What's the science behind fingerprints?

[dstebbins]

Think about it: No other animal has them, not even apes, and even if some other animal DID have them, there's a trademark thing about fingerpints that doesn't make any sense form an evolutionary standpoint: No two people have the same fingerprints.

 

Think about it: They can help police catch criminals, and... that's about it. Mother Nature doesn't give a rat's arse about fingerprints; they serve no tangible benefit other than what humans do with them, so why would natural selection create them? Unless we're going to argue that God made them (which is a big no no with modern science, even if you believe in God), then we'd have to accept that, from an evolutionary standpoint, they're completely pointless.

 

Just about everything else about humans has a purpose, and it's completely understandable how cavemen with these traits would have an advantage. Opposable thumbs, walking upright, being able to study the world around and make tools to replicate those effects. Heck, even mankind's love for bloodshed (which we've tempered, but still cater to, through things like MMA and video games) is an understandable by-product of Darwinism, as in the times of cavemen, every day was kill-or-be-killed, so those who enjoyed it became better at it.

 

Fingerprints, on the other hand, served no purpose whatsoever for anything until mankind realized "Hey, nobody has the same fingerprints! NEAT-O!"

 

So... why do we have them?

[Fuzzwood]

It's random folding of skin. It helps us with gripping things by giving extra surface area, helping friction.

[granpa]

it keeps the layers of skin from sliding past one another and forming a blister

[Appolinaria]

Fingerprints develop in the womb from stress on the basal layer. It appears as though it is a byproduct of normal skin development. I don't see why it needs a purpose. I could be wrong here.

Edited June 26, 2012 by Appolinaria

[Ophiolite]

Think about it: No other animal has them, not even apes, and even if some other animal DID have them, there's a trademark thing about fingerpints that doesn't make any sense form an evolutionary standpoint: No two people have the same fingerprints.

Apes have fingerprints and these fingerprints display the same diversity seen in humans.

[swansont]

They aren't identical because it's random. Even identical twins do not share identical fingerprints.

 

Mother Nature doesn't give a rat's arse about fingerprints

 

Ironically, rats have assprints.

(If you give me a minute, there will be a wikipedia article on it…)

[Arete]

No other animal has them

Yeah they do:

 

One print is a chimp, one is a koala and one is human.

 

http://www.odec.ca/projects/2004/fren4j0/public_html/animal_fingerprints.htm

[swansont]

Yeah they do:

 

One print is a chimp, one is a koala and one is human.

 

http://www.odec.ca/projects/2004/fren4j0/public_html/animal_fingerprints.htm

 

Wondering why this hasn't come up on CSI yet. Maybe they're waiting for CSI:Sydney

[Appolinaria]

They don't have humans in Australia

[iNow]

Sorry to spoil the fun, folks... but fingerprints are not as unique as you've been taught to think.

 

http://www.pbs.org/wgbh/pages/frontline/criminal-justice/real-csi/forensic-tools-whats-reliable-and-whats-not-so-scientific/

 

For more than a century, fingerprints, palm prints and sole prints have been used as identification tools by law enforcement. Collectively known as “friction ridge analysis,” this forensic method involves examiners comparing the details of an unknown print with a set or a database of known prints. These details include ridges, loops, whorls and other points of similarities.

 

Criminologists and law enforcement officials long swore that fingerprint identification was infallible and that it was possible for an examiner to determine that a print comes from a single unambiguous source. If an examiner has a whole, perfect print, they argued, identifications can be made with reliability.

 

But recent errors have fueled a debate about the reliability of fingerprint forensic evidence, the most prominent being the case of Oregon lawyer Brandon Mayfield. After the March 2004 terrorist bombings in Madrid that killed almost 200 people, a partial print found on a bag of detonators was sent to the FBI. An examiner determined that the print belonged to Mayfield, who was later detained. In total, four fingerprint examiners – including one hired by Mayfield’s defense team – declared that his print matched the partial from Spain.

 

Except there was a problem: the print wasn’t Mayfield’s at all. Spanish officials matched the partial print to an Algerian man named Daoud Ouhnane.

 

<...>

 

According to the National Academies of Sciences, no peer reviewed scientific studies have ever been done to prove the basic assumption that every person’s fingerprint is unique. Recent studies have also shown that fingerprint examiners can be influenced by contextual bias when comparing fingerprints.

 

Here's an actual report summarizing the little actual science there is underlying forensic "science."

 

http://www.nap.edu/catalog.php?record_id=12589#description

[Appolinaria]

Sorry to spoil the fun, folks... but fingerprints are not as unique as you've been taught to think.

 

http://www.pbs.org/wgbh/pages/frontline/criminal-justice/real-csi/forensic-tools-whats-reliable-and-whats-not-so-scientific/

 

 

 

Here's an actual report summarizing the little actual science there is underlying forensic "science."

 

http://www.nap.edu/catalog.php?record_id=12589#description

 

Of course out of all the humans on the planet parts of our prints may resemble anothers and lead to problems as above but that doesn't mean each print isn't completely unique (which is what I was told).

[iNow]

Out of curiosity... Did you read what I shared before commenting?

[Appolinaria]

Out of curiosity... Did you read what I shared before commenting?

 

Yes, I did surprisingly. Here you're making the incorrect assumption that "fingerprints aren't as unique as we think". When if you read about the Mayfield case it was blatantly shotty work on the FBI's part, not fingerprints of two different people being virtually indistinguishable, that caused a wrong arrest.

 

"F.B.I. officials said that the erroneous fingerprint evidence against the lawyer, Brandon Mayfield, 37, of Aloha, Ore., stemmed from the poor quality of a digital image of the print sent from Spain and that they were conducting a review into the use of such procedures."

 

http://www.nytimes.com/2004/05/25/us/bomb-case-against-lawyer-is-rejected.html?ref=brandonmayfield

 

 

I don't see how problems with forensic science have anything to do with the actual makeup of fingerprints. Sounds off topic. Sorry.

Edited June 27, 2012 by Appolinaria

[iNow]

I think you took a different point away from my post than the one I intended to convey. The idea I was presenting was that if fingerprints were truly so unique, such mistakes in identification would not be so easy to make. Yet, they're quite common because finger prints are not as unique as we think. I actually watched the hour long special on which that short article was based, and perhaps that conveyed my intended point more completely than the synopsis I shared. I dunno... No worries.

 

Overall, the larger issue is that there tends to be surprisingly little science underlying forensic "science." A lot of it is based on little more basic tradition... a good 'ole boys approach equivalent to "this is how it's been done for years," and the practices continue even when empiricism does not support the technique as being effective, and even when no empiricism exists whatsoever... and yet that's what we're using as the foundation of so many profound and life altering/family destroying decisions in our courts.

 

To the OP... I think we have fingerprints because the texture helped us grip things better, and those who could better manipulate tools and instruments tended to do better in having successful offspring than those that were less able in the digit department.

Edited June 27, 2012 by iNow

[ecoli]

Overall, the larger issue is that there tends to be surprisingly little science underlying forensic "science." A lot of it is based on little more basic tradition... a good 'ole boys approach equivalent to "this is how it's been done for years," and the practices continue even when empiricism does not support the technique as being effective, and even when no empiricism exists whatsoever... and yet that's what we're using as the foundation of so many profound and life altering/family destroying decisions in our courts.

its getting there though: http://en.wikipedia.org/wiki/University_of_Tennessee_Anthropological_Research_Facility

 

To the OP... I think we have fingerprints because the texture helped us grip things better, and those who could better manipulate tools and instruments tended to do better in having successful offspring than those that were less able in the digit department.

And note that this would have been especially helpful for mammals lower on the evolutionary food chain, since most animals can't grip nearly as well as humans can.

[Appolinaria]

To the OP... I think we have fingerprints because the texture helped us grip things better, and those who could better manipulate tools and instruments tended to do better in having successful offspring than those that were less able in the digit department.

 

http://news.bbc.co.uk/2/hi/health/8093134.stm

[ecoli]

http://news.bbc.co.uk/2/hi/health/8093134.stm

 

Instead, Dr Ennos believes that fingerprints may have evolved to help us grip on to rough surfaces,

 

Study is not terribly convincing, given most animals never [have] come into contact with acryllic glass and the above hypothesis (which went untested... ?)

[hypervalent_iodine]

Study is not terribly convincing, given most animals never [have] come into contact with acryllic glass and the above hypothesis (which went untested... ?)

 

I was just about to quote that same excerpt. Seems strange that they wouldn't have tested it. The likelihood of encountering glass-like surfaces compared to rough surfaces in the natural environment seems like it should be much lower.

[Appolinaria]

Study is not terribly convincing, given most animals never [have] come into contact with acryllic glass and the above hypothesis (which went untested... ?)

 

They determined whether skin behaves more as a rubber-like or hard material, in terms of friction.

 

Surface area is a factor in rubber-like materials if I'm not mistaken. Ridges reduce surface area and therefore friction in rubber-like materials, so I don't see how even if the glass was swapped for bark this fact wouldn't still hold true.

Edited June 27, 2012 by Appolinaria

[swansont]

I think you took a different point away from my post than the one I intended to convey. The idea I was presenting was that if fingerprints were truly so unique, such mistakes in identification would not be so easy to make. Yet, they're quite common because finger prints are not as unique as we think.

 

Unique is kind of a binary state. Either something is unique or it isn't. There are degrees of similarity, but not of uniqueness; fingerprints can be quite similar and yet be unique.

 

Your critique is that of forensic analysis, not of the uniqueness of fingerprints.

[iNow]

They determined whether skin behaves more as a rubber-like or hard material, in terms of friction.

 

Surface area is a factor in rubber-like materials if I'm not mistaken. Ridges reduce surface area and therefore friction in rubber-like materials, so I don't see how even if the glass was swapped for bark this fact wouldn't still hold true.

Think of velcro. If velcro were smooth, it would not work. Since it's rough, the little hooks allow it to grip much better. The same process applies in nature.

 

We evolved to grasp rough surfaces, and certainly not glassy smooth ones. Those rough surfaces were better gripped by hands that also had ridges and roughness, as the valleys and peaks are what allowed greater manipulation. A smooth hand would slip off the spear or the rock more easily. My reply aligns with ecoli and hypervalent.

 

As I see it, the flaw in the study you cite is in the use of glass as the test surface, so while it's an interesting finding it doesn't really apply in this context or in this discussion we're having. We were talking about fingerprints evolving, and potentially because they increased grip-ability. Citing the fact that the ridges DECREASE grip-ability on glass is quite moot, since those same ridges IMPROVE grip-ability on rough non-smooth surfaces.

[iNow]

Your critique is that of forensic analysis, not of the uniqueness of fingerprints.

Indeed, you are quite correct. I was rather sloppy with that point. I would personally like to find better evidence supporting the uniqueness of fingerprints, and whether or not they are as distinct as we currently think, but until that happens I stipulate that my previous comments were tangential to that topic and focused mistakenly on forensic "science" as a whole. Thanks for correcting me.

[Joatmon]

They determined whether skin behaves more as a rubber-like or hard material, in terms of friction.

 

Surface area is a factor in rubber-like materials if I'm not mistaken. Ridges reduce surface area and therefore friction in rubber-like materials, so I don't see how even if the glass was swapped for bark this fact wouldn't still hold true.

 

This begs the question "Why is it illegal to have bald, i.e. smooth, car tyres? I imagine that it is because a smooth tyre will slip more easily on a moist surface although it might offer more grip on a dry surface. Perhaps most things a primitive human needed to grip was likely to be moist in some way. Some things I can think of are moist branches to be climbed and even blood on some killed or wounded animal. Before posting I've had a quick Google round and I see that chimpanzees and apes also have fingerprints which suggests they offer some evolutionary benefit.

[Arete]

This begs the question "Why is it illegal to have bald, i.e. smooth, car tyres? I imagine that it is because a smooth tyre will slip more easily on a moist surface although it might offer more grip on a dry surface.

 

Racing slicks are bald for this very reason. Whilst you undoubtedly get more traction by increasing the contact patch in the dry, If you give water under the patch nowhere to go and subsequently end up driving around on a fine layer of water, it's quite the opposite effect in the rain.

 

Having driven in the wet on drag radials, I can tell you first hand that when changing direction or velocity it's quite easy to wind up with the driver's seat pointing the opposite direction to the one the car is traveling in - quite the sphincter clenching experience if there is anything nearby to potentially crash into.

[Appolinaria]

This begs the question "Why is it illegal to have bald, i.e. smooth, car tyres? I imagine that it is because a smooth tyre will slip more easily on a moist surface although it might offer more grip on a dry surface. Perhaps most things a primitive human needed to grip was likely to be moist in some way. Some things I can think of are moist branches to be climbed and even blood on some killed or wounded animal. Before posting I've had a quick Google round and I see that chimpanzees and apes also have fingerprints which suggests they offer some evolutionary benefit.

 

Aiding in channeling water makes sense but concluding that fingerprints must have an evolutionary benefit because chimps and apes have them doesn't make much sense to me- are you implying they developed separately in each species?

 

Why must everything always be beneficial? Can't we be caught in the in-between of something vestigial from a common ancestor being weeded out? Can something be neutral and not expend much energy so it kind of lingers for a while?

Edited June 30, 2012 by Appolinaria