What is the evolutionary significance of unique fingerprints

Most things in nature happen for a reason. So why did we develop individually unique finger print patterns. Whats the dope on it?

THe reason we have fingerprints, or palmprints or footprints or toe prints for that matter is most likely due to an increased ability to grip rough textures, partially in wet conditions (the crevices and folds in the skin helps drain away water). However, there is noe advantage to having (a high probability of) unique fingerprints. It’s just random folds of the skin. The gentic code for creating the skinpatterns have virtually a infinte amount of variations to “chose” from, so from that randomness the odds of two peopla getting the exact same folds and patterns is slim.

Actually, things in nature don’t happen for a reason. Often they find a purpose, but often the adaptation precedes the niche. Wings came before flight, for example. They were eventually used for the purpose of flight, but didn’t show up just for that reason. And aren’t even always used for that. Penguin wings are used to propel them through water, like dolphin flippers.

Fingerprints are unique probably because people are unique. It would take an awful lot of effort and energy to make everyone’s fingerprints the same.

There’s some genetic influence over fingerprint development, in that certain types seem to be dominant, and identical twins always have very similar fingerprints. But development in utero influences fingerprints. I know someone whose dissertation was about the influence of stress on a fetus and fingerprint development. It seems that certain kinds of pregnancy events tend to produce fingerprint characteristics. And often in a twin pregnancy, one twin experiences more stress than the other, so that would cause their fingerprints to be different, even if they were genetically programmed to be the same.

It would take a lot of investment in energy for people to have the same fingerprints, and that is a lot of investment in a trivial thing. Biology doesn’t waste energy on trivial things. It’s why we don’t have four eyes and the sense of smell of dogs. We don’t need them, so we don’t have them.

The fact that having unique fingerprints is useful in law enforcement is a coincidence. It’s a lucky one (if you aren’t a criminal), but it’s merely taking advantage of a fact of nature, just like using vaccines to avoid having actual illnesses is taking advantage of the way our immune systems work.

Perhaps they coevolved with CSI detectives.

The serious answer is what abel29a said. Not all evolved traits are adaptive. The roughness created by the fingerprints was probably adaptive for gripping; but the uniqueness was probably just an accident of evolutionary history and not selected.

It’s not necessarily true that “most things in nature happen for a reason”. Many do, many don’t.

We also have unique toe prints, irises, retinas, and so on. The really important answer is above - we have different fingerprints because there is no advantage in having identical ones.

If we had identical ones there would need to be genetic coding for the identical prints, rather than a generic formula that generates fingerprints with no direction other than that they be fingerprint like. Those genes would need to be conserved, which takes a lot of work (where work is a rather abstract thing here, but it isn’t trivial.)

Since there is no advantage in identical fingerprints, none of the above is selected for, and doesn’t happen.

If you look at animal patterning you see a similar thing. In the abstract all zebra’s are pretty much alike - but in reality none have exactly the same pattering. The patterning is controlled by only a few parameters (rather interestingly largely worked out by Alan Turing) and then simple random variations in the precise parameters yields the variation. Indeed, it would appear that any animal pattering from cat stripes to pandas, giraffes and so on are all so controlled. I suspect the fingerprint generation processes are rather similar. Overall general form is coded for, but detail is in-utero variation.

Yeah, my understanding of the way evolution/natural selection works is that things in nature don’t happen for a reason: they happen randomly, but then they survive for a reason, the reason being that they somehow help an organism to not die and/or to reproduce, or at least don’t interfere with those things.

Right. There is no more reason for fingerprints to be identical than for snowflakes to be identical.

Fingerprints, like many other things that have been mentioned, have a general genetic code that generates them. However, the precise details aren’t important to their function. Therefore they are free to vary depending on minor influences during development. They are useful for identification because they are complex enough for development to produce almost infinite variations.

Who say’s they are unique?

Too late to add: Check out this episode of Frontline, starting at about 5:07.

I think this may be a little pedantic, depending on the audience. I certainly agree that it’s important to emphasize Darwin’s key insight that the process of evolution is the origin of novelty solely through random mutation, with an appearance of purposeful design arising from natural selection among random variation. Still, it’s routine shorthand among biologists when discussing an adaptive trait to say “this evolved because…”.

Note that a random-ish pattern helps improve the gripping power. Having all the folds run in one direction, for example, won’t work as well. Now, the way the fingertips are generated limits the pattern quite a bit, hence the loop/whorl basis. But having a bit of random deviation from the simplest pattern is a good thing. Randomness increases the chance of uniqueness.

There are several “patterns” in nature that are a basic outline permuted a bit in individuals. E.g., zebra stripes. But they’re still arguing over why zebras have stripes at all, never mind why they vary. Evolution doesn’t care if we understand it or not.

This is one of those things I don’t get about evolution. Sure, fingerprints are more grippy than smooth tips but in the natural world that they evolved in I just can’t seeing it making that big of a difference.

Bark is much rougher that fingertips. Rocks (in general) are much rougher too. I’m not saying print folds aren’t better, I just can’t imagine a situation where a fingerprinted ancestor would survive catastrophe (to pass along those genes) and a smooth padded ancestor would not. And it had to happen over and over and over…

It’s much easier for prosecutors to obtain convictions if everyone is convinced that they are unique. Humans don’t handle very low probability scenarios like matching fingerprints well, so many people assume uniqueness, even when there’s evidence to the contrary.

A couple of comments:

(1) It may not be “grippiness”, it may increase surface area to improve sensation, or other possibilities we haven’t thought of. It’s quite difficult to do experiments to test hypotheses about small fitness advantages in the ancestral environment.

(2) It may not be adaptive, it may be an accident of evolution.

(3) Our intuition for the immense scale of geologic/evolutionary time is poor, as is our intution for compounding over such long periods. Suppose that a human with fingerprints had a survival advantage of just 0.1% over a lifetime:
0.1% compounded over 1000 generations = 270%.
0.1% compounded over 10,000 generations = 22,000%.
The mathematics of compounding shows how even tiny fitness differences can take traits to fixation rather quickly over evolutionary time.

What he became famous for was his idea of Natural Selection: the application of English upper class ideas about breeding to the question of the origin of species.

Reading from his famous book, he was open to the idea of Lamarckian inheritance as the source of variance.

I really wish we could somehow sticky this and just respond to every question about “Why didn’t humans evolve ; it would make them SO much better!” with a link.

“Grippyness” as a feature of skin is more likely a result of some distant ancestor than something that evolved in humans. I would expect that lemur-like early mammals needed grippy “fingers” and that we inherited them because there’s no reason for us not to.

It’s likely that fingerprints go back at least to early primates, because modern apes, monkeys and humans have fingerprints. Lemurs apparently do not, so they may have evolved somewhere between lemurs and the earliest common ancestor of the modern monkeys and apes (and humans)

It could also just be a random side effect of some other process going on, such as how the cells that grow the fingerprints figure out where they are supposed to be or how they divide after they get there. Or something left over from past ancestors. If it’s not actively bad for the animal, it will be retained.

One thing to keep in mind is that it doesn’t take many independent features to make it very likely that there will be no repetitions. If you have 31 independent yes/no features (ridge here, swirl there, etc.) then there are about 2 billion possibilities. It’s the same idea as tossing a fair coin x number of times. Throw in a few more variations and you have many times more possibilities than the planet has people.