Chapter 1
Chapter 2
Chapter 3
Chapter 4
Chapter 5
Chapter 6
Chapter 7
Chapter 8
Chapter 9
Chapter 10
Chapter 11
Chapter 12
Chapter 13
Subject index
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Individuality means different things. You think of yourself as an individual – you are different from anybody else in the world. Your biological make-up is different - there is unlikely to be anyone identical to you anywhere, unless you happen to have an identical twin, and even he/she will have differences. You look out into the world from the ‘person’ lying somewhere just behind your eyes: everyone else looks at you. Your experience is different from anybody else’s; even though the fabric of your life may be made up of familiar threads, the exact way they are woven makes a pattern di
fferent from everybody else’s. Even
if someone else had, extraordinarily, experienced everything you have
experienced, the results would still be different, since the
‘you’ to which all this has happened is different
from anybody else. Whether you are a socialite or a recluse, shy
or outgoing, other people make up a large part of your pattern of
life. Whilst we all think of ourselves as individuals,
taking our own decisions, in fact much of what we all do is
influenced, determined or directed by the other people, their
needs, their priorities as well as our own
necessities…….. The brain’s serotonin system is activated by stress. This may help the brain resist the stress or adapt to it. Released serotonin is sucked back into the nerves that contain it by a special protein (an uptake protein) which limits its action. The gene that makes this protein has a polymorphism (in this case one that involves a ‘repeated’ sequence). So a person can have either two ‘short’ forms (no repeat), two ‘long’ ones, or one of each. You can’t tell by looking at them. But should such a person be exposed to a ‘life event’ ( a bad stress) then something extraordinary emerges. Those with two ‘short’ genes (and hence a slightly altered duration of action of serotonin) are more likely to become depressed…….
The influence the genetic mix has in an individual may, in turn, depend on the nature of the challenge: resisting a period of starvation may be influenced by very different genetic patterns than, say, coping with sustained stress at work. But we can see the way forward, if dimly, into this immense jungle of genetic complexity. Over the next decade or so, this science will move progressively from statements about groups (‘middle management is more stressed and liable to heart attacks than the top brass’) to those about individuals (‘John Roe is middle manager with this genetic make-up, this early set of experiences, this current social environment, this set hormonal and other measures and his chance of a stress-related heart-attack is..…’ ). This will lead to an equally precise and individually-tailored ability to intervene before John gets his heart attack (‘if we lower/ increase John’s ….. by …… amount, then we will reduce his chances of an attack by ….; whereas in Jim it wouldn’t be worth it etc ’)….
Don’t let all this, fascinating as it may be, lull you into thinking that genes are the only formative influence on the brain we bring to the survival battle. The brain passes through a period during which it is particularly sensitive to either environmental or biochemical events. Individual differences in the way these occur can have long-lasting – some would say permanent – effects. This ‘critical’ period occurs during early life. For example, separate a baby rat from its mother for an hour or so for a few days; when it becomes adult it will show exaggerated stress responses compared to its sibling that has experienced a more tranquil maternal environment. Prenatal ‘stress’ may also have long-term effects: treat rat embryos with a hormone similar to cortisol (the stress hormone) and they show reduced growth, but also insulin resistance and abnormal levels of stress hormones as adults…………..
There’s a rather stri
king example of the importance of individual
differences in the limbic brain and the cortex. Show twenty
people a ham sandwich and a typewriter (to use a famous example) and
all will agree on which is which, and what is what.
That’s the cortex: it needs to be accurate about analysing the
environment or you won’t survive for long. Do it ten times
and you’ll get the same answer. But then ask the
twenty about how they feel about the ham sandwich. Those that have just eaten find it rather unappealing, whereas those that missed
lunch might find it very attractive. A few hours later, these
responses might be reversed. A vegetarian, or an orthodox Jew, or
someone with a food allergy to ham, might never want the ham sandwich.
Nobody, of course, tries to eat the typewriter. In contrast the
analytical cortex, the functional activity of the limbic system is
highly variable, either in the long or shorter term, depending on
wants, preferences and social customs……..Scientific and literary quotes.