Science

Ever Wonder How and Why You Get ‘Pruney’ Fingers?

Ever wondered why your fingers and toes wrinkle after a long soak? We did. And we found it actually serves a purpose, according to some scientists.

According to Nature, Mark Changizi, an evolutionary neurobiologist at 2AI Labs in Idaho, thinks they could be “rain treads” that make it easier for us to grip things in wet environments. Nature has more on the study published in the Brain, Behavior and Evolution back in June:

Scientists have known since the mid-1930s that water wrinkles do not form if the nerves in a finger are severed, implying that they are controlled by the nervous system.

“I stumbled upon these nearly century-old papers and they immediately suggested to me that pruney fingers are functional,” says Changizi. “I discussed the mystery with my student Romann Weber, who said, ‘Could they be rain treads?‘ ’Brilliant!’ was my reply.”

. . .

The sides of the finger are like cliffs where water can easily fall away, but the flat part is more like a plateau where water can pool. Wrinkles form on the plateau because “that’s where all the work has to be done to channel the water away”, Changizi explains.

Scientists Think Finger, Toe Wrinkles Function Help Grip in Slippery Conditions

Mark Changizi analyzed the patterns of finger wrinkles from photographs and likened them to tire treads. (Photo: Mark Changizi)

Some scientists aren’t quite on board, saying that the water wrinkles are just the mechanics of the skin reacting with the exposure to moisture.

Either way — if wrinkles serve a purpose or occur for no reason at all — what is happening to cause them in the first place? How often have you or your kids asked that question? Well, here’s a shortened answer from Dermatologist Laurence Meyer of the University of Utah via Scientific American:

The epidermis, or outer layer of the skin, is made up of cells called keratinocytes, which form a very strong intracellular skeleton made up of a protein called keratin. These cells divide rapidly at the bottom of epidermis, pushing the higher cells upward. After migrating about halfway from the bottom of this layer to the top, the cells undergo a programmed death. The nucleus involutes, leaving alternating layers of the cell membrane, made of lipids, and the inside, made largely of water-loving keratin. The outer layer of the epidermis, called the stratum corneum, is thus composed of these alternating bands.

When hands are soaked in water, the keratin absorbs it and swells. The inside of the fingers, however, does not swell. As a result, there is relatively too much stratum corneum and it wrinkles, just like a gathered skirt. This bunching up occurs on fingers and toes because the epidermis is much thicker on the hands and feet than elsewhere on the body. (The hair and nails, which contain different types of keratin, also absorb some water. This is why the nails get softer after bathing or doing the dishes.)

While that’s a little complex, he’s basically saying that layers of dead skin cells on our outermost layer of skin absorb water. Because skin cells underneath this layer are not dead, they do not absorb water and the water-logged dead cells on top wrinkle. Discovery Magazine describes this like so:

. . .since the epidermis is “tied” down to your dermis, [the live cells,] in certain spots, it expands more where it is not “tied” down and this causes your skin to wrinkle.

Watch this video if you want to see it explained:

To recap: Meyer‘s explanation for the wrinkles on hands and feet are that it’s where keratin, the substance absorbing the water, is the most thick; Changizi takes it one step further in noting that the wrinkles are most prominent on the ends of digits — the first parts to touch a water.

To further test his hypothesis, Changizi is looking into if people with wrinkled fingers are better at gripping in wet conditions. “We began pilot experiments,” says Changizi. “The results thus far suggest that, yes, being pruney helps.”

Comments (68)

1 2
  • chipmunk
    Posted on September 16, 2011 at 12:35am

    Ever wondered why your fingers and toes wrinkle after a long soak?

    No.

    Report Post »  
    • rangerp
      Posted on September 16, 2011 at 6:52am

      Wow, interesting science. Now can you tell us why Nancy Pelosi is so dad gum ugly?

      Report Post » rangerp  
    • HellAndBack
      Posted on September 16, 2011 at 8:45am

      Thats the investation and personification of EVIL!

      Report Post » HellAndBack  
    • Sheepdog911
      Posted on September 16, 2011 at 11:01am

      OK, now explain why some people have in-ies and some have out-ies? Or why belly buttons collect lint?

      Report Post » Sheepdog911  
  • CaliforniaArtist
    Posted on September 15, 2011 at 9:16pm

    Only one of these explanations seems to be correct since both logically cannot.

    “Scientists have known since the mid-1930s that water wrinkles do not form if the nerves in a finger are severed, implying that they are controlled by the nervous system.”

    or

    “When hands are soaked in water, the keratin absorbs it and swells. The inside of the fingers, however, does not swell. As a result, there is relatively too much stratum corneum and it wrinkles”

    If the second explanation is correct, the fingers would wrinkle regardless if the nerves are severed or not.

    If the first explanation is correct and nerves are responsible, then keratin water absorption would still occur whether or not the nerves were severed.

    This profound question could be settled if some reader with loss of nerve sensation and/or nerver motor control in one or more fingers, soaked their finger(s) in water to find out.

    Report Post »  
    • teamarcheson
      Posted on September 15, 2011 at 10:06pm

      God thinks of everything.

      Report Post »  
    • kcowboy28
      Posted on September 15, 2011 at 11:24pm

      When I first read the article I thought Wow that’s pretty neat. However I very quickly remembered that dead bodies found in water have wrinkled hands and feet as well. Unless I am mistaken, your nervous system shuts down when you die. So I do not believe your nervous system controls it. It’s simply exposure to water.

      Report Post »  
    • zoose
      Posted on September 16, 2011 at 12:26am

      After a soggy 7 1/2 years in the NAVY, this is pure bunk.

      Report Post » zoose  
    • RavenGlenn
      Posted on September 16, 2011 at 12:43am

      I actually posted(or so I thought…it seems the site decided not to post my message) the same thing earlier.

      Both of these cannot be true as they contradict one another. If those with severed nerves do not prune, then the business about dead skin cells soaking up water cannot be the case.

      Report Post »  
    • cozmo
      Posted on September 16, 2011 at 12:48am

      If it only happens on your hands where the skin is thicker then there would be evidence of it elsewhere on your body just not a prominent. I have never noticed my knees wrinkling in water or my elbows and although I haven’t measured the thickness of skin there it feels thick.

      Report Post »  
    • On The Silent Wings Of Freedom
      Posted on September 16, 2011 at 4:36am

      When I was a senior in High School I had an accident in wood shop while operating the table saw. I severed both tendons in my middle finger, and one in my index finger, along with all the associated nerves. I lost feeling in my middle finger, and along one side of my index finger. IT IS TRUE, that the finger with complete nerve damage DOES NOT WRINKLE when soaked, while my index finger wrinkles on one side only. Further more, my hand surgeon was well aware of this phenomenon back in 1974 when the incident occured. In fact, it was one of his methods for determining the extent of nerve damage. So this is not even new information. Wonder how these folks missed it?

      Report Post » On The Silent Wings Of Freedom  
    • On The Silent Wings Of Freedom
      Posted on September 16, 2011 at 4:47am

      (Continuing from above)
      Not that they missed the fact about severed nerves, but they ignored the “connection” (or lack thereof) of the nerves affect on wrinkling.

      Report Post » On The Silent Wings Of Freedom  
  • pennsylvaniaman
    Posted on September 15, 2011 at 8:43pm

    Or maybe God created evolution to create us……

    Report Post » pennsylvaniaman  
  • jinkxed
    Posted on September 15, 2011 at 10:31am

    Ya’ know, I remember Glenn saying on the radio about The Blaze, “give them stories that they can’t get anywhere else”. Really? So we end up with a story about “pruney” fingers? I guess it’s true no other news outlet is reporting on “pruney” fingers. But, really? I think The Blaze needs to make a new category that isn’t part of the “front page news” of the site called “Completely Useless Information” and stick stuff like this in that section. I mean it’s not exactly a headline breaker. I guess at least now I can sleep peacefully at night knowing why my fingers get “pruney”.

    Report Post »  
    • CONSERVATIVE SUMMER
      Posted on September 15, 2011 at 12:07pm

      Slow news day….

      Report Post » CONSERVATIVE SUMMER  
    • Heather Mae 74
      Posted on September 15, 2011 at 6:29pm

      I have to admit that this is something that I have wondered about, I guess I’m a useless information junkie

      Report Post » Heather Mae 74  
    • RabidPatriot
      Posted on September 15, 2011 at 6:39pm

      This website needs a better Chief Editor. It is extraordinarily inconsistent. It will have legitimate breaking news that everyone should know about, followed by a story that is incomplete and designed by its writer to just stir the pot of government discontent (usually with headlines that are only partly accurate). Then there are trivial stories about pruney fingers. If that is the type of news site they are after then… success. They need someone to review articles and reject the BS for rewrites. Leave the half-truths to the HuffPost and MediaMatters.

      Report Post » RabidPatriot  
    • mauijonny
      Posted on September 15, 2011 at 7:34pm

      Geeze. Lighten up. And, yes, Blaze, I HAVE wondered why.

      Report Post » mauijonny  
    • TXBadOneToo
      Posted on September 16, 2011 at 1:05am

      If you don‘t likethe topic of an article posted on the Blaze wouldn’t it make more sense to just pass it by rather than spend your time to type a comment and whine? I’m guessing you just like/need to whine. I’m personally GLAD that Glenn has created The Blaze and provides me with a good way to scan topics I choose to read or not read..

      Report Post »  
  • Keven_M_Thomas
    Posted on September 15, 2011 at 10:19am

    maby “evolution” knew we have many many men in prison and that would help them to hold the soap.

    Report Post » Keven_M_Thomas  
  • BobtheMoron
    Posted on September 15, 2011 at 9:59am

    Attack AttackWatch. Post recipes or anything that makes you smile. Obama limericks might be good.

    Report Post » BobtheMoron  
  • SpankDaMonkey
    Posted on September 15, 2011 at 9:28am

    .
    You went to the University got a phd. and this you think is new…….

    Dude a guy used pruney fingers and a dog paw to design the bottom of top siders…….

    Report Post » SpankDaMonkey  
  • 50stars13stripes
    Posted on September 15, 2011 at 9:27am

    Amazing, God designed or evolution? I lean towards the higher power, to God be the glory!

    Report Post » 50stars13stripes  
    • bookofdaniel
      Posted on September 16, 2011 at 2:07am

      Read my book; “Evolution, The Bio-Logic of God” by Daniel L. Bell

      Report Post »  
  • TomFerrari
    Posted on September 15, 2011 at 9:20am

    Why do men’s pants get tighter when…

    nah, never mind…
    .
    .

    Report Post » TomFerrari  
  • loadingmyclips
    Posted on September 15, 2011 at 8:53am

    No

    Report Post » loadingmyclips  
  • Gonzo
    Posted on September 15, 2011 at 8:43am

    I‘m more curious about why Barry’s lips are always purple. Grape popsicle addiction or what?

    Report Post » Gonzo  
    • John 3:16
      Posted on September 15, 2011 at 11:28am

      Obama’s lips are purple because of the lack of blood to his head, it’s an extreme evolutionary socialist trait. The up side is you can see when his lips move thus it’s easier to tell when he is lying.

      Report Post » John 3:16  
    • HD Veteran
      Posted on September 15, 2011 at 11:57pm

      John 3:16 Funny as hell man.

      Report Post » HD Veteran  
  • batteredtaxpayer
    Posted on September 15, 2011 at 8:39am

    Thus the 1 minute shower!

    Report Post »  
  • planejet
    Posted on September 15, 2011 at 8:36am

    How much did the study cost and who paid for it? Was it money well spent?

    Report Post »  
  • Secessionista
    Posted on September 15, 2011 at 8:25am

    But they still can’t tell us why prunes get pruney.

    Report Post » Secessionista  
  • Secessionista
    Posted on September 15, 2011 at 8:24am

    Yambag? Now that’s funny, I don’t care who you are!

    Report Post » Secessionista  
  • oldsoldier10
    Posted on September 15, 2011 at 8:07am

    George Bush causes wrinkled fingers and $500 million in loan defaults, and earth quakes in NY.

    Report Post » oldsoldier10  
  • Inlandmar2
    Posted on September 15, 2011 at 8:05am

    My life is now complete. The final and greatest question of life has been answered. At last the mystery of “pruney” fingers has been revealed. I can now die a happy man.

    Report Post » Inlandmar2  
  • Bobby P
    Posted on September 15, 2011 at 7:52am

    This doesn’t explain why my yambag is wrinkled.

    Report Post » Bobby P  
    • oldsoldier10
      Posted on September 15, 2011 at 8:05am

      easy answer, you are old and it is unused.

      Report Post » oldsoldier10  
    • Codger
      Posted on September 15, 2011 at 8:06am

      LmAo!

      Report Post » Codger  
    • alina.bolero
      Posted on September 15, 2011 at 8:15am

      ROFLMFAO … OMG that was funny!

      Report Post » alina.bolero  
    • ubtaught
      Posted on September 15, 2011 at 8:38am

      Yambag? How does one actually read a magazine like Scientific American while calling the scrotum a ‘yambag’?
      People; there are scientifically and medically correct names for things. Use them. I can‘t imagine a locker room so bereft of rational thought and so reeking of testosterone where the term ’yambag’ is even considered.
      I thought the term ‘junk’, when used to refer to the external, male genitalia, was the epitome of irrational behavior but I have been proven wrong yet again. No wonder our children are confused. How can a child, when confronted with the idea that dad‘s ’yambag‘ injected stuff through dad’s junk into mom’s cooch and I was created, grow up to be anything but terminally confused?

      Report Post » ubtaught  
    • trolltrainer
      Posted on September 15, 2011 at 9:10am

      UBTAUGHT,

      ……er

      ah………why do…..er……..

      hmmmm

      never mind, just shut your pie hole….

      Report Post »  
  • ingvard
    Posted on September 15, 2011 at 7:48am

    And some try to say there is no God or creator. Millions of years of evolution my @%%&

    Report Post »  
    • Johnny916
      Posted on September 15, 2011 at 7:54am

      What do you mean? I believe in both creation and evolution. Don’t you?

      Report Post »  
    • DagneyT
      Posted on September 15, 2011 at 8:08am

      That was my response to this article, as well as the earlier one on the changes in men after the birth of their children. God has engineered us with His Own purposes! The more you see the engineering, the more you see His Hands at work. Evolution is difficult to prove because it is faulty, and leaves out the Creator.

      Report Post » DagneyT  
    • trolltrainer
      Posted on September 15, 2011 at 9:12am

      Define evolution Johnny?

      Did we evolve from monkey creatures that evolved from amoebas? Er…no….

      And there is no way to logically reconcile that belief with a biblical belief in God.

      Report Post »  
    • bookofdaniel
      Posted on September 16, 2011 at 2:12am

      Read my book; “Evolution, The Bio-Logic of GOD” by: Daniel L. Bell

      Report Post »  
  • Johnny916
    Posted on September 15, 2011 at 7:47am

    This is awesome! I’m a believer in evolution and enjoy reading this.

    Report Post »  
    • trolltrainer
      Posted on September 15, 2011 at 9:13am

      This is awesome! I’m a believer in God and enjoy reading this.

      Report Post »  
    • code green
      Posted on September 15, 2011 at 11:31am

      This is awesom. I can‘t believe that some are so arrogant that they don’t believe Gods plan doesn’t include evolution, I enjoy stirring the pot.

      Report Post »  
    • trolltrainer
      Posted on September 15, 2011 at 12:11pm

      ar·ro·gant/ˈarəgənt/
      Adjective: Having or revealing an exaggerated sense of one’s own importance or abilities.

      Read Genesis chapter 1 and then explain how monkey to man evolution can fit in. If you are merely stating that organisms adapt then I have no argument with you, but be careful using the term “evolution.” It actually is not evolution as the changes are due to the loss of genetic information, not the acquiring of new information.

      Man is arrogant…I trust the Bible. Stir away.

      Report Post »  
    • bookofdaniel
      Posted on September 16, 2011 at 2:21am

      The only problem with the concept of evolution is that man is giving it the glory. That would be like me telling a person I built my house and he respond by saying; “You did not build your house, your hands did.”
      ” Evolution, The Bio-Logic of GOD! ”
      (the book by: Daniel L. Bell)

      Report Post »  
  • TxMadMac
    Posted on September 15, 2011 at 7:36am

    Thankyou for this article ! My head was about to explode and blood was shooting out of my eyes with the latest daily round of bully bs and criminal activities from the top down ! One thing I have discovered though, pruny fingers don’t help a bit when it comes to picking up a wet bar of soap !

    Report Post »  
  • kickagrandma
    Posted on September 15, 2011 at 7:29am

    Man, if science in junior high and high school had been like this, I would’ve loved it. When we grew up it was dull, dull, dull, dull, as were most of the science teachers. At least to me it was…. *sigh*

    Report Post »  
  • GhostOfJefferson
    Posted on September 15, 2011 at 7:29am

    Next up: How beer goggles have helped propagate the Human race.

    Report Post » GhostOfJefferson  
  • simply one voice
    Posted on September 15, 2011 at 7:24am

    They should investigate nerve damage and loss to the fingers and hands, too. Something’s happening.

    Report Post » simply one voice  
  • USAqh
    Posted on September 15, 2011 at 7:23am

    Gee Whiz … and only yesterday, while I was floating in the pool, I began to ask just that question … The Blaze must be clairvoyant …

    Report Post » USAqh  
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