Not being a scientist, policeman or celebrity chef, I know very little about DNA, other than it was detected in the 1940s. There being no electron microscopes in those days, its playful ‘double-helix’ structure remained elusive until cleverly guessed at by Nobel prizewinners Crick and Watson over a pint of bitter in a Cambridge pub, while a researcher called Rosalind someone-or-other, Franklin, did the messy stuff. Rather like the instruction manual for the pressure washer I bought the other day, DNA contains the blueprint for assembling any life form, including a human being, but (fortunately) without the nine pages of Health and Safety warnings in nine languages including – is it – Finnish? Do pressure washers work north of the Arctic circle?
People, it seems, are not so superior as we once thought. Apparently, one variety of rice plant contains five times as much DNA as that of the Vietnamese peasant who harvests it. Bacteria, too, exhibit complexity which allows them to mutate into disease carriers in response to environmental opportunities, such as raw chicken drummers; and threats, as from liberal doses of Toilet Duck. We have about three thousand useful genes strung out in pairs along our DNA, like Christmas-tree lights. Thousands more appear to have no function, they’re either redundant or we haven’t got to use them yet. They may still be useful. When the level of CO2 in the atmosphere exceeds the limits of breathability, new genes could switch on and some of us survive. With three thousand pairs, the four different sequences of genes create billions of possible combinations, all of whom can be seen milling around Oxford Circus tube station any day.
The interesting thing about DNA is that it is universal, common to everything on earth that isn’t basically made of silicon, like Ivania Trump. The iris patterns in your eyes, the shape of your ears, your fingerprints, your reaction to Britney Spears’ breakdown, everyone’s DNA is different. Think of snowflakes, all the same but essentially different. They say no two identical snowflakes have fallen in the history of the world. How they know that is a mystery, because the things have a habit of melting as soon as you look at them, but it helps to build the picture of a world of infinite complexity that scientists like to contemplate over the breakfast dishes. It’s a lot of snowflakes. It seems equally likely that no human being has ever resembled a rice plant, although somewhere back in the mists of evolutionary time we have common ancestors with plants and presumably some residual genes that pre-date the separation between green and red oxygen carriers, chlorophytes and haemoglobin. Well, most of us.
It’s said that the chance of mistaking one person’s DNA for another’s is a billion to one, and that is good enough evidence for any court to convict. Not even a US Immigration official would confuse Osama bin Laden with a bromeliad. So, it is in fact the similarities between our genes rather than the larger differences, the fractional separations, that make DNA useful as a means of establishing individual human identity. There are over seven billion people on the planet, so on the basis of DNA evidence the odds against any crime having been committed by only one person are seven to one, but we should let that go; the others are statistically likely to have the perfect alibi, that they were Chinese at the time.
DNA has been much in the news lately, after some high-profile murder cases in which the perpetrators were so stupid, they didn’t realise the police would match the DNA samples they had previously given them to the traces found in their car boots and on the victims’ clothes. As a result of those cases, some police and politicians think it would be a good idea to keep samples of everyone’s DNA on a computer database, so that whenever a crime is committed the suspect can be immediately identified and convicted.
There are good arguments for this. It would save the expense of sending criminals for trial, since there would be no need to ask a jury to decide their guilt or innocence: any scientist would do. And, if we could raise the criminals’ awareness of police forensic procedures, it might deter them from murdering people at all. In the murderous mind of even the stupidest criminal, the certainty of arrest as a deterrent has always outweighed the possibility of being subsequently hung. DNA testing is the surest way of avoiding the necessity to bring back hanging. Capital punishment in fact has been shown to be no deterrent at all: every murderer in history, even in societies where they like to wind out your entrails and force you to listen to Max Bygraves’ Greatest Hits while decapitating you with an unlubricated chainsaw, has always imagined they will get away with it. DNA matching will ensure that they don’t.
While the database makes it easier to get a DNA match from the scene of crime, or even to plant some, the authorities still have to arrest the suspect. Shoot-outs might become more common, while the efficient use of DNA requires the State to maintain surveillance of all its citizens, and their relatives visiting from Bangladesh, at all hours of the day and night. In some countries, they are already doing this. Anonymous grey boxes have appeared beside the motorways, keeping tabs on the movements of every vehicle in the country. Pulled over by the police recently for having tinted windows, I found that by the time I was asked to step into the back of their car to be given the third degree, my past life unspooling grimly before me, they already knew more about me than my mother does. I wasn’t invited to donate a cheeky swab, but it is only a matter of time before my DNA is matched with Vlad the Impaler, Joseph Goebbels and Alastair Campbell, characters with whom my ex-wife has compared me in the past. As DNA technology moves out into the shoppersphere, divorce, too, will become easier.
Ah, good. Tea and biscuits.