how was it proved that every person has unique fingerprints?
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It never really was. It started off being used by the FBI to help solve cases scientifically back in the 20th century. Over time it became an acceptable standard of uniqueness. But at the time it would have been impossible to prove they are really unique since computers werent invented yet.
Not sure anyone has actually proven uniqueness in the age of computers. Maybe they have.
Not the guy with the answer, but I will point out that “proved” is an absurdly strong standard to meet, one that science is not interested in. As far as we know, there’s nothing preventing the exact same fingerprint to appear again, as long as the conditions for it are met. It’s just that those conditions are really specific, so we humans won’t be able to replicate it intentionally, at least not yet.
It has in a way been disproved, as I understand it, is it only possible to determine with a margin of 1 in 50. It does also turn out that people’s fingerprint can change over time, by damage and other thing, such that a child’s print can differ from the adults.
It is the same as bite marks that previously were considered evidence, now are considered only circumstantial.
It wasn’t! Cops just started saying that. Same with the idea that a person’s fingerprints stay the same for their whole life. It turns out a lot of forensic science is just “well, no one’s proved it wrong yet.”
It isn’t proven. It’s simply *wildly unlikely* that a randomized, complex, detailed pattern is going to turn out the same for multiple people.
For example, say your phone unlocks with your fingerprint. There might be someone out there, somewhere, with fingerprints that *just happen* to match the same dozen spots that your phone checks. But the odds that this person exists somewhere *and they’re trying to get into your specific phone* are effectively 0%.
Forensic fingerprint “evidence” is increasingly less creditable for the reasons you pinpoint. It’s certainly not as reliable as DNA, for instance.
TIL that it is not true that every person has a unique fingerprint.
Wow.
If I recall correctly, fingerprints are formed in utero from a fetus touching its surroundings. So the variables that go into the formation would likely be very difficult to replicate. Even identical twins have different prints.
Unless every single person’s fingerprint can be obtained, loaded into a single database and analyzed for comparison, it can’t really be proven that every fingerprint is unique.
That said, I don’t believe there’s ever been a documented case of any 2 people’s fingerprints matching on all of the unique markers that are measured. Fingerprints are formed in the womb and while genetics plays a role in their formation, other variables such as pressure in the womb, the fetus’ location and position in the womb, and the way the amniotic fluid runs across the fingers. It’s takes roughly 5 months for fingerprints to fully develop.
So you can think of fingerprints forming along the same lines of how a river or stream would form. Every flowing body of water in the world has carved out its path in a completely unique pattern because the conditions surrounding them (environment, altitude, temperature, etc etc) is never identical.
But the best example I can think of to “most proove” the uniqueness of fingerprints is that even identical twins don’t have matching prints, which can be more telling than even a standard DNA test when it comes to differentiating between identical twins. Even in the same womb, the conditions surrounding the fingers of each fetus aren’t identical.
You can’t prove that something doesn’t exist. I challenge you to prove that satanist unicorns don’t exist. You searched them really hard and don’t find them ? Search harder, you might have missed it.
When you test a hypothesis hard enough, you can affirm that it seems to be quite close to the reality, your hypothesis just became a theory. That means that until proved wrong, unicorns don’t exist.
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