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Henry J. Strain
Cootehill, County Cavan, Ireland
No two people have ever been found to have the same fingerprint. There are three basic patterns – arches, loops and whorls. Various combinations of these three patterns also occur. However, fingerprint identification is not based on patterns, but on the coincident sequence of individual characteristics, such as ridge endings or bifurcations. The number of characteristics required in law varies by jurisdiction. In the UK it is 16 and in Ireland, 12. Some countries accept a lower number.
Simon McLeish
Lechlade, Gloucestershire, UK
The best test for shared fingerprints comes from identical twins: they differ. This means that it is pretty certain that they’re all different, even though, if an accident damages a fingerprint, it will grow back with the same pattern (as long as there isn’t scarring).
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Fingerprint identification is not based on patterns, but on the coincident sequence of individual characteristics
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The interesting follow-up question is, why should there be such diversity in them? The arch, loop and whorl patterns also cover toes, palms and soles. As that suggests, the equivalent to prints are present in more animals, and they appear in all primates and koalas. This shows that they are the result of convergent evolution.
It is likely that the reason that they are evolutionarily useful is simply that grip is enhanced by the ridges and valleys, especially in animals that move rapidly in trees.
Guy Cox
Sydney, Australia
In a Scientific American article (29 May 2009), interviewed expert Kasey Wertheim said yes, and who am I to disagree with that? But that doesn’t mean that we all have them, and in my case, I don’t. If you lack them from birth, that is a genetic condition called adermatoglyphia, which is rare. You can also lose them from cancer chemotherapy, but mine have just worn off during my fairly long life, and that is actually not so rare. In my case, it is probably from lab chemicals, but handling rough materials, as in bricklaying, or using alkaline substances, such as lime, can all cause it. And it can be a hassle when travelling.
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