Spend a few minutes in a bath or pool, and your fingertips transform into wrinkled folds. A recent study shows these wrinkles form the same pattern every time. Interestingly, only fingers and toes wrinkle—other body parts remain smooth.
Scientists once thought wrinkling was a passive response, caused by water entering the skin through osmosis. But as early as 1935, researchers found that people with damaged median nerves—responsible for sympathetic functions like blood vessel constriction—didn’t experience wrinkling. This indicated a neurological cause.
What causes our fingers to wrinkle
It takes about 3.5 minutes in warm water (40°C) or up to 10 minutes in cooler water (20°C) for wrinkles to appear. Studies show full wrinkling occurs after 30 minutes. Interestingly, soaking hands in warm vinegar accelerates the process to just four minutes.
In 2003, neurologists Einar Wilder-Smith and Adeline Chow found that blood flow decreases during wrinkling. Using anesthetic cream to constrict blood vessels produced the same effect.
“It makes sense when you look at your fingers when they go wrinkly,” says Nick Davis, a neuroscientist at Manchester Metropolitan University. “The finger pads go pale and that is because the blood supply is being constricted away from the surface.”
Wilder-Smith proposed that water enters through sweat ducts, disrupting salt balance, which triggers nerve activity and vessel constriction. This loss of volume causes the skin to pull down into wrinkles.
Biomechanical engineer Pablo Saez Viñas adds: “If you don’t have that neurological response, which happens in some individuals, wrinkles are inhibited.”
Why did our fingers evolve to wrinkle in water?
Davis, prompted by his child’s bath-time question, tested 500 volunteers gripping plastic objects. Wrinkled fingers improved grip even while wet.
“The results were amazingly clear,” he says. “The wrinkling increased the amount of friction between the fingers and the object.”
His findings matched a 2013 study by Newcastle University, which showed wrinkled fingers helped volunteers transfer wet objects 12% faster than when their fingers were wet but unwrinkled.
The wrinkles may act like tyre treads, pushing water away to improve grip—suggesting an evolutionary advantage, possibly for gripping wet branches or handling food like shellfish.
“Since it seems to give better grip under water, I would assume that it has to do with either locomotion in very wet conditions or potentially with manipulating objects under water,” says Tom Smulders, the Newcastle neuroscientist who led the study.
Japanese macaques, known for hot spring bathing, also show wrinkling, though no widespread data exists on other primates.
Why do our fingers wrinkle in the bath?
Fingertip wrinkling is less pronounced in saltwater and takes longer. This may suggest the adaptation is linked to freshwater environments. But not everyone agrees it’s evolutionary—some think it may be coincidental.
What can we learn from the wrinkles?
Interestingly, women’s fingers wrinkle more slowly than men’s. And although wrinkles help with wet grip, they disappear within 10–20 minutes when dry—raising questions about why our skin doesn’t stay wrinkled if there’s no downside.
“Some people have a real aversion to it because picking something up with wrinkly fingers feels weird,” says Davis. “It could be because the balance of skin receptors have changed position... There could be other things we can do less well with wrinkly fingers.”
Medically, wrinkling provides surprising clues. It forms slower in people with conditions like psoriasis and vitiligo. Cystic fibrosis patients show excessive palm wrinkling—even carriers of the gene do. Those with type 2 diabetes or heart failure often show reduced wrinkling. Asymmetrical wrinkling has even been linked to early Parkinson’s.
So while we may not yet know why we evolved this trait, our pruney fingertips are revealing far more than we once imagined.
Courtesy: BBC
Bd-pratidin English/FNC
