The Haphazard Construction
of the Human Mind

By Gary Marcus

Houghton Mifflin. 224 pp. $24

nolead ends nolead begins

Reviewed by Steve Mirsky

Furniture, self-confident, corner, adventuresome, chair, table, independent, television.

Early in

Kluge: The Haphazard Construction of the Human Mind

, author Gary Marcus asks the reader to memorize that short list of words. He then notes, "What follows is more fun if you really do try to memorize the list." So go ahead; it'll take only a few seconds.

Marcus then tells a short story, the gist of which is: "Donald often sought excitement. He had climbed Mount McKinley, kayaked rapids, driven in a demolition derby, piloted a jet-powered boat. He had risked death numerous times, and was now seeking new thrills."

Now your assignment: Sum up Donald in a single word.

Chances are your word is adventuresome. But had the list substituted for adventuresome the word reckless, your word choice would probably be more pejorative. The snap judgment of Donald is swayed by information - the word list - that should be irrelevant. Unfortunately, your brain turns out to be alarmingly bad at evaluating individual situations truly objectively.

"We are born to be suckered," Marcus claims in his short, entertaining look at why the mind is a kluge. The word is used by engineers to describe a clumsy or inelegant solution to a problem. The carbon dioxide filter that the Apollo 13 astronauts built in 1970 out of sweat socks, cardboard and plastic is the quintessential kluge - not perfect, but good enough.

How can what is often considered the most complex entity in the universe - the only thing known that can even begin to evaluate the universe's complexity - be just a klugey mess? Because evolution doesn't care about elegance. As Nobel laureate Francois Jacob noted, "Living organisms are historical structures: literally creations of history. They represent not a perfect product of engineering, but a patchwork of odd sets pieced together when and where opportunities arose."

(Also, keep in mind, so to speak, that the thing holding the mind in such high regard is itself.)

Marcus, a psychologist and director of the New York University Infant Language Learning Center, provides numerous examples of how easily the brain can be duped. For instance, researchers asked college students two questions: "How happy are you with your life in general?" and "How many dates did you have last month?" Students who were asked the questions in that order evaluated their happiness independently of their romantic involvements. But when subjects were asked about dating first, their evaluation of their happiness depended completely on their dating frequency. Victims of the phenomenon known as "focusing illusion," the students suddenly saw their entire lives through a particular, powerful prism.

Advertisers and pollsters can be experts at taking advantage of our brains' weaknesses - which is why conservative strategist Frank Luntz pushed for what was previously known as "global warming" to be referred to as the more benign-sounding "climate change," and now calls "energy exploration" what most people still think of as "oil drilling." (How might your opinion of Luntz change if that previous sentence had called him a "right-wing operative" instead of a "conservative strategist"?)

Humans are suckers, Marcus explains, because the brain wasn't designed in advance for optimal functioning. It's the product of hundreds of millions of years of evolution, which winds up putting together Rube Goldberg devices dependent on what already existed. After listing some of the commonly known cases of less-than-optimal structures - the mammalian eye has a blind spot; the spine is a poor load support - Marcus details how the evolutionary history of the brain makes it not perfect, but good enough.

The old hindbrain keeps us breathing, balanced and alert, just as it did our ancestors a half-billion years ago. The midbrain, built atop the hindbrain, does things like manage vision and hearing. The forebrain, the last addition, deals with language and decision-making - but not without the input of the other two regions. So the even more recently evolved "deliberative system," which works hard to defer the gratification of cheesecake in favor of your long-term weight-loss goal, is easily overwhelmed by the ancestral "reflexive system," which lives for the moment just in case those 800 calories are the last ones the organism will see for a while.

Marcus' greatest service is to remind readers that the mind is manifestly not the creation of so-called intelligent design. No deity, alien genius, or time-traveling molecular biologist (the trinity of possibilities called upon by the anti-evolution crowd to explain our alleged magnificence) would have cobbled together a brain subject to so many blunders. Only evolution would come up with a foolproof system for keeping your lungs on autopilot while you try to figure out where you left your car keys this time. Even though you may smoke a cigarette while you look for them.

Kluge was clearly meant to be short and pithy, which at times can frustrate the reader. The "mind versus brain problem" is left unexplored. In a section on the inefficiencies of language, Marcus says that people have tried to build more sensible languages "from the time of twelfth-century mystic Hildegard of Bingen." I needed to consult Wikipedia to find out whether Hildy was being used as a chronological reference point or actually worked on the problem. (She did, between her famous ocular migraines, which poor brain design led her to believe were divine visions.)

And Kluge happily references dozens of studies, but sadly without footnotes. A notes-listing then relates most, but not all, of the studies to page numbers. And an alphabetical reference listing then provides the studies' full citation. So Kluge is a kluge itself: not perfect, but good enough.

Steve Mirsky (smirsky@sciam.com/) is a writer for Scientific American, host of the magazine's weekly science podcast, "Science Talk" (http://www.sciam.com/podcast/), and author of "Anti Gravity: Allegedly Humorous Writing from Scientific American."