Steven Rose is a well-known public scientist who has dedicated his career to the study of brains. He has lived through the early days of the technical revolution that has involved increasingly powerful ways of imaging activity in the brain. But he is first of all a biologist. His guiding principle is that we cannot understand the human brain unless we understand how it came into being. He takes as his motto ‘Nothing in biology makes sense except in the light of evolution.’ That is the title of a spirited 1973 polemic against creationism by one of the great evolutionary geneticists, Theodosius Dobzhansky (1900-75).
The maxim suggests two ways of thinking about brains. One is implied directly: start at the beginning of life itself, tracing the appearance of more and more complex living creatures, some of which develop organs that better and better perform brain-like functions. This evolutionary story allows us to begin to understand the constraints governing the structure of complex brains, including our own. The design problems are fascinating: the ways that the different intercommunicating organs within the brain can be made to fit into a skull; which evolutionary paths were followed to end up where we are; and which paths lead to other viable animals. A good deal of the early part of the evolutionary story can be no more than plausible speculation, but whether or not Rose’s speculations are sound, they serve to organise information and understanding in a helpful way.
A second method is implied indirectly by Dobzhansky’s maxim. We should start at the beginning of the life of a human being, and trace the way that an egg becomes a person. A new design problem comes along. An incredibly complex organ, the brain, along with the rest of the body and its nervous system, has to grow in the womb and to continue growing through childhood, starting from nothing much more than a set of instructions. The egg, then the foetus, then the infant, develops into a fully brained human as the skull and its contents grow in a world rich in experience of people and things. The infant brain weighs 350 grammes, the adult one at least 1300 grammes, although it reaches 95 per cent of its adult weight when a child is ten. And most of the growth happens in the first two years.
To a certain extent the first stages of brain formation for a human being will have to recapitulate the evolutionary progress: it would be absurd to postulate two different ways of achieving the same structure. But much else besides will contribute to the manufacture of a single body with a brain from virtually nothing. Rose is fully content to say that a newborn is not quite human (which has nothing to do with rights to life and care). It is born half-hatched, at a developmental stage midway between that of mice and that of guinea pigs. The latter have fur and run after their mother the moment they leave the womb, while newborn mice are roughly as developed as premature babies born early in the third trimester. Rose’s attitude is clear: to be fully human does not mean merely possessing a brain that weighs at least 1300 grammes. The brain also has to become part of a social person.
Rose is a biologist, but not a molecular one and not just a biologist of organs. He is a biologist of the whole living being. All creatures are in their own ways social creatures, be they wood ants, turtles or politicians. He is the kind of biologist – the most common kind – who emphasises complexity, and he does not want to reduce the complex to simpler structures or formulae. Next to Dobzhansky’s mantra, perhaps the most common line in the book is ‘We just don’t know.’
There is a side benefit, at least for me, of the doubly historical approach, evolutionary and developmental, which Rose takes in The 21st-Century Brain. I recall a lovely book by James Thurber and E.B. White, Is Sex Necessary?, among other things a spoof on sex manuals. In their day (1929) these handbooks had a lot of drawings of genital organs, with parts labelled, that made no sense at all. Thurber and White proposed these should be replaced by maps of South America. That tends to be my reaction to the diagrams and photographs and Latinate names in earnest popular books about the brain. But start to think of it as a design problem – how to fit all those functions into a fairly rigid container that also communicates with the rest of a body? which successive stages of evolution would lead to the various solutions we find in different species of animal? – and the structure of the brain begins to make sense.
I do not mean that Rose is doing reverse engineering. Steven Pinker, one of Rose’s bêtes noires, has suggested that we look at the brain and ask how we would make an instrument like that. So has Daniel Dennett. But for Rose, the question is simply historical: observe as best we can, with a bit of imagination, how simple, slightly brainy creatures evolved into increasingly complex systems. Not just humans, and not just mammals: observe how different solutions evolved for so many kinds of creature, each of which survived, each of which is, tautologically, ‘fit’.
But where is the 21st-century brain in all this? Half these pages are about the past, about how anything like a brain evolved out of the swamp, and how human brains gradually form in the womb and later become parts of people with minds. There are virtually two books here. One is a reflective, mildly philosophical account of mind and brain and how they come into being. The second is more practical, about the ways new technologies and chemicals are already affecting our brains, and what they may do in the next few years. These chapters are very, very cautious (‘we just don’t know’). Both parts pack in an amazing amount of information, gracefully told anecdotes, and a certain amount of social-democratic ‘attitude’. But there is a trade-off. Wisdom, good sense and socialist instincts tend to make things bland. I should admit that most of Rose’s judgments are my prejudices. So I am not a good critic. I only wish that some of the arguments were tighter, more conclusive. He tends to dismiss other people’s ideas rather than refuting them.
One aspect of the futurology of brain science is now of special interest to baby-boomers and older people. (Rose tells us all too often that he is – like me – a grandparent past the age of retirement.) If we do not die, soon enough we will become increasingly senile. Many of us will develop dementia or its more specific form, Alzheimer’s disease. That name seems to scare people nowadays more than cancer does.
The first chapter of the second part of the book has an upbeat title, ‘Ageing Brains, Wiser Minds?’ Seven pages of agreeable reflections on the pleasures and pains of growing old. (Not much romanticism: ‘ageing is not for wimps.’) Then seven pages on neurodegeneration: a little on Parkinson’s, more on Alzheimer’s. On the latter, there is important information that seldom sees the light in popular writing. Alzheimer’s disease is a very specific form of dementia. We know very well what happens with Alzheimer’s, but none of our present scanning technologies can tell if a living brain has been affected. Alzheimer’s can be conclusively diagnosed only after you are dead, on autopsy. That does not matter much today, because little can be done in terms of medical treatment.
What happens to the brain is that neurons die as they fill with tangled threads of molecules called fibrils. Patches of an insoluble substance rather like starch accumulate between cells in the brain. In the 19th century, French doctors adopted the term plaque for various inexplicable patches that appeared on tissue, as in multiple sclerosis (sclérose en plaques). Plaques show up in many diseases, and we seldom know why. Rose explains that Alzheimer’s is a matter of quantity. Such degeneration goes on in all ageing human brains, but at nothing like the same rampant speed.
Alois Alzheimer was not much interested in the phenomenon he observed in 1906, in a 51-year-old corpse. The pathology had been known for decades, but his effective boss, Emil Kraepelin, was much taken by it and named it after Alzheimer. Kraepelin was the most influential classifier of mental disorders of his day. His doctrine was that since we do not know many of their causes, diseases should be classified by symptoms. The standard or notorious American Diagnostic and Statistical Manual of Mental Disorders, after a couple of editions which tried to classify in part by causes, signed on to the Kraepelinian nosology in 1980, and has stayed with it.
Alzheimer himself was inclined to think that the condition he revealed should not be described as a disease at all. This is still debated in some quarters: some see it as ‘natural’ degeneration that will affect anyone who lives long enough. It just happens – so goes that opinion – that some people degenerate earlier than other people do, which is as true of our hips as of our brains. Another thought: perhaps we should reclassify it not as a disease but as a handicap or disability, which would substantially change its status and administration within the social net.
What Alzheimer observed was a very rare condition, now called early-onset Alzheimer’s disease, which can appear before the age of 40, and kills quickly. It runs in families and not in many of them. Most of the time, when people talk about Alzheimer’s they mean late-onset. It shows up in some 60-year-olds, and is quite common among 80-year-olds. Rose does not say that Alzheimer’s virtually disappeared from diagnosis soon after 1912, when Kraepelin declared that the early-onset type was one of three fundamentally distinct types of dementia.
Alzheimer’s was revived in about 1970, not by the medical profession, but because the children of senile Americans began clamouring for more attention, more funds for research, more support for care. Alzheimer’s as a diagnosis is a product of advocacy groups. It is an absolutely objective neurological condition, but it might not have been remembered had it not been for the vigorous lobbying of associations of families whose elderly members had dementia. The history of late 20th-century medicine will be not only a history of truly breathtaking triumphs, especially in the field of engineering that we call surgery, and a history of the pharmacological industry, but also a history of advocacy groups. Think of autism.
Today’s genetic imperative implies a vast drive to find genes for Alzheimer’s. A decade ago success was reported, when alleles that code for various forms of a protein involved in cell communication were investigated. The different forms of these alleles provide risk factors for Alzheimer’s. As Rose reports, the factors are not predictive. Some people who inherit the bad allele do not develop the disorder before they die of old age, while some with the good allele do.
This is a chapter in which Rose might well have included more instances of his cautious sentence: ‘We just don’t know.’ It has been said for him, however. When it turns to causes, a fact sheet issued by the Alzheimer’s Disease Society of Great Britain states: ‘The short answer is, we don’t know.’ We do know some things. We know that the nostrums currently available do not work. We do know that women are far more susceptible than men of the same age.
We think we know that Alzheimer’s is a curiously human failing. It could not show up in the wild, for old mammals die too soon. Rose says it does not show up in geriatric cats, dogs or donkeys. (Though we create genetically modified mice with something like Alzheimer’s, for experimental purposes.) The peculiarly human character of Alzheimer’s ought to be a significant clue, given the evolutionary similarities among mammal brains. Soon we will know a lot more about this, thanks to the Chimpanzee Health Improvement, Maintenance and Protection Act in the US, one of the last acts of the Clinton administration. In Louisiana, a retirement home for chimps used in medical and cognitive research will hold up to 200 ageing chimpanzees by the end of next year. But their research years have not ended. A phalanx of mammal gerontologists is about to move in.
There is now a controversial veterinary diagnosis of Cognitive Dysfunction Syndrome in aged dogs. I am told that the neurology department of one of the great schools of veterinary medicine denies there is such a thing, while across the campus, the animal behaviour department has shown that 62 per cent of dogs aged between 11 and 16 have CDS. Rose makes many comments on the way the pharmaceutical industry helps shape diagnoses; it is by no means a passive participant that finds cures for known disorders. Pfizer, the folks who provide Viagra to old men, now offer Anipryl to old dogs with CDS; its publicity cites the 62 per cent study. I wonder who paid for that study, by the way?
In the West, Alzheimer’s affects poor people more than rich ones; it is conjectured that this is not the usual socio-economic correlation with illness, but that rich people tend to have more mentally taxing occupations than poorer ones. Rose sensibly says that whether or not the motto ‘use it or lose it’ is correct, an old person is more likely to be more contented knitting or playing card games than mindlessly watching television. Rose suggests crossword puzzles, but those are very much a fetish of the English middle classes. And knitting rides poorly with osteoarthritis, another degenerative problem – but then again, some elderly ladies claim it is the knitting that keeps the arthritis at bay.
A question for the epidemiologists not posed by Rose: is there a difference in incidence between traditional poor families in which the elders are surrounded by tumultuous grandchildren or great-grandchildren, who are a good deal more mentally taxing than crossword puzzles, and the modern old person or couple living in relative isolation? We are always wondering why there is so much more depression, autism, bipolar disorder and Alzheimer’s around than ever before. Answers are manifold, and in the case of Alzheimer’s the prime factor is more old people, but the decline of the extended family living under one roof could well be relevant.
Rose has a very useful couple of paragraphs on the biochemical cascade of events that produces the plaques and tangles. Somewhere along the way we ought to be able to interrupt the cascade, but the question is how. Rose mentions a possibility investigated by his own group, but with typical honesty does not hype it. And we have to remember that much dementia is not Alzheimer’s. Moreover, Alzheimer’s often occurs together with another fairly precisely defined type of dementia called vascular dementia.
Those of us not affected yet, either in self or family, tend to equate Alzheimer’s with memory loss, and that is what Rose inevitably emphasises. We forget the ‘agitation, aggression, hallucinations, delusions and other behavioural and psychiatric symptoms of Alzheimer’s’: I am quoting from the summer 2005 newsletter of the Northern California-Northern Nevada Alzheimer’s Association for families and carers. Alzheimer himself laid as much weight on ill-directed aggression and anger as on memory loss. Families often give up and surrender a relative to an institution because of these psychiatric symptoms, and not because of memory loss, incontinence and the like.
I hope this long account of what Rose does and does not say about Alzheimer’s gives the tenor not only of the chapter, but also of similar chapters discussing other current issues in the practical sciences of mind and brain. There’s a sound discussion of Ritalin and Attention Deficit Hyperactivity Disorder. He thinks that the massive use of this drug in America (he could have added south-west Australia, and other places) is not only dangerous but also a frightening indicator of how a society may increasingly produce normality not by state decree but by a combination of drugs and what appear to be personal decisions by individuals.
He writes about conjectured drugs to make you smart. He is, as always, sceptical. If they were practicable, wouldn’t their use in examinations be classed as unfair, just as steroids are banned in athletics? The social democrat emerges here, as often in these pages. We seem to have given up worrying about the unfair advantages of the middle and upper classes who ensure that their children go to excellent schools that make them ‘smarter’ than the average, or smarter than they would otherwise be.
There’s a certain kind of analytic philosopher who finds the language of many neuroscientific popularisers pretty hair-raising. This is especially true of those of us on whom mid-20th-century English philosophy (e.g. Wittgenstein or J.L. Austin or both) left a mark. The most sustained display of raised hair can be found in Philosophical Foundations of Neuroscience (2003) by M.R. Bennett, an Australian neuroscientist, and P.M.S. Hacker, the Oxford interpreter of Wittgenstein. Rose has pretty much acquired the same philosophical sensibilities. There is hardly a sentence here that would seriously offend even Hacker.
Rose suggests that he may be philosophically tone deaf, because he cannot take seriously the intense discussions about the way our experience of the colour red connects with what goes on in the brain when we see something red. He suggests that there are two languages for describing connected events, a neural language and a language of experience. The second language is one that we share with many other people – it is not a private language at all. Now Peter Hacker would express the thought differently, but in my opinion Rose and Hacker are not much at odds with each other. I do not think that Rose is philosophically tone deaf at all – but I did say that my prejudices are too close to his judgments for me to be a reliable critic.
For decades students of mind and/or brain said very little about consciousness. Then in the early 1990s there was a stampede. The most widely advertised book must have been Francis Crick’s The Astonishing Hypothesis: The Scientific Search for the Soul (1994): ‘Consciousness is the great unsolved problem of biology.’ Among philosophers, the most influential work was David Chalmers’s The Conscious Mind (1996): ‘Consciousness is the biggest mystery.’ Thomas Huxley wrote, 140 years ago:
We class sensations along with emotions and volitions and thoughts, under the common head of states of consciousness. But what consciousness is, we know not, and how it is that anything so remarkable as a state of consciousness comes about as the result of irritating nervous tissue, is just as unaccountable as the appearance of the Djinn when Aladdin rubbed his lamp.
Rose appears not to share the sense of mystery. ‘I will try to explain why I think that as neuroscientists we don’t have anything very much useful to say about this particular Big C, and why therefore, as Wittgenstein said many years ago, we would do better to keep silent.’ That is a slightly ambiguous enunciation, sounding merely like a play on the last sentence of Wittgenstein’s Tractatus, which is not about consciousness, just about being silent about that of which we cannot speak. But later on Wittgenstein did make us think about consciousness. A small minority of living philosophers, including myself, think that he indicated why we should not ask the question ‘What is consciousness?’ It is not just that neuroscientists have no very useful answer, but that the question is a mistake. As usual my prejudice coincides with Rose’s judgment.
Rose himself trod the consciousness runway long before it was so fashionable: ‘Confession time. Many years ago in the green arrogance of my youth I wrote a book called The Conscious Brain’ (1973). Perhaps this is an instance of Rose’s ageing brain and wiser mind. But does he explain why neuroscientists do not have much that is useful to say about consciousness? Not to my satisfaction.
He challenges statements like this one: ‘Everybody knows what consciousness is; it is what abandons you every night when you fall into dreamless sleep and returns the next morning when you wake up’ (a psychiatrist, Giulio Tononi, in one of the endless multidisciplinary conferences, this one published in 2003). Rose says that is a narrow definition, one that suits philosophers who want to study subjectivity. Not all of them: not those who think that consciousness is a peculiarly human phenomenon. Horses and dogs and bunny rabbits wake up too.
Rose prefers David Lodge’s account in Consciousness and the Novel (2003) to Tononi. Being conscious, Rose agrees with Lodge, is being aware of who one is, one’s past, one’s hopes, and ‘the culture and social formations within which one lives’. Rose discusses the new discipline of ‘the ‘cognitive neuroscience of human social behaviour’. This leads on to the conjectured (proven?) mirror neurons that fire when I imitate a movement you have made, neurons that may be essential for understanding other people, or even for understanding that there are other people much like me. Such neurons, it has been suggested, do not fire in the right way in autistic children.
There cannot be any consciousness without content, Rose continues. It is constituted by its content. And, Rose ends with a flourish, the content of consciousness is not just what is going on now, but ‘all past moments in the history of the individual’. What?
I shall not try to make sense of that conclusion. No one is conscious of all past moments in their history. The idea is weirdly reminiscent of John Locke. In itself, that is fitting, for it was he who put the word ‘consciousness’ into serious circulation, partly as an alternative to Descartes’s ‘thinking’ (of the cogito). Locke wanted a definition of personal identity, and he found it in consciousness: I am identical with anything I am conscious of, which includes anything I can remember – ‘all past moments in the history of the individual’. Locke embraced, amazingly, a conclusion I am sure Rose would resist: if I don’t remember, it wasn’t me. If I got drunk and have no recollection of what I did, then I did not do it, and am not responsible for what was done.
This is no place to quarrel with Rose’s Lockean conception of consciousness. I fully respect the notion of consciousness involving a relational, social element. I sometimes encourage the idea that memory itself is more relational than solipsistically individual, that it is more in the realm of ‘human social behaviour’ than merely personal recall. But that does not mean there is no room for another idea of consciousness, something like present subjective awareness. Not only awareness of something, but also anxiety, for example, which need not be directed at any particular danger or discomfort.
Rose merely asserts that neuroscientists have nothing much to say about consciousness as present awareness. For example, he mentions Antonio Damasio’s proposal that consciousness evolved very late in animal history, and depends on specific structures in the brain. I have reservations about Damasio’s enthusiasms, but he has an important idea. It certainly accords with Dobzhansky’s maxim that ‘nothing in biology makes sense except in the light of evolution.’ Rose dismisses it as Damasio’s ‘heroic attempts to deduce the neuroanatomy of feelings, and self-awareness’. The implication of ‘heroic attempts’ is that they do not work. Why? No argument is given. Why shouldn’t neurologists try to understand the radical transition noted by Tononi, between sleeping and waking, between not being conscious and being conscious? What is wrong with John Searle’s statement (in a recent letter to the New York Review of Books), that ‘it is just a plain fact that neuronal processes do cause feelings, and we need to try to understand how’? Rose does not explain why he thinks that all these thinkers are barking up a non-tree.
I am something of an outsider to these debates, but I do not think these are non-trees. Rose needs to make distinctions. I think he and I would agree (prejudices again) that there is a sprawling phantom tree, the mystery-of-consciousness tree that has attracted so much philosophical attention. Rose’s philosophical good taste finds most of that a waste of time. But here he misses an ally in Daniel Dennett, who cannot abide that stuff either. Dennett favours a computational rather than a biological approach to the brain, for which Rose has no use. Hence he cannot pick up on the insights that come with Dennett’s tirades against mysteries and ‘qualia’.
There are phantoms out there (I say), but there are also solid trees that require both neuroscience and conceptual clarification from anyone ready to lend a hand. What does happen when mammals wake from sound sleep? It has little to do with specifically human consciousness, although there are doubtless human aspects to it. For example, what happens in the brain when I fall asleep thinking about a problem and in the moments of waking come up with a solution? That is largely a neurological question, but it has the best philosophical pedigree. Locke gave us the word ‘consciousness’ precisely to escape what he took to be the mad Cartesian notion that, since I exist when I sleep, I must be thinking every nocturnal moment.
On another tack, Damasio has solid proposals in his emphasis on feeling as a late-evolved human neurological function, whose evolutionary role is to monitor and modify states of body and brain. Indeed he has recently been touting the neurological interest of Freud’s unconscious, though I think what he needs is a concept closer to Leibniz’s petites perceptions, innumerable goings on which would be like perceptions if only we were conscious of them, and which sometimes do build up into real awareness. After Damasio’s books Descartes’s Error and Looking for Spinoza, one of his students might consider writing Found it! Leibniz!
To complete the trio of substantial trees I have already mentioned (there are lots more), Searle’s question does seem sensible. There may be nothing neurological in common between feeling sad, feeling sore, and feeling that there must be something in Chalmers even if I cannot see quite what excites my colleagues so. But surely brain processes are involved in all three. It is a serious research question, whether there is a specific type of process for each type of feeling, or whether our ways of talking are very bad maps of neurological processes. (In philosophical jargon, started by Donald Davidson: is it token-token or type-type identity?) And it is a serious question, mostly conceptual, but also empirical, whether what Searle wants to know about the brain and feelings overlaps with, or is even the same as, what Damasio’s school tries to investigate.
I have written this review around only two of Rose’s topics, consciousness and Alzheimer’s. They may seem about as unconnected as could be, but recall once again that we have the word ‘consciousness’ only because Locke wanted it to provide an understanding of personal identity. He further explained it in terms of memories. When people say, ‘Granny isn’t there any more,’ they are saying that that person has somehow gone missing as various types of memory go out of action. Unlike people, civilisations seldom forget. Few read Locke, but we in the West have a very Lockean conception of Alzheimer’s disease.