Why Fingers Wrinkle in Water may Finally Have an Explanation

After discovering the blood vessels responsible for finger wrinkles in water, young readers of The Conversation’s Curious Kids series had more questions for scientists:

“Do the wrinkles always form the same way?” one reader asked.

Curiosity Sparks a Scientific Investigation

“I thought, ‘I haven’t the foggiest clue!‘” recalls Guy German, a biomedical engineer from Binghamton University in New York and author of the educational article. “That’s when I decided to investigate further.“

German and his colleague Rachel Laytin enlisted three volunteers to soak their fingers for 30 minutes. The images showed that the looped peaks and valleys on the participants’ wet fingertips largely repeated when soaked again 24 hours later.

As water enters through open sweat ducts into the skin, it lowers the salt concentration in the outer layer. Nerve fibers detect this change and signal the brain, which then triggers the automatic contraction of blood vessels.

As these small skin vessels constrict, they pull the surface of our skin, causing once-smooth fingers and toes to become wrinkled and pruney.

“Blood vessels don’t shift much—they move slightly, but in relation to other vessels, they remain fairly stable,” German explains. “This means the wrinkles should form consistently, and we confirmed that they do.“

Nature’s Grip Enhancement

This wrinkling isn’t merely a random occurrence. The changes in skin texture offer a practical benefit in wet conditions: the temporary grooves and ridges enhance grip, making it easier to walk on or hold slippery objects.

Although these wrinkles provide enhanced grip, it’s curious that we don’t keep them permanently. While researchers aren’t certain why, they believe the temporary texture may reduce finger sensitivity or increase the risk of injury.

It was once believed that swelling caused soaked skin to wrinkle, but a 2016 study showed that skin would need to swell by at least 20 percent for that to occur. Additionally, earlier research found that people with nerve damage don’t experience finger wrinkling, prompting further exploration of the underlying mechanisms.

“We’ve heard that wrinkles don’t form in people with median nerve damage in their fingers,” says German. “One of my students mentioned he had median nerve damage, so we tested him – no wrinkles!“

Beyond satisfying curiosity, these insights could prove valuable in forensics. For instance, understanding how finger skin distorts could help identify bodies after prolonged water exposure, such as following natural disasters.

Thus, wrinkle patterns can now be added to the unique set of skin features we all share, alongside fingerprints and hidden skin lines.

Read the original article on: Sciencealert

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