18 February 2002 20:52 GMT
http://www.independent.co.uk/story.jsp?story=119045There is a story of a journalist who travels to a remote region of Sardinia (or was it Georgia?) in search of the oldest man in the world. She finds him and asks what his secret is. "No drinking, no smoking and no sex," the man says while a raucous party takes place in the next room. With the interview complete, the journalist finally sums up the courage to ask who is having such fun next door. "Oh, that's just my father having a few drinks and a smoke with the girls from the village," the old man says.
Apologies if you've heard this one before, but it serves a purpose. We like being told stories, and we like them especially when they upset the conventional view of the way the world is supposed to work. There is a variant on this theme which I suspect we have all heard at some time in our lives. Presented with the overwhelming evidence that smoking causes lung cancer, some people still cite an aged uncle or spritely granny who has smoked 40 cigarettes a day for every day of their lives "and it didn't do them any harm".
The debate over the measles, mumps and rubella (MMR) vaccine has followed a similar pattern. Harrowing accounts of individual families affected by autism fly in the face of the anonymous welter of data presented in the studiously turgid prose of the medical journals. It doesn't matter that study after study has found no link between MMR and autism, a single, disturbing account of how one child became ill following an injection is enough to sow the seeds of doubt in the minds of many parents.
This is not to say that anecdotal experiences are invalid from a scientific point of view. Far from it. Medical journals are full of case reports involving individual patients who have come to a doctor with an unusual or mysterious condition. But in trying to prove cause and effect within the population at large, it is numbers that count, not anecdotes.
It is an indisputable fact that 500 million doses of the MMR vaccine have been distributed in 90 countries over the past 30 years and no one has been able to establish a link with autism. Such numbers, however, can seem pretty meaningless to a mother or father of an autistic child who, they are convinced, has developed the disorder after an MMR jab. Why, they may ask, should we believe such figures when we know what happened to our own child?
A healthy mistrust of experts is no bad thing. Scientists are not infallible and it is right that society constantly questions the evidence on which politicians make their public-health pronouncements. The BSE disaster is often quoted in this context, and rightly so, although it was the politicians and not the scientists who said that there was no conceivable risk from eating beef. But what we perhaps should be aware of is our own deep-seated inclination to concentrate on individual horror stories at the expense of the bigger picture. The mass media know the power of the anecdotal case history, they know that a medical issue is not really a story until there is a name, a photograph and a set of quotes from the victim or their family to go with it. We are, in short, vulnerable to seeing potential tragedy in our own lives by following the story through the experiences of someone who has suffered the same fate.
There is a branch of science called evolutionary psychology which has a potential explanation for this phenomenon (although evolutionary psychologists have potential explanations for most things). The theory says that human minds are highly tuned in to bad-luck stories involving other people. The hyper-sensitivity once served to protect us against potential dangers in the environment. In crude terms, if there was a rampaging mammoth on the other side of the hill, we took more notice of the threat if we were told a terrible story of how someone had been trampled to death.
This neatly explains why a newspaper that decides only to print good news will quickly go out of business. The real reason we want to hear or read about bad news may not simply be because of some morbid fascination with the affairs of some sad strangers, but because we are perhaps genetically programmed to be tuned in and sensitive to any intelligence that could alert us to a potential threat to ourselves, and particularly our children.
This could once have helped us to make sense of an irrational world where threats came in many guises. It is perhaps why the rational explanation offered by science over the safety of the MMR vaccine hits a brick wall with many parents whose antennae are fine tuned to anecdote rather than mere data. Yes, many intelligent, middle-class parents know full well that it is irrational to ignore the scientific evidence and reject the triple jab, but the irrational side to their nature whispers something more powerful in their ear.
In a similar vein, we might all be fond of the story of a lone scientific maverick, such as Dr Andrew Wakefield whose research set off the MMR scare, fighting against the "establishment", but the fact is that the "alternative" view in science is very likely to be the wrong view, particularly after it has been subject to extensive peer review.
This does not mean that we should never listen to the maverick's case. Those who ask awkward questions play an important role in science, but their opinion should be tempered by the evidence on which the consensus view is based. We may wonder whether baby Leo has had the jab, but the truth is that it is irrelevant to the scientific case supporting the triple vaccine.