They are used to reveal one’s identity when entering certain countries, to unlock one’s smartphone and even to elucidate criminal cases: fingerprints are the most infallible tool for identifying individuals. Well… that’s what we’ve been told for several centuries!
Since 1788, more precisely. At the time, a certain Johann Christoph Andreas Mayer, a German anatomist, concluded that each finger has a distinct pattern, even in the same individual. In other words, the identification of our ring finger is not the same as that of our little finger, etc. The famous fingerprints, specific to each person, are a unique signature.
A real turning point for investigators: police around the world are making fingerprinting their number one asset to find criminals who have left a thumb or middle finger mark here and there. It must be said that the method is particularly effective (in addition to being still good badass).
Once the print has been analyzed and its owner found, it is impossible to deny its presence at the crime scene! In 1892, the British anthropologist Francis Galton calculated that a false positive was of the order of one chance in 64 billion. A probability close to impossible, which confirms the absolute uniqueness of these small brands… really unique?
AI a problem in calculations
Let’s settle the question right away. YES, fingerprints are unique, in the sense that the chance that another individual has the same ones as you on this Earth is so small that it is difficult to imagine. So no double or twin fingerprints on the other side of the globe! Sniff.
On the other hand, they might not be as unique as we thought… within the same hand! As we have told you, researchers have been convinced for centuries that each print from each finger of the same hand is different. The one on your ring finger has nothing to do with the one on your little finger. An artificial intelligence (AI) says that’s just… wrong.
This AI was developed by researchers at Columbia University in New York (United States), based on a “Siamese” neural network model. It is able to compare two fingerprints and detect those coming from the same individual, even if they come from different fingers. Basically, she can tell you if that famous ring finger matches the little finger of the same hand, proving… that they’re not that unique after all.
Published in January 2024 in the journal Science Advances, the results are clear: the AI correctly identified nearly 77% of the pairs of prints coming from the same person and the precision increases when we consider several prints at the same time. In other words, the prints of different fingers of the same hand can have such similarities that they call into question their absolute uniqueness.
Useful prints every day
How could this have eluded scientists with decades of study for so long and not artificial intelligence? The latter simply does not take the same approach. Instead of focusing on the traditional minutiae used by forensic experts, she analyzes the curvature and angle of the lines in the central part of the prints. Much more efficient, askip.
Well, even though fingerprints may not be as unique as we thought for a long time, they are still a devilishly effective identification tool. Especially since this AI, as powerful as it is, requires a ton of databases and biometric information, enough to make the greatest dictatorships dream.
And if, from the beginning, you have been wondering what these strange fingerprints we are talking about are ultimately for, no need to switch to another article: two main hypotheses exist. One suggests that they make objects easier to grip, a bit like the bumps on a car tire, increasing grip, especially when objects are wet. The second shows that fingerprints greatly improve tactile sensitivity, particularly on fine textures. Unique or not, they do a lot of work.
