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I still love how people simply assume fingerprints are unique even though there has never actually been any studies with a large enough sample size to make that

I still love how people simply assume fingerprints are unique even though there has never actually been any studies with a large enough sample size to make that determination Fingerprinting, at least for the purposes of criminal investigations is pseudo-science at best, akin to the now debunked microscopic hair analysis. DNA is always given as a probabilistic statement "there is a 1:1,000,000 chance this DNA belongs to someone else" However with fingerprints, like microscopic hair analysis, it was simply match/no match... a binary state that is given far far far more weight than it should. The perceptions of the examiner weigh heavily on the outcome. Finger print examining is an art form, not a scientific discipline

fractallyte 11y ago
How could they be anything other than unique? A fingerprint is a 'function' of a unique individual. You might as well claim that human faces aren't unique. Bear in mind, of course: the degree of uniqueness between two samples is determined by the metrics used to distinguish between them. I don't know the state-of-the-art with fingerprint analysis, but with a purely physical measure, how can fingerprints not be unique?
- lmm 11y ago
  At that kind of physical level every time the same individual is fingerprinted you get a slightly different result.
- the_ancient 11y ago
  I am saying there is no study to prove they are, thus one must assume they are not. Further there is not be a study to see if my left index may match your right middle finger, etc. I do not believe there is enough possible entropy for ~74 billion 100% unique never to be repeated patterns on finger prints... (7.4billion humans x 10 fingers per human)
- dalke 11y ago
  Many people have problem telling identical twins apart, so under that metric it's true that human faces aren't globally unique. There's even a project to find "twin strangers", which has had some success (see the images at the bottom of https://twinstrangers.net/ https://twinstrangers.net/ , though they also had the same makeup applied, which makes them look even closer). > how can fingerprints not be unique? How can the hash of two different strings be the same? It's all part of the Birthday Paradox, combined with that it means two identify two physical objects as the same thing. Now, at some point no two human-scale objects are the same. Even with two mass-produced objects, there are slight variations in production because of non-zero tolerances. For example, two sequential $1 bills differ of course by the serial number, but also contain minute differences in the paper. So as you say, we need to distinguish between how fingerprint analysis is done, vs. the most detailed possible analysis. And we know of several cases where fingerprint identification has been incorrect. One is Brandon Mayfield, a US attorney who the FBI believe, on the basis of a fingerprint match, to have been one of the Madrid bombers. As a result of that case, and similar ones, people have started to ask the police and others for data which shows that "all fingerprints are unique" is really true. This myth started over 100 years ago, but was based on a small sample size. There's never been the analysis needed to figure out the actual error rate, especially if there are, say, 100 million entries in the system. See also https://en.wikipedia.org/wiki/Fingerprint#Validity https://en.wikipedia.org/wiki/Fingerprint#Validity . And notice how that Wikipedia page also includes "No two fingerprints have ever been found identical in many billions of human and automated computer comparisons.[citation needed]". Where is that citation?
- mobiuscog 11y ago
  Probability is not a guarantee. Randomness does not guarantee uniqueness.

fractallyte 11y ago

How could they be anything other than unique? A fingerprint is a 'function' of a unique individual. You might as well claim that human faces aren't unique. Bear in mind, of course: the degree of uniqueness between two samples is determined by the metrics used to distinguish between them. I don't know the state-of-the-art with fingerprint analysis, but with a purely physical measure, how can fingerprints not be unique?

lmm 11y ago
At that kind of physical level every time the same individual is fingerprinted you get a slightly different result.
the_ancient 11y ago
I am saying there is no study to prove they are, thus one must assume they are not. Further there is not be a study to see if my left index may match your right middle finger, etc. I do not believe there is enough possible entropy for ~74 billion 100% unique never to be repeated patterns on finger prints... (7.4billion humans x 10 fingers per human)
dalke 11y ago
Many people have problem telling identical twins apart, so under that metric it's true that human faces aren't globally unique. There's even a project to find "twin strangers", which has had some success (see the images at the bottom of https://twinstrangers.net/ https://twinstrangers.net/ , though they also had the same makeup applied, which makes them look even closer). > how can fingerprints not be unique? How can the hash of two different strings be the same? It's all part of the Birthday Paradox, combined with that it means two identify two physical objects as the same thing. Now, at some point no two human-scale objects are the same. Even with two mass-produced objects, there are slight variations in production because of non-zero tolerances. For example, two sequential $1 bills differ of course by the serial number, but also contain minute differences in the paper. So as you say, we need to distinguish between how fingerprint analysis is done, vs. the most detailed possible analysis. And we know of several cases where fingerprint identification has been incorrect. One is Brandon Mayfield, a US attorney who the FBI believe, on the basis of a fingerprint match, to have been one of the Madrid bombers. As a result of that case, and similar ones, people have started to ask the police and others for data which shows that "all fingerprints are unique" is really true. This myth started over 100 years ago, but was based on a small sample size. There's never been the analysis needed to figure out the actual error rate, especially if there are, say, 100 million entries in the system. See also https://en.wikipedia.org/wiki/Fingerprint#Validity https://en.wikipedia.org/wiki/Fingerprint#Validity . And notice how that Wikipedia page also includes "No two fingerprints have ever been found identical in many billions of human and automated computer comparisons.[citation needed]". Where is that citation?
mobiuscog 11y ago
Probability is not a guarantee. Randomness does not guarantee uniqueness.