Résumé: "If it works, don't fix it!", runs the old adage. Any engineer will tell you, however, that this is false confidence. What works today may not work tomorrow when conditions change. Animal brains worked for many millions of years. Then Homo sapiens arose somewhere in Africa with an enlarged, busy brain. Combined with walking and handiness, that brain accomplished - and still accomplishes - wondrous things. Until you wonder where you left your car keys. Gary Marcus, in this fluidly written review, backed by a wealth of references, explains how the workings of our brain have been built up over time, with bits added or enhanced through the ages. It makes us a unique species, but it's anything but a fine design. Instead it's what engineers call a "kluge" - an inelegant, marginally efficient product of evolutionary bits cobbled together well enough to get the job done.

Using the fact of our brains having an evolutionary foundation, Marcus shows how Shakespeare's and the Bible's depictions of the brain are flawed. We have poor, erratic memories, we make irrational decisions, and we'll believe things that are patently untrue - sometimes with real tenacity. Our brains are built up from very ancient structures, probably using the same processes, with added complexity developing over time ["This worked last time, but it's not working now. Cobble something up to fix it."]. Knowing that readers might be overwhelmed with data overload [our memories can't handle it!], the author focusses on a half-dozen aspects of brain "design" demonstrating the positive features and the shortfalls. Memory, Belief, Choice, Language, Pleasure and "Things Fall Apart" - distractions. In each case, he explains how the system is usually depicted, what might be the ideal process, and how it actually works.

The opening segment on Memory lays the groundwork for the entire book. "If evolution is so good at making things work well, why is our memory so hit and miss?" Marcus compares human memory with computer memory. Nothing is lost on the computer's disk and any stored information can be retrieved. It was clearly "designed" for that task. Human memory, on the other hand, lacks access, lacks specificity, lacks reliability. We can retrieve old memories, but can't recall what we had for dinner yesterday. Nor can we assume that old memory, which seems so vivid, is valid. Marcus describes computer memory as "postal code" memory due to the system's design in making an "address book" used to find data. Human memory, along with that of other animals, is "contextual" - recollection comes within a frame of reference. That might be good or bad, depending on the circumstances, but it's hardly reliable or consistent.

The author's use of comparison in memory is followed by similar scenarios in the other sections. Language is particularly vague and imprecise, why does each language have its own version of the sound of a dog's bark. Yet, our brains allow us to work out meaning in contextual ways. Choice seems to be one of the most irregular mechanisms in our brains, since we continue to avoid shifting from decisions resulting in long-term benefits for short-term gains. Those limited scope decisions likely have links with the brain's pleasure centres, hence the current rise in addictions - even video games take time better spent at exercise or learning.

The conclusion of this book may come as a surprise. The unthinking may tend to see this section as one of those "self-help" manuals so common today [and which are designed to overcome the "kluge" aspects of our minds]. Here, Marcus is able to line out a set of recommendations for improving how we use our brains. He recognises that the idea of the human brain as a kluge will find little appeal with some people. That's a prejudice that must be overcome. Evolution, he reminds us, has produced things of tremendous beauty. If the brain falls short, it has the capacity to examine imperfection and understand it. More importantly, those imperfections of the brain can be addressed. Who is capable of that? You are. Don't miss this book. It's about you. [stephen a. haines - Ottawa, Canada]