What determines fingerprints? Is it a random process or is it something inherited from our parents?
Mike Follows
Sutton Coldfield, West Midlands, UK
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Fingerprints begin to form in the 10th week of gestation. Some researchers think they are caused by tension between the outer layer of the skin (the epidermis) and the layer underneath it (the dermis), which results in tiny folds in the skin’s surface.
An alternative hypothesis is that their formation might be the result of something called a , driven by biochemistry. Alan Turing is better known for breaking the Nazi Enigma code, but, in 1952, he explained animal patterning – how leopards get their spots and zebras get their stripes, for example. Each pattern is individual to each animal and the same mechanism might also explain why we all end up with unique fingerprints.
In Turing’s “reaction-diffusion model”, molecules behave as either activators or inhibitors. The activator molecules replicate themselves, but produce inhibitor molecules at the same time.
A ridge in the skin forms when the concentration of activator molecules reaches a critical level. But the inhibitor molecules diffuse faster, so, once the concentration of the inhibitor exceeds that of the activator, the ridge comes to an end. The activator molecules act like fires spreading out from lots of different places simultaneously, while the inhibitor molecules behave like firefighters who outrun the fires to create firebreaks.
Despite following the same principle of formation, each pattern is unique. This is because the places where the activator molecules reach a critical concentration are random.
Research published in the journal Cell earlier this year shows that genetics also plays a key role. This reveals that are genetically correlated with hand and finger proportions, and that the genes for limb development influence the patterns of whorls, arches and loops that characterise our fingerprints.
Heather Riley
via Facebook
My father was a fingerprint expert, and was always being asked to look at our fingerprints to see if they had any special features.
From my grandparents down the generations, there were the usual loops and whorls and the occasional arch. Then you get to my daughter, who has eight arches and two unusual whorls.
My father told her: ” That’s incredibly rare, behave yourself!”
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