Book Review : An Inquiring Mind Checks Out the Brain
Vital Principles: The Molecular Mechanisms of Life by Andrew Scott (Basil Blackwell: $19.95; 256 pages)
One of the central unanswered questions of modern biology is whether chemistry is all there is to life. Is biology just a branch of chemistry, and is chemistry just a branch of physics?
To be sure, we are nowhere near having a complete chemical explanation for all living things, but in the end, is that what it will turn out to be?
Few people are altogether comfortable with that idea, but all we know strongly implies that we are just flesh and blood. Complex chemistry, to be sure, but chemistry nonetheless. This is called the reductionist position. Life is “just” chemistry.
If you think that’s wrong, you have to explain what else there is in your head that gives rise to thoughts, feelings, sensations and such. If there is a soul, where is it?
As you read these words, perhaps hearing them in your mind, the little voice that’s “speaking” them is nothing but a complex set of electrochemical changes in your brain.
If you don’t like that idea, come up with a better one. The field is wide open.
Search for Answers
Max Delbruck , who half a century ago taught biologists that they should be interested in biochemistry, believed that there would be special laws of physics that would be applicable to living things. He never found any.
Some biologists offer an alternative to reductionism without invoking spiritual or supernatural phenomena. They believe that while chemistry can explain a lot of life, it can’t explain all of it. They suggest that there are “emergent” principles that arise in unpredictable ways in the course of the predictable chemistry of life.
This is a guess. Much remains unknown, and everyone is free to think that it will follow rules that are known or rules that are so-far unknown. At the moment, it’s a matter of choice, a matter of faith.
But all of the evidence in hand argues in favor of reductionism, like it or not. As Andrew Scott puts it in “Vital Principles,” a book that makes the case for reductionism, “All living things are simply the end result of the physics and chemistry within them. . . . As far as we know life simply is chemistry.”
Basic Principles
Scott works from the bottom up, first explaining the basic principles of chemistry and physics, then showing how chemical reactions occur, then showing how they occur in living things. He writes:
“DNA makes RNA, which makes protein, which makes cells, including their DNA and RNA and protein: that is the central principle of life.”
All of the processes of life occur “mindlessly,” he says. All of the chemical regulation, the production of proteins, reproduction, all of it is the inevitable result of the laws of chemistry.
This discussion takes up the first three-fourths of the book, and, truth to tell, it’s rough going at times, despite Scott’s repeated assertions that he’s leaving out the details. Feel free to skim those parts where he’s put in too many of them.
The really interesting part comes in the last quarter of the book, where Scott turns to the higher brain functions in humans. Right off, he concedes that our knowledge is sketchy at best.
‘Mere’ Chemistry
To be sure, there is no evidence that there is anything at work in our brains besides “mere” chemistry. But how chemistry gives rise to consciousness is still a great mystery.
“As far as we know, our minds are created by our brains and by our brains alone,” Scott writes. “And the significant thing that happens in our brains is the transmission of nerve impulses. . . . All this ‘nervous activity’ is created and controlled by the activities of proteins and their specific interactions with the other chemicals of life; and, of course, the proteins are encoded by the genetic information in our genes.
“In essence, that is all that our enquiring minds have been able to discover about these minds, and it may be all there is to discover.”
If you share the central dogma of biology--as I do--you have faith that someday, probably not in our lifetimes, science will have a complete explanation of the chemistry of the brain. We will then be able to match every thought, every shading and nuance of emotion, every memory, with a specific chemical state. For the moment, however--and the moment may last a very long time--that is an article of faith.
“Sadly,” Scott says, “the deepest mysteries concern the questions we would most like to be able to answer.
“We are all living minds, and yet science cannot tell us exactly what a mind is, or what a thought, an idea or a sensation in our brain is. It can offer no really satisfactory answer to the puzzle of how inanimate matter composed of atoms and molecules and ions can give rise to the consciousness which is able to identify and confront such puzzles.”
