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Scientists Wonder What Fingerprints Are For

Hugh Pickens writes "The BBC reports that scientists say they have disproved the theory that fingerprints improve grip by increasing friction between people's fingers and the surface they are holding. Dr Roland Ennos designed a machine which enabled him to measure the amount of friction generated by a fingerprint when it was in contact with an acrylic glass at varying levels of pressure. The results showed that friction levels increased by a much smaller amount than had been anticipated, debunking the hypothesis that fingerprints provide an improved grip. Ennos believes that fingerprints may have evolved to grip onto rough surfaces, like tree bark; the ridges may allow our skin to stretch and deform more easily, protecting it from damage; or they may allow water trapped between our finger pads and the surface to drain away and improve surface contact in wet conditions. Other researchers have suggested that the ridges could increase our fingerpads' touch sensitivity."

40 of 347 comments (clear)

  1. Primates by MichaelSmith · · Score: 4, Interesting

    I noticed this at the zoo watching a bunch of monkeys swing from branch the branch in a cage. The tree branches they had been given had been worn smooth through long use and every time a monkey grabbed on to a smooth branch I felt a jab in my fingers in sympathy. There is something bad about grabbing a smooth object and relying on it to save your life.

    So maybe finger prints improve grip with smooth timber surfaces. Testing against glass doesn't sound very realistic. We didn't evolve to grip glass. Or maybe (as the summary suggests) it is something to do with detecting the texture of a surface to find a place to grip.

    Of course they don't ask why people have unique finger prints. Maybe it evolved to make murderers easier to catch.

    1. Re:Primates by Anonymous Coward · · Score: 3, Insightful

      There are probably multiple reasons for the fingerprints.

      The skin has to be both flexible and durable at the same time, and gripping on moist surfaces should also be safe.

      A flexible skin is also allowing for better dexterity and a finer resolution when sensing surfaces.

    2. Re:Primates by Threni · · Score: 3, Interesting

      The fingerprints we have now may be little use for increasing friction, but perhaps at some point in the past before they'd evolved away they'd have been been more pronounced, and would have trapped sticky dirt within more efficiently than todays generally cleaner hands.

    3. Re:Primates by jonbryce · · Score: 3, Interesting

      Or maybe it didn't evolve that way for any particular reason.

      These sort of studies assume we have now evolved to perfection. But that suggests there will be no further evolution, which I don't think is the case.

    4. Re:Primates by Anonymous Coward · · Score: 3, Interesting

      "Of course they don't ask why people have unique finger prints."

      What are the other unique features? Vein patterns and eye color patterns are as unique as finger prints. The odds are the uniqueness is a function of growth unrelated to purpose.

    5. Re:Primates by houghi · · Score: 5, Funny

      We didn't evolve to grip glass.

      Yes we did. The better you can hold your glass, the more alcohol you are able to drink. The more alcohol you drink, the more likely you are to end up with some ugly girl who also was able to drink herself unconscious.

      Now imagine that you would drop your glass before you are at that point. You would never be drunk enough to go with THAT girl and she won't go home with YOU.

      Without fingerprints, we would be extinct by now.

      --
      Don't fight for your country, if your country does not fight for you.
    6. Re:Primates by jonbryce · · Score: 3, Informative

      Not really. Survival of the fittest means survival of those most able to have lots of children, and that's as valid now as it has ever been.

    7. Re:Primates by stonewallred · · Score: 5, Insightful

      most evolutionary features get kept that do not kill the person/animal having it, and which does not put it at a disadvantage in reproducing. There are many more evolved features that do nothing that have been kept than you think.

    8. Re:Primates by Reziac · · Score: 5, Insightful

      Exactly -- why does it have to be for any particular use? More likely it's just an artifact of how skin develops. People forget that many traits didn't evolve for a specific purpose, but rather, were random mutations that were not selected against, becauee they did the species no harm.

      The whole question also shows a profound ignorance of the rest of the animal kingdom:

      Dogs have noseprints that are as unique as fingerprints (and in fact are legal ID for dogs in Canada). Why is this? Probably no reason at all, other than quirks of individual cell layout in the skin layer.

      Chickens have similar uniqueness in the surface of their combs. Why? Likewise, probably no reason, other than it's just a trivial quirk of how the skin cells piled up in a given individual.

      --
      ~REZ~ #43301. Who'd fake being me anyway?
    9. Re:Primates by linguizic · · Score: 3, Informative

      It depends on what scale you're looking at. Neutral Theory says that MOST mutations are neither beneficial nor harmful.

      --
      Does this sig remind you of Agatha Christie?
    10. Re:Primates by beowulfcluster · · Score: 3, Funny

      Fingerprints would probably evolve away within a few generations if people didn't need the increased friction on the iPod click wheel.

    11. Re:Primates by Reziac · · Score: 3, Insightful

      Dogs often use their noses like a jack-hammer... the nosepad is not particularly sensitive to touch. If your dog is too wiggly to get a noseprint (which one does with a paper-pad and roll-on ink, much as one would footprint a baby), chances are the dog needs more training, and you need lessons on how to be the pack leader, too.

      (Disclosure: I am a professional dog trainer. :)

      --
      ~REZ~ #43301. Who'd fake being me anyway?
    12. Re:Primates by daymitch · · Score: 3, Interesting

      This doesn't follow (that there should be folks without fingerprints if they have no purpose). It depends on the genetic basis of fingerprints and the genetic history of our species.

      One thing we have learned about human genetics is that the human population went through several 'bottlenecks' where the population was reduced to low numbers. Is this what you are referring to?

      It's a process called genetic drift. My old botany prof described it with a fun story. Imagine some disaster that reduces the entire human species to a small group on a raft. Everyone is dark-skinned except for Gunter, a blonde-haired, blue-eyed nordic type. Gunter trips and falls off the raft and gets carried away by the current (he drifts away, get it).

      It's an accident that has nothing to do with his reproductive potential. Anyone else could just as easily have had the same accident. If they had, the genes for blonde-hair and blue eyes would still be in the human population and human evolutionary history would be different in that respect. Small population sizes increase the importance of drift.

      Of course, other factors come in to play when you imagine the difficulties a fair skinned guy would have on a raft relative to other human types. That's another story.

  2. Intelligent design by Anonymous Coward · · Score: 5, Funny

    It's obvious fingerprints were designed by our creator to help the Police catch murderers.

    1. Re:Intelligent design by mark-t · · Score: 3, Funny

      Close... they were designed by our creators so that _they_ could tell us apart... because otherwise we all look too much alike to them. Like a field of daisies.

  3. CSI may have an alternate hypothesis to their use. by gblackwo · · Score: 5, Funny

    I also love how they never counterweight their centrifuges.

  4. Maybe they're for nothing? by Karganeth · · Score: 3, Insightful

    If it takes an equal amount of resources for the body to grow a finger without fingerprints then it makes sense that they not meant for anything. Not everything has to have a purpose.

    1. Re:Maybe they're for nothing? by digitig · · Score: 5, Interesting

      Careful with "purpose" -- Evolution is non-teleological, and "purpose" has no place in evolutionary explanations. I think you mean that everything has to ba adaptive, but even then I wonder how you know -- surely evolution would allow characteristics that are not adaptive as long as they have no cost. In fact, evolution depends to some extent on things that are not necessary, as Stephen J Gould pointed out -- a part of an organism can only adapt to a new function if it's not needed for something else.

      --
      Quidnam Latine loqui modo coepi?
    2. Re:Maybe they're for nothing? by maxume · · Score: 5, Insightful

      Or a population of primates that happened to have fingerprints became dominant for some other reason.

      It is often the case that an environmental shift makes an existing trait advantageous (that trait may have been meaningless in the previous environment), rather than an advantageous trait arising in a static environment.

      --
      Nerd rage is the funniest rage.
    3. Re:Maybe they're for nothing? by funkatron · · Score: 4, Insightful

      If we have fingerprints, it's genetically possible to be born without, so it's very likely that that mutation existed in the history of evolution, and that one of those specimen procreated, creating that fingerprint-less type of monkey/man.

      I would actually question to what extent this is a possibility. Human skin has all sorts of textures and patterns, most of which we don't treat with any significance. It may be that smooth skin is actually difficult to produce by biological processes. This is a possibility that should at least be considered.

      --
      "Welcome to our world. We are the wasted youth. And we are the future too." Yes, I know these are stupid lyrics.
  5. Re:what do you think? by malchus842 · · Score: 5, Insightful

    Throughout history, there have been lots of questions that science has not been able to answer. But science is not static. Over time, it has been able to answer more and more questions and close more and more of the 'gaps.'

    For any theist, the 'God of the Gaps' defense is pretty weak. Just because we don't understand something doesn't require a God (or gods) to explain it.

    This is not a rejection of theism, but simply a comment on science - just because we don't have an answer now doesn't mean we won't have an answer in the future. And not having an answer does not imply that there is a (or many) God(s).

  6. Re:what do you think? by Mascot · · Score: 5, Funny

    Just one more thing science can't answer. Of course the answer is obvious but no scientist would ever consider that.

    Agreed. I'm not a scientist and to me the answer is as obvious as it is to you.

    It is clearly a case of aliens genetically modifying the species to easily identify individuals; we do the same in tagging wildlife.

  7. Re:CSI may have an alternate hypothesis to their u by Joebert · · Score: 4, Informative

    They use auto-balancing centrifuges.

    --
    Wanna fight ? Bend over, stick your head up your ass, and fight for air.
  8. Ridged for extra pleasure? by itsdapead · · Score: 5, Funny

    Sorry.

    I'll get my coat.

    --
    In a survey of 100 programmers, 111111 thought that duck-typing was a good idea.
    1. Re:Ridged for extra pleasure? by Anonymous Coward · · Score: 3, Funny

      Make sure you have more than just the coat, okay?

  9. tactile sensation by Anonymous Coward · · Score: 5, Informative

    There is a fair amount of evidence that they increase tactile sensitivity. We have nerves that are sensitive to specific vibrational frequencies. As fingerprints run over edges, then generate vibrations at frequencies we have maximal sensitivity for.

    http://www.sciencemag.org/cgi/content/abstract/323/5920/1503

  10. ummm where did captain obvious go? by meow27 · · Score: 5, Interesting

    "Other researchers have suggested that the ridges could increase our fingerpads' touch sensitivity."

    from TFA (sorry i can figure out how to use the quote function :/)

    how is this not obvious? where he have some sort of ridge like pattern (hands, feet) we have more sensitive nerves there. The ridges increase surface area of our skin which means we can feel more using up less volume

    the star nosed mole is the perfect example of increased surface area for more touch sensitivity.

  11. Re:what do you think? by aplusjimages · · Score: 4, Funny

    Hi 120795, I'm 939458. It's very nice to meet you.

    --
    Can I bum a sig?
  12. National Public Radio's Science Friday by Anonymous Coward · · Score: 5, Informative

    The USA's National Public Radio show, "Science Friday" discussed this:

            http://www.npr.org/templates/story/story.php?storyId=105310429&ft=1&f=5

    The show talks about this result, and reveals that New world monkeys have similarly ridged
    skin on the gripping side of their tails. Touch sensitivity, and resistance to blistering are
    posited as potential answers.

  13. Many things by bytesex · · Score: 4, Insightful

    More grip, larger surface, which means more flexibility, more nerve-endings - more sensitivity, better warmth-exchange, 'folded-up-ness', which means more protection from wounds, easier to clean (like footprints, the mud just falls out), 'little bits that stick out' - meaning more sensitivity again.

    --
    Religion is what happens when nature strikes and groupthink goes wrong.
  14. Bad science or bad journalism? by YourExperiment · · Score: 5, Insightful

    With articles such as this, it's hard to tell whether we're being subjected to bad science or bad journalism. Both the summary and TFA quite categorically state that the "myth" of fingerprints being used to improve grip has been disproven. They then go on to describe how this experiment tested whether fingerprints helped when grasping an extremely smooth surface, and found out that they didn't (well okay, actually they did, but not by very much).

    Finally, some alternate hypotheses as to why fingerprints evolved are posited, the first of which is: they may improve grip on rough surfaces. Not acrylic glass or anything, but those other kind of surfaces - you know, the type that actually occur in nature.

    I'm pretty sure I don't know much more now than I did before I read the article.

  15. The real question is: by Hurricane78 · · Score: 3, Informative

    Why do they have to be for something?
    Evolution does not forbid random things, that are neither bad nor good for something.

    Sometimes, humans try too much, to fit things into the artificial set of meta-rules that they did create, to describe the complex results of more basic and emergent rules. But those meta-rules have their own artifacts, that are not present in the basic rules and therefore are not present in the world. Like there having to be a "reason" for everything. A human concept that should describe causality, but adds something more to it, which does not exist in reality.

    Other than that, it is obvious, that they enhance the grip, even in situations with liquids.

    --
    Any sufficiently advanced intelligence is indistinguishable from stupidity.
  16. Picking your nose by goombah99 · · Score: 4, Funny

    Picking your nose seems like a good enough reason.

    --
    Some drink at the fountain of knowledge. Others just gargle.
  17. Re:what do you think? by jonbryce · · Score: 3, Insightful

    "I believe there is no God" is as much a statement of faith as "There is no God but Allah, Muhammad is his messenger". There is no scientific evidence to prove or disprove either statement.

  18. Re:What fingerprints are for by Bob9113 · · Score: 4, Funny

    Other than that they serve no other purpose, like wasps.

    Hey, if it weren't for WASPs, who would shop at The Gap or Banana Republic? Who would buy purse-sized dogs? And who would keep psychotherapists and badminton set manufacturers in business?

  19. Re:what do you think? by vadim_t · · Score: 4, Informative

    Most atheists explain it as "I won't believe until I see proof of it", though, which is very much scientific.

  20. Re:what do you think? by Fribulator · · Score: 4, Insightful

    Although that seems like a good idea at first, if the treatment was powerful enough to remove his fingerprints, it could have caused some nerve damage as well, which could cause his diminished sensitivity. However, if he (and other such people) were to submit to tests and scans and general research, they would surely prove helpful in deciphering the mystery of the fingerprint.

  21. Re:Different finger prints by osu-neko · · Score: 3, Informative

    Even without errors in copying the genetic code, people get unique finger prints. The overall pattern and general style will end up the same, but they're still unique, even between twins with identical DNA. Reminds me of the markings on the cloned cat. The clone was a calico, just like the original, but that seemly random pattern in a calico's fur? Turns out, it actually is somewhat random. Identical DNA doesn't produce identical fingerprints either...

    --
    "Convictions are more dangerous enemies of truth than lies."
  22. It's wet grip by R2.0 · · Score: 5, Interesting

    I've had the experience of having no fingerprints for a time. I worked at UPS unloading trucks; one of the customers shipped many thousands of small boxes just before the end of the year; the boxes were the precise size that the only way to grip them was with the pads of fingers and thumb (I'm looking at you, Daytimers!). A large portion of those boxes passed through my hands. Shortly after I started work there, I noticed that I was having trouble gripping items that were wet - a water glass with condensation on it would routinely slip through my fingers. When I examined my hands I saw that the ridges of my fingerprints were basically worn away. I wore gloves for a bit while working and the problem cleared itself up.

    Another illustration would be to look at the skiving on the bottom of a pair of deck shoes. On a dry surface, they offer no advantage whatsoever, but on a wet surface the difference in grip is remarkable. Or for that matter tire treads - a set of slicks is the absolute best way to maximize grip - unless it's wet, at which point they become the WORST configuration.

    --
    "As God is my witness, I thought turkeys could fly." A. Carlson
  23. Re:Ribbed for extra ...? by Jah-Wren+Ryel · · Score: 4, Funny

    Perhaps they helped attract mates?

    Naturally ribbed, err... fingers, for her pleasure?

    --
    When information is power, privacy is freedom.