The Inescapable Allure of the Reptile Brain

In the New York Times this morning, the poet Diane Ackerman has written an essay about the brain, in which she waxes eloquent about its ability to discern patterns in the world. The essay is distilled from her new book, An Alchemy of the Mind, which I’ve just reviewed for the Washington Post. I didn’t much like the book, although it took me a while to figure out what was bothering me about it. If you read the essay, you can get the flavor of the book, not to mention Ackerman’s general style in her previous books (which have taken on subjects such as endangered species and the senses). Ackerman has a fondness for sipping tea, tie-dye dresses, and hummingbird feeders, and an even greater fondness for writing about them. I know people who have been put off by her aesthetics, and I find them cloying as well. But that wasn’t really at the heart of my dislike of the book. (And besides, my own aesthetics leans towards shark tapeworms and dissected sheep brains, so I’m hardly one to complain about other people.) It took me a few days to realize that the problem with the book was embedded in a deeper problem: how we talk about nature (which includes our own minds).

By we, I don’t mean cognitive neuropsychologists or planetologists or molecular ecologists. I mean the rest of us, or the collective us, the ones who consciously or unconsciously create the language, metaphors, and stories that serve as our shared understanding of the world. The words we use, even in passing, to describe genes or brains or evolution can lock us into a view of nature that may be meaningful or misleading. When people say, "Being dull is just written into his DNA," they may only intend a light joke, but the metaphor conjures a false image of how personality emerges from genetics and environment and experience. This figure of speech may seem like nothing more than a figure of speech until people step into the office of a genetics counselor to find out about their unborn child.

The brain suffers from plenty of bad language. In some cases, the language is bad because it’s unimaginative. In Alchemy of the Mind, Ackerman points out that calling neurotransmitters and receptors keys and locks does a disservice to their soft, floppy nature. In other cases, though, the language is bad because it’s based on gross simplifications of outmoded ideas. Yet it survives, taking on a life of its own separate from the science. My favorite example, which I wrote about last year, is the bogus story you always hear about how we only use ten percent of your brain.

Ackerman indulges in this sort of bad language a lot. One example: she loves referring to our "reptile brain," as if there was a nub of unaltered neurons sitting at the core of our heads driving our basic instincts. The reality of the brain–and of evolution–is far more complex. The brain of reptilian forerunners of mammals was the scaffolding for a new mammal brain; the old components have been integrated so intimately with our "higher" brain regions that there’s no way to distinguish between the two in any fundamental way. Dopamine is an ancient neurotransmitter that provides a sense of anticipation and reward to other animals, including reptiles. But our most sophisticated abilities for learning abstract rules, carried out in our elaborate prefrontal cortex, depend on rewards of dopamine to lay down the proper connections between neurons. There isn’t a new brain and an old brain working here–just one system. Yet, despite all this, it remains seductive to use a phrase like "reptile brain." It conjures up lots of meanings. Ackerman floods her book with such language, which I grouse about other bad language in my review.

Which makes me wonder, as a science writer myself: is all poetry is ultimately dangerous? Does scientific understanding inevitably get abandoned as we turn to the juicy figure of speech?

Update: 6/14/04 11 AM: NY Times linked fixed