The Accidental Mind: How Brain Evolution Has Given Us Love, Memory, Dreams, and God [Paperback]

 

 

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The greatest fear among those who reject Charles Darwin's "Dangerous Idea" is the implications the concept holds for human beings. Our brain, they often claim, demonstrates how far we are from the other animals. It must have been designed by "divine intelligence". Not so, says David Linden. Our brain is something cobbled together over millions of years, parts and functions being added over time to produce that kilogramme of matter in our heads. He likens the building-up process to a multi-scoop ice cream cone. In this finely written overview, he explains the brain's structure and functions, relating them to earlier sources with clarity and wit.

The bottom of the ice-cream cone is the brainstem, an ancient structure controlling much of the body's major systems like heartbeat and breathing. Many of the body's communication with the rest of the brain pass through this part. Above the brainstem is the cerebellum, the first "scoop". The cerebellum acts as a signal filter, inhibiting "expected" sensations like your clothing against your skin. When something detectable as not part of "normal" conditions arises, the cerebellum passes those signals to the rest of the brain. That's when the real action begins. Above the cerebellum lies the midbrain, which is the first recipient of visual and sound signals. In some animals, such as frogs, he notes, this is the primary sensory area. Our midbrain, Linden declares, is symbolic of what he calls "brain kludge". It's an archaic region retained from earlier ancestral creatures for very limited processes. Moving upward and forward we encounter two elements, the thalamus and hypothalamus, the former being a major relay station for signals within and to and from the brain. Near these two is the amygdala, the centre of fear and aggression - the "flight or fight" controller that is an obvious holdover from early times.

If there is a "human" area in our brains, it is the cortex. In dealing with its role, the author takes us through how neuronal cells are structured and operate. They are, he notes, a flawed example of "design". Brains are often compared to computers, but the network of neuronal cells is a patchwork of bad connections, leaking signals and is depressingly slow. Copper wire is several orders of magnitude better at passing information. Describing somebody as being "quick minded" reveals we don't really know what's going on in there. There are, Linden reminds us, 100 billion neurons residing in the brain, with 500 trillion synapses - the contact point for brain signals - connecting them. But the distribution is unequal with contact points ranging from 0 to 200 000. No wonder some thoughts "go astray" and "memory fails"!

Knowledge of the brain rests heavily on those who have suffered injury or lesions in particular areas. Today, these are identified by electronic scanners, but no account of the brain would be complete without the early 19th Century story of Phineas Gage. A steel rod through his skull failed to kill him, but his personality was changed forever. Linden recounts the studies initiated by this accident, and goes on to describe the roots of other behaviour traits. He discusses vision, hearing, sleep and dreaming, and, of course, sex. Studies performed on what happens in the brain during orgasm make almost hilarious reading. Even Linden is left wondering just how the subjects coped. His explanation of why humans seem to bond better than other creatures, even our primate cousins is of particular interest. Although the word "love" appears in the subtitle, there's little mention of it in the text. It's not really related to how the brain works. You are cautioned not to jump to Chapter Six before reading the introductory material.

Linden's chapter on why humans have religion is necessarily thin. Little work has been done on this topic. Even what has been done is rudimentary and sketchy. He compares some representative ideas about gods and spirits, noting that there is some uniformity among them. He dismisses any suggestion of a "god part of the brain" or genes prompting for "faith". Instead, he says, there is a tendency for the brain, seen in other mental functions such as vision, to seek "coherent, gap-free stories". The brain "fills in" when it isn't receiving continuous information. There are many forms of this "filling-in", as some patients have exhibited, which Linden refers to as "confabulation". This isn't a form of "making up" stories, since the individuals truly believe what they are saying. They simply have no way of knowing the tale isn't true. It was a surprise to this reviewer that no mention of sensory deprivation studies dealing with this topic was introduced by the author.

Finally, as all writers of science in the US seem compelled to do, Linden responds the rising challenge of "intelligent design". The simple answer is that the notion is a weak attempt to explain what is either unknown or poorly understood. Why US scientists or science journalists must descend to sparring with this elusive concept is both astonishing and worrying. Many astute thinkers and writers have demolished "ID". Why does it need yet another post-mortem? Linden does as good a job as any at demonstrating the falsity of proponents like Behe, Dembski and Johnson. In doing so, he concludes with an appeal for more work to build on what is known about the brain and its evolutionary foundation. [stephen a. haines - Ottawa, Canada]

The mind is what the brain does. Fortunately, throughout a process lasting several thousand years, evolutionary improvement of the brain has expanded and increased substantially the mind's capabilities. To the best of my knowledge, no computer has as yet been constructed that can duplicate what the mind does. Think about this: Until now, the finest human minds have been unable to improve on a design that David Linden characterizes as "a cobbled-together mess." Later in the book, he refers to the brain's systems as a "Rube Goldberg contraption." Reuben Lucius Goldberg (1883-1970) was an American cartoonist, sculptor, author, engineer and inventor who gained renown for inventing immensely complicated machines that could perform the simplest of tasks, such as filling a spoon with sugar.

What he offers in this book is to be his reader's guide to a "strange and often illogical world of neural function," pointing out during the guided tour "the most unusual and counterintuitive aspects of brain and neural design and explaining how they mold our lives." To what does the book's title refer? Linden offers an explanation (of sorts) on Pages 240-242 when explaining accidental design. What about intelligent design? "The idea of intelligent design is an assertion," not a reality

I wish I had known about Figure 9.2 on Page 244 when I began to read this book. "The Main Evolutionary Constraints on Brain Design" encapsulates the main arguments of Linden's book.

Others have shared their reasons for holding this book in such high regard. I agree with those reasons, of course, while adding two of my own:

First, to the extent possible, unlike Rube Goldberg, Linden explains even the most complicated terms and processes in layman's terms. He does NOT dumb down the material. Rather, he uses a nomenclature that creates access to much of the material for those who such as I who took only the required science courses and refuse to remember anything about them.

Also, I really appreciate Linden's wit. He immediately establishes and then sustains a personal, almost (not quite) collegial rapport with his reader. There is a playful, sometimes irreverent tone to his many of his comments. He obviously enjoys learning and seems to enjoy helping others to learn at least as much.

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