Sherlock Holmes was able to finger crooks by examining their footprints, though nowadays, the police use fingerprints, not footprints, to track down criminals. But it seems fingerprints might also give the medical profession some vital clues - about your future diseases.
The pads on your fingers are not perfectly smooth, but they have tiny ridges and valleys on them - supposedly to increase the friction, and give you a better grip. When you wrap your hand around a glass, and then remove it, you can see the impression of those ridges on the glass - your fingerprints.
Fingerprints have been used for identification for thousands of years. The ancient Chinese and Assyrians used fingerprints on legal documents. The ancient Kings of Babylon would press their entire right hand into a slab of clay carrying a decree, before it was fired. Even back then, it was a common belief that no two people shared the same fingerprint.
The first person to solve a crime with fingerprints was a Scottish doctor working in Japan, Henry Faulds. He matched the fingerprints found on a cup at a robbery in Tokyo with those of a servant, and described this feat in a letter to the prestigious science journal, Nature, in 1880.
In July 1892, an Argentinian police officer, Inspector Alvarez was investigating a crime in which two children had been beaten to death. Inspector Alvarez found a bloody thumb print on the door, so he just sawed out that section of the door, and took it along to the Police Station.
He then had the children's mother fingerprinted, and when she learnt that her own thumb print matched the thumb print on the door, she confessed to the crime. Shortly after, Argentina became the first country in the world to use fingerprints as the chief method of identifying offenders.
The famous American gangster John Dillinger burnt his fingerprints off with acid - but he could have saved himself the intense pain, because they grew back. John Phillips another gangster, had new fingerprints grafted onto his finger pads - but the police convicted him because they got a match with the prints further down his fingers.
There are three basic patterns used to classify fingerprints - the Arc, the Loop and the Whorl. The easiest way to picture them, is to imagine that you're looking at a map with contour lines, to show the hills and valleys - like a military map or a bushwalker's map. An 'arc' is a gentle rise, a 'loop' is a ridge, while a 'whorl' is a solitary hill or peak.
But the patterns of your fingerprints also have a medical significance. One study in India involved some 150 adult males, 90 of whom had duodenal ulcers. It found that there was a slight tendency for people with whorls to have more duodenal ulcers. Another study looking at American Japanese in Hawaii showed that if men had more whorls on their fingers, they were more likely to have a heart attack.
But it was a study by Professor David Barker, head of the Medical Research Council's Environmental Epidemiology Unit at Southampton General Hospital, which found that whorled fingerprints were associated with high blood pressure in adults.
He was examining high blood pressure, and was checking up records of various maternity units. He noticed that if babies had been born very thin, they were more likely to have whorls on their fingertips and to have high blood pressure when they became adults.
Now he and his team are not exactly sure what's going on, but it is well known that fingerprints are already laid down by the 19th week of gestation in the womb. And it's also known that if the foetus has flattened finger pads, it's more likely to have the simpler arch pattern or the slightly more complicated loop pattern.
But on the other hand, if the foetus had swollen finger pads, it's more likely to have a complex whorl pattern of ridges. But why would a baby who was going to be born thin, have fat finger pads?
One possible theory to explain this is that a fetus which is in distress might have a higher blood pressure, and this higher blood pressure and higher blood flow could show itself as increased swelling in the fingertips. But they're really not sure why there is a link between whorls and high blood pressure - but they do know the link is there.
Now it's still early days in this research, so there's no point in getting a magnifying glass and looking at your fingertips and getting paranoid. You should be proud of your fingerprints - they're your very own personal ID, which you always carry with you.
Various organisations try to collect fingerprints, but it's the FBI that has the biggest collection. They have over 170 million sets of fingerprints - but then, so does every house with small children!
Published 27 April 2001