- Fingers wrinkle in water due to contraction of blood vessels, not because skin soaks it up.
- Knowledge about finger wrinkling might have real-world forensic applications.
- Conditions like Raynaud’s disease, dehydration and under-active thyroid can wrinkle fingers.
Here’s news that has little everyday-world application unless you’re into forensics. But it’s oddly fascinating for those who love trivia.
Every time you’ve been in the water too long, your fingers wrinkle in the same identical pattern.
It was a kid’s question that led to the study by researchers at the State University of New York at Binghamton. A couple of years ago, a Binghamton associate professor, Guy German, published a study on why human skin wrinkles when you stay in water too long (it’s mostly fingers and toes). It was once believed that the water swelled skin, but little research had been done to prove it, according to a news release on Science Daily.
Turns out, the skin didn’t swell. It was that the blood vessels beneath the skin contracted after prolonged immersion, leaving the skin looking wrinkly, as the researchers at the Biological Soft Matter Mechanics Laboratory confirmed.
German wrote about that cause in The Conversation’s “Curious Kids” feature and a student stumped him by asking if the wrinkles always looked the same.
His response? “I haven’t the foggiest clue.”
The findings on that by German and Rachel Laytin were published in the Journal of the Mechanical Behavior of Biomedical Materials.
“Blood vessels don’t change their position much. They move around a bit, but in relation to other blood vessels, they’re pretty static,” German reported. “That means the wrinkles should form in the same manner and we proved that they do.”
Wrinkled fingers that haven’t been in water may be related to health conditions and should not be ignored, according to the-scientist.com.
That pruney look
Researchers at Binghamton put their subjects’ fingers in water for 30 minutes, taking photos and doing it again after at least a day. When they looked at the images, they found the same patterns of raised loops and ridges.
They also verified something they’d heard: That people who have median nerve damage in their fingers don’t form wrinkles at all. Turns out that it’s true. They tested it on a student who had median nerve damage and, indeed, he didn’t develop wrinkles.
While the experiment was done for fun to answer the child’s question, German said it could have real-world applications in forensics, including at crime scenes or identifying bodies that have been in water for a long time. The release noted that German’s father is a retired UK police officer who “faced some of these challenges during his law enforcement career.”
German said that he’s anxious to learn more about skin immersion with his students, because so little of the science is known. He said the wonderful questions that kids ask “do create cool new science.”
As for the look of fingers wrinkled by water, “The Sci Kids" show on YouTube likens the wrinkly fingers to what happens when you stretch fabric a lot and then let it relax: It gets all puckery.
Sign of a health issue?
WebMD.com reported that scientists think the process evolved so people would have a decent grip when their hands are wet.
The article also notes that several things can cause pruney fingers without a connection to immersion.
Raynaud’s disease shrinks blood vessels when some people get cold, moving blood away from fingertips and changing the color to red, white or blue and creating wrinkles. There’s sometimes a link between Raynaud’s and lupus, too, or Raynaud’s and scleroderma.
Dehydration can also deplete water and turn skin wrinkly.
An underactive thyroid can cause wrinkles, too, along with rashes, and cool, pale, dry skin.
Lymphedema can tighten skin, causing a wrinkly look.
Wrinkly skin syndrome creates excessive wrinkles on hands, fingers and other places. It’s genetic.
Most of the conditions have treatments that can reduce pruney fingers. And, of course, if it’s a matter of immersion, they will return to normal shortly.
WebMD suggests seeing a doctor if you have signs of dehydration that don’t resolve by cooling down and hydrating. Those signs can include vomiting, diarrhea, not urinating, weak or fast pulse, seizures, exhaustion, confusion and dizziness.
You should also see a doctor for skin problems accompanied by feeling tired a lot, having cold hands and feet, sore joints or unusual weight gain.