full of intricate, cleverly designed and interconnected systems that do not have control centres. The economy is such a system. The illusion that economies run better if somebody is put in charge of them - and decides what gets manufactured where and by whom - has done devastating harm to the wealth and health of peoples all over the world, not just in the former Soviet Union, but in the west as well.
From the Roman Empire to the European Union's high-definition television initiative, centralised decisions about what to invest in have been disastrously worse than the decentralised chaos of the market. Economies are not centralised systems; they are markets with decentralised, diffuse controls.
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It is the same with the body. You are not a brain running a body by switching on hormones. Nor are you a body running a genome by switching on hormone receptors. Nor are you a genome running a brain by switching on genes that switch on hormones. You are all of these at once.
Many of the oldest arguments in psychology boil down to misconceptions of this kind. The arguments for and against 'genetic determinism' presuppose that the involvement of the genome places it above and beyond the body. But as we have seen it is the body that switches on genes when it needs them, often in response to a more or less cerebral, or even conscious, reaction to external events.
You can raise your Cortisol levels just by thinking about stressful eventualities - even fictional ones. Likewise, the dispute between those who believe that a certain suffering is purely psychiatric and those who insist it has a physical cause - consider M E , or chronic fatigue syndrome - is missing the point entirely. The brain and the body are part of the same system. If the brain, responding to psychological stress, stimulates the release of Cortisol and Cortisol suppresses the reactivity of the immune system, then a dormant viral infection may well flare up, or a new one catch hold. The symptoms may indeed be physical and the causes psychological. If a disease affects the brain and alters the mood, the causes may be physical and the symptoms psychological.
This topic is known as psychoneuroimmunology, and it is slowly inching its way into fashion, mostly resisted by doctors and mostly hyped by faith healers of one kind or another. But the evidence is real enough. Chronically unhappy nurses have more episodes of cold sores than others who also carry the virus. People with anxious personalities have more outbreaks of genital herpes than sunny optimists. At West Point military academy, the students most likely to catch mononucleosis (glandular fever), and the ones most likely to get a severe illness from it if they do, are the ones who are most anxious and pressured by their work. Those who care for Alzheimer's patients (an especially stressful activity) have fewer disease-fighting T lymphocytes in their blood than expected. Those S T R E S S 153
who lived near Three Mile Island nuclear plant at the time of its accident had more cancers than expected three years later, not because they were exposed to radiation (they weren't), but because their Cortisol levels had risen, reducing the responsiveness of their immune system to cancer cells. Those bereaved by the death of a spouse have a less responsive immune system for several weeks afterwards. Children whose families have been riven by a parental argument in the previous week are more likely to catch viral infections. People with most psychological stress in their past get more colds than people who have led happy lives. And if you find these sorts of studies hard to believe, then most of them have been replicated in some form or another using mice or rats.1
Poor old Rene Descartes usually gets the blame for the dualism that has dominated western thinking and made us all so resistant to the idea that the mind can affect the body and the body can affect the mind, too. He barely deserves the blame for an error we all commit. In any case, the fault is not so much dualism — the notion of a separate mind detached from the material matter of the brain.
There is a far greater fallacy that we all commit, so easily that we never even notice it. We instinctively assume that bodily biochemistry is cause whereas behaviour is effect, an assumption we have taken to a ridiculous extent in considering the impact of genes upon our lives. If genes are involved in behaviour then it is they that are the cause and they that are deemed immutable. This is a mistake made not just by genetic determinists, but by their vociferous opponents, the people who say behaviour is 'not in the genes'; the people who deplore the fatalism and predestination implied, they say, by behaviour genetics. They give too much ground to their opponents by allowing this assumption to stand, for they tacitly admit that if genes are involved at all, then they are at the top of the hierarchy.
They forget that genes need to be switched on, and external events
- or free-willed behaviour — can switch on genes. Far from us lying at the mercy of our omnipotent genes, it is often our genes that lie at the mercy of us. If you go bungee jumping or take a stressful job, or repeatedly imagine a terrible fear, you will raise your Cortisol 1 5 4 G E N O M E
levels, and the Cortisol will dash about the body busy switching on genes. (It is also an indisputable fact that you can trigger activity in the 'happiness centres' of the brain with a deliberate smile, as surely as you trigger a smile with happy thoughts. It really does make you feel better to smile. The physical can be at the beck and call of the behavioural.)
Some of the best insights into the way behaviour alters gene expression come from studies of monkeys. Fortunately for those who believe in evolution, natural selection is an almost ridiculously thrifty designer and once she has hit upon a system of genes and hormones to indicate and respond to stress, she is loath to change it (we are ninety-eight per cent chimpanzees and ninety-four per cent baboons, remember). So the very same hormones work in the very same way in monkeys and switch on the very same genes.
There is a troop of baboons in east Africa whose bloodstream Cortisol levels have been closely studied. When a certain young male baboon attached himself to a new troop, as male baboons of a certain age are wont to do, he became highly aggressive as he fought to establish himself in the hierarchy of his chosen society. The result was a steep increase in the Cortisol concentration in his blood as well as that of his unwilling hosts. As his Cortisol (and testosterone) levels rose, so his lymphocyte count fell. His immune system bore the brunt of his behaviour. At the same time his blood began to contain less and less of the cholesterol bound to high-density lipoprotein (HDL). Such a fall is a classic precursor of furring up of the coronary arteries. Not only was the baboon, by his free-willed behaviour, altering his hormones, and hence the expression of his genes, he was thereby increasing his risk of both infection and coronary artery disease.2
Among monkeys kept in zoos, the ones whose arteries fur up are the ones at the foot of the pecking order. Bullied by their more senior colleagues, they are continuously stressed, their blood is rich in Cortisol, their brains are low in serotonin, their immune systems are permanently depressed and scar tissue builds up on the walls of their coronary arteries. Quite why is still a mystery. Many scientists now S T R E S S 155
believe that coronary disease is at least partly caused by infectious agents, such as chlamydia bacteria and herpes viruses. The effect of stress is to lower immune surveillance of these dormant infections which allows them to flourish. Perhaps, in this sense, heart disease in monkeys is infectious, though stress may play a role as well.
People are very like monkeys. The discovery that monkeys low in the hierarchy get heart disease came soon after the far more startling discovery that British civil servants working in Whitehall also get heart disease in proportion to their lowliness in the bureaucratic pecking order. In a massive, long-term study of 17,000 civil servants, an almost unbelievable conclusion emerged: the status of a person's job was more able to predict their
