Biology 202

2006 Book Commentaries

On Serendip

Steven Pinker's The Language Instinct seeks to convince the reader in 448 well-written pages that the capacity for language is a uniquely human ability that is built in to our brains. Moving smoothly from the origins of language to the perception and production of language to the modern evolution of language and missing nothing in between, Pinker keeps the reader captivated throughout the book with humorous illustrations of his reasoning and charming anecdotes. The most interesting points in Pinker's book are seemingly unrelated, but they have a common thread that isn't just their link to language. The sections about why language must be partially learned, why infants aren't born speaking, and how grammar develops neurologically are fascinating looks into how learning takes place on a neurological level.

In his chapter entitled "The Tower of Babel" about the origin of the thousands of modern human languages, Pinker argues that it is obvious why language must be partially learned. To begin with, an inborn vocabulary of 60,000 words (an estimate of the size of an average high school graduate's vocabulary – imagine that of a Bryn Mawr student!) would be incredibly unlikely to have evolved, especially since new things are being discovered and invented at a much faster rate than evolution is occurring. In a more compelling argument, Pinker goes on to hypothesize that because language is very much a shared ability, it would be in everyone's best interest to be able to adapt to others in the group. If language were completely innate, no one would be able to communicate effectively with another person. Genes mutate and vary so much that over time, everyone would have completely different and unintelligible grammars. Learning parts of language may be a way people to continue to have a single, shared universal grammar.

In class, we discussed only briefly the interaction between genes and the environment. There was enough information to conclude that genes influence behavior but never cause anything by themselves; there is always some environmental influence over the expression of traits. Based on this way of thinking, as well as Pinker's sharing of grammar hypothesis, it makes sense that language is not one hundred percent innate.

Pinker's next interesting chapter, and arguably the section of the book I am most fascinated by, deals with the development of language in children. Although I've studied developmental psychology before and have learned about the developmental timeline of language, this was the first time I've heard a hypothesis as to why children begin talking when they do. The explanation is a neurological one; although almost all of a person's neurons have been formed and are in place when a baby is born, the number of synapses between neurons continues to increase for several years after birth. The number of synapses in an infant's brain peaks between nine months and two years, which is conveniently when most children experience the bulk of their language development. After this, the number of synapses declines over time.

From here, things seem to fall into place. From our class discussion of the structure of the nervous system as well as my own knowledge from other courses, it makes perfect sense that language should develop at a time of vastly increased synaptic levels. More synapses mean more connections between neurons, which mean a greater potential for neural circuits to be established. If some grammar must be learned, as theorized earlier, then a multitude of possible pathways are necessary for internalizing what a child learns.

In order to fully understand the way language develops, it is necessary to look at the smallest boxes in the nervous system – neurons. Pinker gives a brief description of how neurons work followed by a simple theoretical network for several grammatical constructions. His explanation is concise and easily accessible to even the least knowledgeable reader. Going into further depth, Pinker details the development of grammar on a neurological basis. He proposes a framework in which every neuron is initially connected to every other neuron, and maintains that as children learn to use certain constructions more than others (such as "went" instead of "goed" or "mice" instead of "mouses"), the synapses being used are strengthened, while others are weakened considerably. In this way, we can account for the gradual decline in children's ungrammatical speech over time.

This network proposal corresponds to the finding that the number of synapses peaks and then declines after age two; as correct grammatical constructions are learned, the synapses that would have been strengthened due to incorrect usage weaken. Additionally, it seems that grammar may be controlled by central pattern generators. Speech is not broken down into individual behaviors; it is a chain of coordinated behavior that seems to maintain itself. It seems only logical that grammar, which is made up of such a complex network of neurons, could be under the control of central pattern generators.

The neural basis of learning, which seems to be the subject in Pinker's book that has captured my attention the most, was something we did not touch on in class, but it is something I've read about for other classes. It would have been very interesting to discuss the formation of central pattern generators over time from experience, like the one that Pinker seems to be proposing for grammar. This would have been, in my mind, an appealing way to bring together a lot of what we talked about during the course of the semester. Learning is one of the most powerful ways to see the brain and behavior change together, and language is such an important part of the human experience that it seems to interest everyone.

I would recommend The Language Instinct for its humor alone, but Pinker's careful and clear explanation of language makes it a necessary read for anyone interested in any aspect of language. Pinker's book has something for everyone, whether you want to learn about the big picture issues of the universality of language and the origins of language or the microscopic topics of the neural structure and genetics of language.


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