valuable resource that takes on this issue, and he has done it with sophistication, readability, and even a good dose of humor—a rare and welcome combination. M’s book is a must-read for any linguist who cares about the psychological and biological reality of grammar, and for any scholar who wishes to gain some insight into the even broader questions (‘paradoxes’ as M refers to them) of how the mind can be both richly structured and at the same time highly flexible, and how it can emerge from such a (relatively) small genome of only 30,000 or so genes.

A question of enduring interest, whether in consideration of language acquisition or of the basic nature of linguistic knowledge, involves the relative contributions of nature (innate capacities, the genes) and nurture (environment, the input data). As M explains, these are not separable: absent an environment, genes are useless; absent its genes, no organism can use the environment. A further important lesson provided in Ch. 1 is that the genome-as-blueprint metaphor is highly misleading.

Ch. 2 addresses the fact that humans, sensitive to the statistical properties of the world and also able to both imitate and generalize from given information, come equipped with the mental mechanisms (nature) that allow us to learn from what is out there in the world (nurture). Humans are born able to learn language, and to do so under almost any circumstances. For M, there is no real debate about whether language acquisition is innate, but rather about which learning mechanisms are special for language.

The human newborn’s brain has the same overall organization as the adult brain. Nature provides an initial configuration that nurture (experience) then modifies. The main point of Ch. 3 is that the newborn brain is prewired, not hardwired. Young brains adapt and change, but they are organized in advance of experience. Neurons are subject to how developmental rules—genes—work. They are influenced by their neighbors but can also reflect their source. Hence, just as there are initial (prewiring) constraints, there are limits on plasticity.

Ch. 4 gives a succinct conceptual history of the gene and then explains how genes provide recipes for proteins, including information about when the protein is to be made. ‘Understanding how genomes contribute to the construction of body and brain is … a matter of understanding how the two parts of every gene—the regulatory IF and the protein template then—work together to guide the fates of individual cells’ (60). Cells are not distinguished by what genes they contain, but by which ones are switched on. Importantly, the then of one gene can satisfy the if of another, turning it on, and thus, through iterations of this process, a single gene can cause a cascade of hundreds of thousands of others. The switching on of one gene can result in a large and significant development.

Genes work to create the brain just as they do any other part of the body; neurons do have special qualities but they are just specializations of the general...