Human Finger Prints

[Bazile]

Given the number of people who have come and gone , and those that remain - can it be correct that all has / had a different finger print

[jim360]

Yes.

[Old_Geezer]

I don't think there is any particular reason why each has to be unique (especially as measurement is non perfect anyway) but there is so much possible variation the chances of finding a matching pair must be astronomical.

[jim360]

I suppose really I should expand on that, but I was aiming for brevity for a change.

It's generally thought that fingerprints are unique, although there is no proof of this as far as I can tell, and probably never will be. All the same, the large number of human individuals isn't evidence against the idea: 7 billion now, maybe 100-odd billion in total so far, is actually a tiny number in the grand scheme of uniqueness, and barely comes close to exhausting the potential number of distinct fingerprints.

On the other hand (no pun intended), the traces left behind by fingerprints aren't necessarily unique, can be subject to interpretation, aren't perfect representations of the fingertip, etc etc. Apparently some studies have shown that experts on fingerprints can disagree with each other about whether this fingerprint is a match to that one, and even disagree with themselves when shown the same fingerprint twice. So there is some subtlety in this, as always.

See also http://www.telegraph.co.uk/science/2016/03/14/why-your-fingerprints-may-not-be-unique/ (although here fingerprints ought to be read as "marks left behind by your finger"), and https://www.scienceabc.com/innovation/why-are-fingerprints-unique-and-why-do-we-have-them.html

[woofgang]

if snowflakes can be unique...and DNA....then why not fingerprints?

[jno]

identical twins have the same DNA, but apparently not the same fingerprints.

[atalanta]

Even if you could find two people who started life with ( some ) matching fingerprints, scratches/scrapes/scars and wrinkles would soon leave different permanent marks on top of the original whorls and swirls. By the time people were old enough to commit a crime, the fingerprints would be seen to be clearly different from one another.

[Peter Pedant]

well theyre not unique
identical twins have the same ones dont they

what intrigues me is how the DNA specifies identical ( erm random ) patterns

[Peter Pedant]

jno - we have twins in the family
and one thumbprint can activate the others phone....

caused a certain amount of consternation as for 71 years everyone thought they were brothers ...

[jim360]

"what intrigues me is how the DNA specifies identical ( erm random ) patterns"

I believe the answer to that is (thought to be) that it doesn't, and that the patterns on fingerprints are, at least partly, a response to conditions in the womb. This would at least explain why identical twins with identical DNA don't share fingerprints; and also provides a reason for the seemingly infinite variation. The conditions in which fingerprints form are almost certainly never going to be exactly the same.

[jomifl]

Identical twins aren't identical, their blood vessels and innervation are different as a result of a slightly different environment. The same must apply to fingerprints.