Why Fingerprints?

to explain what these are. You have these fingers, you're blows right at the end of each one, you find these curious designs, little trenches and whirls forms, this little pattern, and uh, from a very early age, we all know that these signify who we are. Right, put it in an ink, put it on a page. There's your fingerprint. It's a part of like kindergarten art classes. You know, you make a turkey with your hand. That turkey is a is a blueprint of who were, not real blueprint,

but it is a signature of who you are. No one's Thanksgiving handpay turkey is the same as another individual's Thanksgiving hand paint turkey. They're unique and really they should be what we should use, in my opinion, as signatures on all official documents. You think, yeah, it's you know, just with the turkey design is in specific Yes, yeah, like Kofe anon Um, Barack Obama, Vladimir Putin, I don't

care who they make an official document. At the bottom of it, they've put their hand down with paint and then trace around it and then make a Thanksgiving turkey. Well, and of course you're bringing this up because it's thought that the fingerprint is unique to this unique biometric that we've got, nobody else has it. And uh, that's one of the things we're gonna get in today, that the fingerprint as an identification tool. And we were generally that's

where our minds go when you talk about fingerprints. You think of C. S I and all this stuff, and they know their prints left here, Prince left there, and those prints that the police are supposedly going to collect and solve a crime with. But we often overlook the underlying question why do we have them? To begin with? What are they right? And we're going to discuss at as well fingerprints the why of fingerprints from various standpoints.

That's the episode today. Well, here's the deal. Many mammals have them, but humans are the only ones to have really complex patterning. And there's a general flow to fingerprints, UM, especially to what we call the ridges that translate into one of three major pattern types. So we're talking about a whirl, a loop, or an arch. And it's possible to have just one, two, or all three pattern types

among your ten fingers. And here's a little tidbit about that six of the world's population has loops, five percent, only five percent of the world world's population has arches, and thirty five percent of the world's population has whorls. Yes, and I can tell you that I've already detected a couple of whorls on my fingertips. But why why do we have these fingerprints? Well, one theory why why, Robert,

why are we cursed with these things? Well when one reason that is often brought up and theorized about, uh, and certainly it makes it seems to make a lot of sense on the surface of things, is that we use them for grip. It's like, because you look at it, it's like it's like you got some ridges there, and I think of like gloves that are made for gripping things, and they tend to have some sort of a ridgid ridge ridge based surface there, weightlifting gloves, weight lifting gloves,

things like that. So maybe we have them to lift them. Maybe it's so that if we're picking up a glass of milk or swinging a battle axe, whatever you need to grip the groove. Prints improve the friction rate between finger and object. But not so, according to a team of researchers at the University of Manchester, they looked into this make on the whole idea is just a bunch

of hooey. There's a two thousand nine study Journal of Experimental Biology, and the menu team measured the friction rate between flesh and objects can discovered only a marginal increase. They also discovered that printed finger pads actually come into contact with an acriolic class already three less than completely smooth finger pads, and in some cases the prints actually reduce our grip rather than improve it. Okay, so that

is out. We don't eat them for grip. Yeah, okay, So there are a couple other theories um in play here, and maybe that they allow our skin to stretch and to form more easily, protecting it from damage. Yeah. The idea here. I like to think of men's slacks, like, what are the least style of slacks a guy can wear? Big balloon Khaki's right it's like a big balloon crotch that anytime you sit down it looks like, um, some sort of like automobile protection device has gone off in

your pants. Yes, it is. That's balloon balloon crotch in khaki pants. And I used to have to wear khaki pants to my job at a newspaper, and so that I was always having to deal with that, and it's awful. But I'm pretty if your pants are that baggy, you're pretty much guaranteed not to rip them, right, It's kind of like yoga pants or hammer pants. There's a lot of room to move around, you're not gonna rip them.

But if you're wearing say some nice stylish skinny jeans, some like really narrow drain pipes, and you try and do anything, Heaven forbid, you try and do the splits, or even bend over and pick something up, you're gonna tear something. Hopefully you'll tear the pants. But but I like to think then of this theory is that the fingerprints are rigid. Fingerprints are kind of the uh, the

balloon pants, the hammer pants of skin. Okay, so those ridges are kind of like the hammer pants, and that they could expand and deform onun will if they need. There's also this idea that fingerprints may allow water trap between our finger pads and the surface to drain away and improve surface contact in wet conditions. Kind of makes sense, right, Other researchers have suggested that the ridges could increase our

finger pads touch sensitivity. Yeah, that's a really cool one. Uh. And this is the the idea that when you're you're feeling particularly fine features, such as a single human hair on a desktop, your sense of touch depends on skin vibrations that arise as your fingertip moves across the desk.

So when two thousand nine, a team of French researchers looked into this, and they found that a rigid fingertip moving across the surface produces vibration frequencies that are detected by special nerve endings called Bassinian corpuscles, and these nerve endings then passed this information onto sensory neurons that signal

the brain. So the idea here is those without those ridges, if you burn them off with battery acids so that you can commend more crimes or what have you, you would not be able to feel as as as easily you would not be able to feel those tiny fine details and things, which is really cool. Yeah, so here's this idea. Can you be born without them? Here's this question?

You can? You can? You really well do explain. This was discovered when a twenty nine year old Swiss woman of the U. S Border was made to wait for hours as puzzled officers tried to make sense of her missing prints, and as a result, this has been dubbed the immigration delay disease. I kuld you not really. It's very very rare and has only been documented in four families across the world. So they had no prints. They

had no prints. Yeah, so you could argue they had identical prints then since that the prints that they had were non existent. Question. Yeah, I was gonna say, it's maybe a different question. But genetically it is able. It's possible for you to be born without prints. Again, very rare, and I think that the calling it a disease is even kind of a bit specious because it's like, well, you know what, what was the problem other than not having maybe you can't feel very fine surfaces. Well, see

that's that's the only thing they say. Typically, the pores of sweat glands lie along the tiny ridges that make up our fingerprints. So for people with this mutation, the ridges don't even form to begin with interfering with sweat glands, okay, and as a result people actually they sweat less on

their hands, so the body makes up for it. Now you can get rid of them, your fingerprints, if you've ever wondered um that some people have gone to some crazy links to do so, but repeat exposure to some chemicals can can remove them or modify them as well as callouses. So if you're doing a certain type of work, you could actually have your fingerprints pretty much smear to nothing, or the traditional method in crime family just to let

a turtle chew them off. You put a little you smear a little meat paste on each on each of your fingerprints, preferably a baby box turtle or a pack of them, and then you let them chew on the fingertips until you're satisfied, and then you get to get This is the Paliocci crime family method. Yeah, well, okay. In the nineties, kidnapper Theodore Handsome Jack Clutus took a knife to his fingerprints, and that was the first documented case of finger mutilation. And then the notorious bank robber

John Dillinger dipped his fingers in acid. Obviously that's the somehow that sound like a in wins at that one, like with the slicing, but are actually pretty terrible, right, But somehow the burning of the prints off seems not so crazy, but surely it hurts. Well. I guess the thing is we can relate. Everyone has cut their fingers, or most of us, I feel like they've cut their their fingers one there, like peeling potatoes or something, so we have a frame of reference for that, whereas being

scalded by battery acid and maybe not so much. I just feel like if you're going to cut the fingerprints off of your hands, that you're already bringing more attention to your fingers anyway. So we were like, hey, why why why do you have cut fingertips? Oh? I don't know, no reason. And then you know, of course in that day and age are probably like, that's the dude with the strange missing fingertips. Do you think something's up with him? Yeah?

I don't know. It just any kind of self inflicted flame, whatever your purpose, it's just weird. I'm just saying it's not subtle. I did just think it was a bad way to go, all right, So how do finger prints form in the first place. Well, it's it's it's interesting because it's not something we are, it's not in our genes. It's not necessarily genetic thing really going on here. This

is something that forms in the womb. And what happens is, uh, the outer epidermist and the inner subcutaneous tissue sandwich the dermal cell layer between them, like a slice of cheese between two slabs of bread, and as the pressure builds, the slice of cheese again, that's the dermal cell layer compresses in buckles, erupting into random surface patterns. I love that. Yeah, yeah, And I wanted to give some more detail on that too, because some of how that's done actually influences the pattern

that you get. Um, we have these friction ridge skin covering the surface of our hands, and that's what comprises the ridges and the furrows. So, as you say, in those um, during those weeks I think it's ten through fifteen weeks, the fetus develops smooth vallor pads. These are raised pads, and the fingers, poems and feet because of swelling mess and kimmeled tissue, which is a precursor for

blood usseles and connective tissues. And then around week ten, the volor pads stop growing, but the hand continues to grow, and then as a result, over the next few weeks, the volor pad is absorbed back into the hand. This is what you're talking about, um. During this stage, the first signs of the ridges begin to appear, and the spacing and arrangement of these early ridges is a random process, but it's dictated by the overall geometry and the topography

of the volar pad. So if the ridges appear while the volar pad is still uh quite pronounced, and the individual will develop a world pattern. And then if the primary ridges appear while the volar pad is less pronounced than the person will get a loop pattern on their fingers. And then if finally in the if the primary ridges appear while the volor pad is nearly absorbed, then the

individual will develop an arch pattern. And I love how they talk about it is topography because it really does kind of remind me of the only the Earth's own surface and the various elements going on to create causes mountains to rise and valleys to deepen. Yeah, yeah, and this is going on in the womb. It's so cool. So could one Olsen twin frame the other for murder? No? No, no fingerprints No, because even the Olsen twins, as identical

as they are, they do not have the same fingertip patterns. Now, they may have similar patterns because the patterns that you do get are genetic, but they will have a unique marker in theirs. So it's kind of like if one twin were slapped in the face by the same person in the exact same way, they still wouldn't get the exact same bruise on their face, necessarily because it's something that's being done to the twin rather than something that's

purely emerging from their genetics. That's right, Yes, all right, We're gonna take a quick break, and when we return, we will get into this idea of fingerprints is identification. To what extent is this a fabulous the idea to what extent is that deeply flawed? All right, we're back before we start talking about how unique fingerprints are and

bringing that into question. You know, I didn't want to mention that ridge characteristics may indicate genetic predisposition of certain diseases, and the Centers for Disease Control and Prevention actually performed research in two thousand and five that investigated these rich characteristics as a genetic roadmap for the predisposition of certain diseases. In particular, people with diabetes found UH. They found actually that these people have a much higher ridge count than

those with normal glucose tolerance. So it's kind of interesting that that they actually do tell us something just nonsense that happens. It's not like a nonsense password that doesn't mean anything in and of itself, but is unique well, and I kind of think of palm ream reading in this Sensemancy, if you want to get fancy well truromancy, it is uh, and that you could be able to

tell something about yourself through these fingerprint patterns. So the idea that a fingerprint is unique and could be used as a biometric, They could be used as something on our body that identifies who we are. The idea itself, you find this an ancient Japanese and Chinese civilization. They recognized pretty early on that this is something that's unique and we can use this essentially to put our signature on things. But for the most part, in the modern world,

especially in the Western world. It goes back to Sir Francis Galton nineteenth century. Polly Math is one of these guys by poly math of corpse of meaning. He was into everything. He was just a learned man who love to experiment, love to read about things, research things, and figure out how the world worked. And uh, you know it wasn't necessarily a specialist in any particular field, but just was ready to just go all in on whatever he was studying. And he was also the cousin of

Charles Darwin. Incidentally ran in the family. Yeah, ran in the family. I guess the brilliance and all. But he's the one who really pushed this idea that fingerprints are such a unique identifier and then they're a great biometric and that the idea of two individuals possessing the same fingerprint were so slim that it was virtually flawless. I believe he said that the chances of two people and

this was this was his math. Uh, the chances of two people possessing a matching fingerprint were one in sixty billion, which back then would have seemed pretty reasonable, right in terms of the chances of someone else possessing the same fingertips, and so that was a good case to try to use this as a biometric right, but what does that mean today? Like, just just on on the math level,

it's interesting. There's a guy. There's a fingerprinting expert, Professor Edward im Winkle Reed, which is a great last name. My own science editor Alison louder Milk, who also has a great last name, she kept emailing me back responding about this guy's name. She's like, oh my god, this is the greatest name I've ever heard, because it's there's a little it sounds like he should be abducted by by little people. There's a little bit of rumple still say,

it sounds a bit of a children's story name. Yeah, but as much as we we love his last name, uh in Winkle Read is a fingerprinting expert, and he argues that since world population now exceeds six point four billion and most of us possess ten digits, we have more than sixty four billion prints out there to bump the odds of having any two individuals share a single print. Well, she argues it's just one of the reasons why multiple fingerprints are important, and that we really need to consider

reforming fingerprinting as a biometric. That's one of his big causes, or has been over the last several years, is that we really need to rethink how much we can trust fingerprints as an identified her So, okay, then that problem actually would become more pronounced as more people come online. Right, so we've talked about adding the three point billion people by the year, so that we will now be nine

point five billion people. Yeah, but even when you if you disregard that as just pure number high jinks, you still get down to the question why did we buy Why did we buy into this idea that that that fingerprints are are so perfect? And according to statisticians Stephen M. Stigler, uh twentieth century reliance on fingerprints had less to do with science and reliability and more to do with courtroom drama and a fortunate lack of pattern repetition in prints.

So the argument here is that, all right, you have a trial going on that fingerprint. It looks really cool up there on the screen. For the most part, if all things created equal, it's pretty reliable. And I mean it's as we'll discuss here, there there's a lot of reliable things about the fingerprint. It's still pretty unique, but

it's not flawless. In fact, since evaluations of fingerprinting labs by collaborative testing services UH, those evaluations have discovered fingerprinting error rates ranging from three to So when you get into regardless of how how much you can trust fingerprintings, you get into the flawed potentially flawed nature of human fingerprinting biometrics and how we record them and keep track of them, interpret them, and then press charges with them,

you can get into like upwards failure rate, chance that you're gonna have flawed results. That gets pretty big, I mean, and that's why if you look at some of the rather lofty figures, I think it's like three and one. We're up to as of this recording, three one individuals cleared by the Innocence Project, individuals who had been convicted largely based on based on a number of things, but fingerprinting is a part of that, and then they were

exonerated via DNA evidence. Well, you know, previous to it seemed like the gold standard, and it's you know, historically between nineteen nine five and now, there really hasn't been that much time that has passed, so obviously a lot more reform needs to happen, especially when you consider um that you know this was this was the way that they began to identify criminals in the nineteenth century and

that was really helpful technology then, right. And I wanted to mention too that that this has its beginnings in eighteen fifty eight when an Englishman named Sir William Herschel was working at this the chief magistrate at the Hookley District in Singapore, India, and in order to reduce fraud, he had the residents record their fingerprints when signing business documents. So again that has a pretty big tradition back in

Japanese culture as well and before that. But as you said, this is a This is such a dramatic way to I d someone and to say this is the person that you can see how it's been in use for so long. But now, of course we are in a different age where we have so many different biometrics to

work with. Yeah, and people like in Winkle Reed and the Staggler, they're not they're not arguing that we should just abandon fingerprints, but rather that we should become smarter about how we used them and we should not depend on him as a soul biometric. However, that again, fingerprints are great and they can be very useful, and I think it's really interesting to how useful fingerprints can be not only immediately after death, but after a certain amount

of decay has occurred. I found this interesting BBC news story that interviewed Alan Bale, who is the author of the UK's standard police manual on dead hands, which is some great expertise there. And this is also something that you'll find you'll find in the US and other countries forensics manuals. So when he goes to cocktail parties to see, say I'm an expert on dead hands, I hope so I hope he does, because these are great. This is the kind of stuff I'm gonna have to share the

next cocktail pate party I go to. Because he talks about how, quote, if a hand is found in the water, you will see that the epidermist starts to come away from the dermist like a glove. This sounds gruesome, but if a hand has been badly damaged, I cut the epidermis off and put my own hand inside that glove. And by glove he means the flesh off that hand.

And then try to fingerprint it like that. So even though the outer layer of your head, of your the flesh in your hand has come off like a glove, like a loose glove, from the rotting remnants of the rest of your hand, this guy and other friends it professionals can then come along and just slip their own hand into your flesh glove and start rolling some prints out. They'll just buffalo bill of that. They'll just game's gum

that bet Yeah. All right, um, that's comforting. That's really comforting. Well, all right, let's talk a little bit about the future of fingerprints, because I found this really interesting. Um. There's a Huntsville, Alabama company called i Dare, and it has developed a system that can scan and identify a fingerprint from about twenty ft away, and coupled with other biometrics, it could soon allow security systems to grant or deny access from a distance without requiring users to stop and

scan a fingerprint or swipe an I d card. Now, the aren't customer for this is the military, but it has possibilities obviously in the marketplace and in fact as being beta tested in a gym right now. But the hope by the maker is that they can merge this technology with financial data, so you could simply scan your fingerprint rather than relying on credit card data and an r F I D chip or a credit card itself. Yeah,

that would that would be great. I've I've undergone a fair amount of fingerprinting lightly and it is even even in the when you're not using the the actual ink, when you're using the scanning method, it's still it's quite

an ordeal to go. But my mind instantly goes to RoboCop with this, because I can imagine RoboCop arriving on the scene holding out the gun, making the perpetrators put their hands up, and then in that instant instantly scanning their fingerprints and getting and checking the database to see if they match up with known perpetrators or wanted. I mean this, this kind of technology just kind of goes wild with your mind, doesn't it, because you can just

imagine all sorts of implicate sations on that. I also wanted to mention ears this is the new fingerprints, Yeah, because we know we have other biometrics. We have UM voice fingerprints D and a fingerprints IRUs and retinal scans. Yeah, and like retinal scans, especially that's been used to death and sci fi and and even non sci fi just slightly futuristic stuff on TV. So we get that we we were already this hammered into our minds that retinal scans would be useful. But the ear thing that caught

me by surprise. But when you when when I read it, I'm like, well, obviously, yeah, everyone's ear is going to be a little different. But I never thought of it as a biometric, a true biometric before. Yeah, because when you're born, that's the ear you get, right, you know, doesn't change much other than length or things that you do to it. Do you get to like some piercing?

I mean, that's the thing. The ear is one obviously not the most commonly mutilated parts of the human body well and also grown right under the skin of the arm. Was the woman who had the tissue for her ear that she grew under her arms. I don't know that you're not thinking of the artist though, No, I'm thinking about something else. Uh anyway, scrap that. The point is is that there are biometrics that are geared towards the ear,

And this is from Wired Science from Dave Mosher. He says, that a new shape finding algorithm called image ray transform, which boasts six percent accuracy according to a study by the i E Fourth International Conference, UH could use the outer ear to identify people. And it works by unleashing a ray producing algorithm on an image to seek out

curved features. And when a ray finds, when the software draws over the part and repeats the analysis, and in a few hundred or a thousand cycles, that cleanly paints the ear more than any other face structure. Of course, there are palms here which I think you've already idicated earmuffs all all with no idea who they were. Well, what happens to you when you when you get older the cartage, Yes, your ears fall off because the cartilage in your ear begins to stretch right, or you get

a bunch of piercings or tribal things. You know. Well, that's the other limitations of the system, because you could have also have hair covering in the ears. Again, as you get older, there's less than ideal lighting conditions. And then the big one is the different I D s generated from different angles that it's taken from. So there you have it fingerprints what they are? Why we have them, how we use them to I D people and single

out our uniqueness among so many other humans. Hopefully we got to give you a little more food for thought. The next time you're you're rolling that print around in some ink, or yeah, if you're getting booked, you know, take a take a moment just to see what sort of pattern you have. Yeah, or if you're you're eating some pudding, just take a moment to roll it around in there and then go up to a nice white wall and just stick it pudding. Yeah, all right, Yeah,

preferably chocolate. That's gonna show up better than yeah, you're vanilla or butterscotch. Okay, let's call the robe it over and do a little listener mail before we head out. This first one comes to us from Camilla. Camilla writes to us on Facebook and says, Hi, guys, let me start my message with an obligatory ego massage. Your podcast is awesome. I listened to it in the gym and my friends always think it's strange that I burst out

laughing while running. Thanks for that. And you know, we just did an episode on laughter and yeah, an exercise, so yes, if you are laughing while running, they may think it's weird, but you were getting you might be getting a better exercise and a more healthy exercise than they are. So let's doorphins are going to the roof. Yeah, every time we we say something funny. Uh So anyway, she continues, thanks for that. After your three podcasts on maps,

I couldn't help but feeling frustrated. I think the the area of my brain is broken. Seriously, every time I come out of a shop, I have no idea which direction I came from and where I should go. I'm a little better when reading maps, but creating mental maps seems just near impossible. Anyway, I'm sure you've got many messages about people and or animals with excellent sense of direction, and I thought I'd share the other end of the spectrum. Blindfold me and twirl me around twice, and I wouldn't

find my way home. Keep up the great work in congratulations on your success. Um. Yeah, that the whole subject of one's ability to orient orientate yourself in a complex or even familiar environment is a is a very interesting area of study. Yeah, and you can also increase your map sense too. You can actually, um, you know, try to exercise that part of your brain and train it

to increase your abilities. I find with myself because I'm kind of bad at maps, and some of that comes from the reliance on on on these various map tools that we have, such as GPS, such as printing out a map and just knowing you know how many turns to take. And and also I'm I'm terrible at remembering the names of streets, which doesn't help that. Like every street in Atlanta is called Peachtree, uh, which isn't just

a joke. It's like every street Almo, it seems it's name Summer avenues and streets are It's like there are only so many street names that people were allowed to use in every city, and you have to use those. Whereas I think we should have crazier street names. We should name them after you know, I don't know, like Sandworm Avenue, I'd go for that. Who would ever forget sand Worm Avenue? Wouldn't. Well, I've always wanted to do that, honestly. And I thought about it more in terms of subdivisions,

because subdivisions always have these great like falling oaks. Yeah, And I was like, what about just calling that subdivision or that street fallen woman? Yes? Broken Dreams. Yeah, or how about Cloaca Avenue. I like that that would be a good one. That's one that I think I would have that I'd have to steal it and put in my home. Yeah. If it doesn't it, maybe it exists that I hope that it will exist. Please please exist. Um So anyway, Kamala, thanks for riding in and giving

us a little food for thought in that area. It is a very interesting area of study there. There was one really cool episode of I believe it was a radio Lab where they were talking about individuals who have a particular anomaly that makes them extra prone to becoming disoriented in setting. So look that one up. But I believe I shared it on the Facebook. Recently. We also heard from a listener about the name of Valerie. Valerie rights in from Austin, Texas and says, Hi, Robert and Julie.

I was listening to the episode about bats, and it made me think about when I was a kid. I grew up in Santa Fe, New Mexico. For the first part of the year, we have a few Mexican freetailed bats. They come through town on their migration south. One of those bats decided that our porch was an awesome place to use as a temporary home. We went and talked to the local Animal Information center and asked what we

should do. It was a time of year that the bat was either mading, birthing, or something else that needed to not be disturbed. Since the bat needed to not be disturbed while I was living here, we had to stop using our front door. We had to go out our back door, through our backyard and through the gate in the back. That worked moderately well for the for some of the time. For most of that entire summer, we also had to have anyone who visited our house

stop using our door. Now that I look back on it, it seemed like a lot of the time, a lot of time to just stop using our front door. But at the time my parents made it seemed like a really cool thing we were doing for a summer, So that was that was That's really interesting. I remember at one point the house my family lived and had a gazebo, and there's a bat that took refuge up in there,

and so it's kind of neat we had a local bat. Uh. And as I've discussed before, I've tried to get bats to move into the bat house in my home or my previous home, and they wouldn't do it, so it makes me sad. Well, but now Valerie is in Austin that central right the Conquer Street bridge. Oh yes, that's right where they all cluster. Every all right, Well, if the rest of you have anything you would like to share about bats, or about directions, or certainly about fingerprints,

we would love to hear from you. Do you have some sort of unique fingerprint? Do you have no fingerprints? Let us know. We would love to have some perspective on that, for sure. I'm certainly about the the history of fingerprints or simply taking a corpse's hand flesh and slipping it on like a glove and typing. We would love to know about that as well. You can find

us on Facebook, you can find us on tumbler. We are stuff to blow your mind on both of those pages, and we go by the handle blow the Mind on the old Twitter, and you can always drop us a line at blow the Mind at discovery dot com for more on this and thousands of other topics. Is it how Stuff Works dot com