Steven Rose - In Search of the God Neuron

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The Guardian UK posted this excellent books review by Steven Rose, in which he looks at the latest theories about the human brain.

In search of the God neuron

Steven Rose examines the latest theories about the human brain

Steven Rose

The Guardian, Saturday 27 December 2008

Article history

Splendours and Miseries of the Brain
by Semir Zeki
234pp, Wiley/Blackwell, £16.99

Accidental Mind: How Brain Evolution Has Given Us Love, Memory, Dreams, and God
by David J Linden
276pp, Harvard, £13.95

The Evolution of Morality
by Richard Joyce
271pp, MIT Press, £11.95

Damasio's Error and Descartes' Truth
by Andrew Gluck
145pp, Chicago, £9

Half a century ago, passionate to study the brain, I began my graduate research in a gloomy, red-brick building in south-east London - the Maudsley Institute of Psychiatry. In the biochemistry department I was rapidly disabused of any idea that my research might lead to a greater understanding of how the brain could be "the organ of mind" - and still less that it might provide any help for the hospital's patients, whom I could dimly see through my laboratory windows. Neurochemistry meant grinding rats' brains up and extracting their enzymes; neuroanatomy was about cutting thin slices and staining them to be viewed under the microscope; neurophysiology was sticking minute electrodes into nerve cells and checking their electrical responses. To articulate the thought that this might tell one anything about "higher nervous functions" was strictly out of bounds. A dozen years ago, I heard a young American physiologist describe the study of consciousness as a "CLM" - a career limiting move. No topic for a young and ambitious neuroscientist, best left for those old enough to be experiencing the "philosopause" - said to affect scientists who had run out of research steam.

How times have changed! What was once dangerous territory is now the hottest theme in brain research. The subtitle of Semir Zeki's excellent new book is Love, Creativity and the Quest for Human Happiness. David Linden's is brasher: How Brain Evolution Has Given Us Love, Memory, Dreams, and God. Richard Joyce goes even further in claiming that our very morality is an evolved property of the brain. The rupture with the past is striking. From the ancients to the 20th century, it was philosophers who speculated about how the mind and brain might work. Now it is neuroscientists who are displacing the philosophers and theologians and telling us how we must behave. Three hundred years ago, David Hume argued that one could not derive an ought from an is, but now we are being told that our "oughts" - our moral feelings - are indeed "ises", genetically and developmentally incarnated in our brains. Whole new scientific disciplines - neuroeconomics, neuroethics, neuroaesthetics - are emerging. No wonder that an issue of Science, timed for November's US election, claimed that brain imaging could identify voting intentions.

Against these reductionist claims, the Jesuit philosopher Andrew Gluck attempts a spirited, but to my mind ultimately unsuccessful, rebuttal. His title makes reference to the neurologist Antonio Damasio, whose major book Descartes' Error and its succeeding volumes laid two charges against Cartesian philosophy. The first, the one that concerns Gluck, is Descartes's dualism, in which an immaterial soul interacts with a material brain through the pineal gland. Not so, says Damasio, and neuroscientists overwhelmingly agree: we are, and have to be, materialists. The world is made of one stuff, not two. Gluck demurs, accepting materialism for the physical sciences, idealism for the mind.

Damasio's second charge is perhaps more interesting - if not to Gluck, then to cognitive neuroscientists who see the brain as a problem-solving machine. On the contrary, brains are not primarily cognitive devices designed to solve chess problems, but evolved organs adapted to enhance the survival chances of the organisms they inhabit. Their primary role is to respond to the challenges the environment presents by providing the cellular apparatus enabling the brain's owner to assess current situations, compare them with past experience, and generate the appropriate emotions and hence actions. It is this evolutionary imperative within the particular line of descent leading to Homo sapiens that has resulted in our large and complex brains. As feminist sociologist Hilary Rose points out, Descartes's famous "cogito ergo sum" should be replaced by "amo, ergo sum."

However, our brains are indeed complex almost beyond comprehension. A hundred billion neurons (nerve cells) in each human cortex; perhaps a hundred trillion connections (synapses) between them. The numbers make even the US budget deficit look small. Most of the neurons are present at birth, which means that, averaged over the entire nine months from conception they are being born at the rate of about 250,000 per minute. Most of the synapses, however, mature after birth, giving ample opportunity for the connections to be modulated by experience. This is the tension between hard-wiring - specificity - and adaptation, or plasticity. Daringly, Zeki describes these wiring patterns as concepts - the brain, he claims, has both inherited and acquired concepts, a reductionism I'll return to shortly.

Each neuron has its intricate biochemistry; ensembles of neurons are grouped into modules, modules into systems concerned with sensory inputs and motor responses, emotional experience, spatial learning and many more. There is no general "command centre"; rather, all regions are connected by multiple bidirectional pathways, making the brain the paradigm of a self-organising distributed system. Linden provides an accessible and up to date guide through this maze, if you can cope with an excessively cheerful transatlantic style. But even he can't disguise the fact that when, each year, around 30,000 researchers meet at the American Society for Neuroscience jamboree, they mainly talk past one another. Biochemists and brain imagers may be studying the same hunk of tissue or function, but with very different methods and research programmes.

Take memory, my own research subject over the decades, as an example. I can tell you in molecular terms precisely what happens in particular regions of a young chick's brain in the minutes or hours following training on a simple task - which is pretty much the same as what happens in rats and mice too. Are these chemical changes to the brain correlates of memory, as many molecular biologists fondly believe? Or should memory be sought in the transient activity of cells in the brain regions that light up when I put my head in an imaging device and recall my fourth birthday party or what I bought in the supermarket last week? Both research programmes study what they call memory, but are they really exploring the same phenomenon?

So where in this tangle of neurons, synapses and systems should one look for love, creativity, morals and even God? In each cell's DNA, in individual neurons, or in ensembles of cells? Or is this even a valid question? To be sure, it is possible by stimulating particular brain regions to evoke sensations, memories, even emotions, but this does not mean that the particular memory or whatever is physically located in the region, merely that activity in that region may be a necessary correlate of the memory. The truth is that we don't have a comprehensive brain theory that lets us bridge the gaps between molecules, cells and systems, to enable us to begin to answer the question - which Linden cheerfully refers to as "that middle thing". Until we know this, isn't it a bit pretentious to think we can deal with the really big questions?

Zeki doesn't think so. One of the world's leading visual neurophysiologists, he has turned to brain imaging to explore matters as seemingly outside brain science's territory as beauty in literature and art - and even "romantic love". His scope is dauntingly ambitious, though his basic thesis is straightforward. The brain's hard-wiring provides the basis for the concepts of beauty that we all possess. However, it is the cultural context in which we develop that shapes what we actually find beautiful, and hence which particular art work or potential sexual partner we fall for. Furthermore, brains have evolved to deal with ambiguity. Hence our interest in the ambiguous images of a Necker cube or an Escher drawing. And, more controversially, the ambiguities of some seemingly unfinished great works of art, from Michelangelo to Cézanne. This is the brain-dependent neuroaesthetics - a term Zeki has made his own - with which a major part of his book deals.

Zeki has gone on to test part of his thesis in a fascinating and imaginative experiment, recruiting a group of young men and women who claimed to be "truly, deeply and madly in love" and imaging their brains as they look at photographs of their beloveds. Zeki and his colleagues identified specific brain regions that on average were more active when subjects viewed their lover's face than more neutral ones, such as friends of a similar age - much more fun than my own attempt at imaging people recalling their favourite supermarket purchases. Of course, there are always technical criticisms that can be levelled at such experiments, and brain imaging, involving underlying assumptions about the relationships between blood flow and neural activity, as well as complex mathematical transformations, is notoriously capable of over-interpretation, but the results are thought-provoking, and at the very least there's nothing inherently improbable about finding brain regions associated with emotional responses being activated in this way.

My problem with Zeki's argument is more fundamental. In what sense is it appropriate to say that the brain, an assemblage of interconnected cells, has "concepts", whether inherited or acquired? "Acquisition of knowledge," he says early in the book, "is a principal function of the brain." In this he is at one with many other leading neuroscientists. "You are your brain," says Nobel prize-winner Eric Kandel; "You are nothing but a bunch of neurons," wrote Francis Crick. The problem with this reductionism is to equate a part with a whole - an error I was fully guilty of when, many years ago, I wrote a book incautiously called The Conscious Brain. But it simply won't do. For sure, the brain is "the organ of mind" - always bearing in mind(!) that brains are in bodies, which have their physiological role to play. There are, it is chastening to note, as many nerve cells in the gut as there are in the brain.

However, it is not brains that have concepts or acquire knowledge. It is people, using their brains. To paraphrase the anthropologist Tim Ingold, I need legs to walk, but I don't say "my legs are walking". Similarly, I need my brain to think, but it is I, not my brain, who does the thinking. Indeed, Zeki gives the game away when he quotes Kant as saying "The Mind does not derive its laws ... from nature but prescribes them to her" and goes on to say "he might as well have been writing about the brain". No, no; the mind may need the brain, but it is not reducible to it, and we neuroscientists need to recognise our limitations. Of course, such reductionism is not confined to my trade (think of The Selfish Gene), but it is currently rampant among neuroscientists - as in the title of a recently formed Society for Molecular and Cellular Cognition.

Which brings me finally to Richard Joyce and the evolution of morality. For some years now, stretching back to EO Wilson in the 1970s, speculative evolutionary psychologists have been attempting to come to terms with David Hume's ought/is distinction. The questions are whether there are universal codes of moral behaviour, and if so, how did they emerge in humanity's evolutionary past. The claim that there are such "universals" has been explored by psychologists presenting toy ethical problems to their students, featuring such unlikely scenarios as whether they would be prepared to push a fat man over a railway bridge into the path of an oncoming train to stop the train and thus save the lives of a group of railway workers further down the track. Apparently many of us would jib at this, but would pull a lever to divert the train even though it would certainly kill a solitary man on the track.

I find these abstract scenarios unconvincing as predictions of what people would really do in such circumstances. However, evolution has resulted in a human species whose members are social animals, living in communities in which individuals need to cooperate to survive. Our offspring are born neotenous, initially helpless and for several years in need of parental care to survive and mature. These two features, among others, require that we learn to help others in our community whether or not they are closely genetically related, not to cheat or renege on our commitments to others, and so on. In this very general sense, how we think and behave are just as much part of our evolutionary heritage as are our average lifespan or limited sense organs.

Joyce makes an interesting distinction, though. If such behaviours are encoded within our DNA (or in how our brains develop) then they cannot be considered moral, for we have no choice but to behave that way. Morality only emerges if we are presented with a genuine choice of behaviours, so that we need to decide what we "ought" to do. I'm not sure how much this helps us. We may be born with a propensity to behave morally, just as Zeki argues that we are born with an inherited concept of beauty or of falling romantically in love. But any such propensity can only be expressed developmentally, shaped by the society and culture in which we are immersed. And clearly, what is regarded as morally appropriate varies across cultures and historical time. Take the prohibition expressed by the commandment that "thou shalt not kill another human". Is this "ought" statement a moral universal? Perhaps, but the Greeks did not think this prohibition extended to barbarians, and their philosophers could justify genocide. Capital punishment is still morally acceptable in many US states, just as it was in Britain until relatively recently - and, opinion polls show, it would still be acceptable to many Britons.

Killing the enemy in war, and even dying in the process oneself, as the flurry of articles and TV programmes around November 11 reminded us, remains "dulce et decorum". Dropping a one-tonne bomb as part of a "targeted assassination" or blowing oneself up as a suicide bomber in retaliation are both seen as morally appropriate acts. And one of our princes went off on his tour of duty in Afghanistan displaying the slogan that his task was "to do bad things to bad people". The concept of a universal sense of morality thus lacks any explanatory purchase on the way that we behave in any particular circumstances. This is not to collapse into Gluck's idealism, but to recognise that the biological is not the right level at which to seek to explain many crucial aspects of how and why we do what we do.

If humans do have an evolved sense of morality, or indeed of beauty or romantic love, the evidence shows that in practice our standards are remarkably flexible. Under these circumstances, to seek for their neurobiological correlates may be on a par with hunting the crock of gold at the end of the rainbow. With the difference that the gold could at least be put to practical use.

• Steven Rose's The 21st Century Brain: Explaining, Mending and Manipulating the Mind is published by Vintage. To order Accidental Mind for £12.95, The Evolution of Morality for £10.95 or Damasio's Error and Descartes' Truth for £9, all with free UK p&p, call Guardian book service on 0870 836 0875 or go to guardian.co.uk/bookshop

Tags: books, brain, Psychology, consciousness, Steven Rose, In Search of the God Neuron, Splendours and Miseries of the Brain, Semir Zeki, Accidental Mind, How Brain Evolution Has Given Us Love Memory Dreams and God, David J Linden, The Evolution of Morality, Richard Joyce, Damasio's Error and Descartes' Truth, Andrew Gluck