Why Do Fingers And Toes Wrinkle In The Bath?

Ever sat in the bath for a little too long only to find that your fingers and toes start to look less like fingers and toes and more like wrinkly little raisins? Mmm tasty.

The wrinkly raisin effect happens after about ten minutes of being submerged in water - whether that's doing the washing up, swimming or soaking in the tub - and happens to (almost) all of us.

Once upon a time scientists believed the prune-like appearance was caused by osmosis. They said an influx of water made the outer layer of skin to swell up causing it to pucker.

In the 1930s this theory was disproven when doctors observed that patients with nerve damage did not pucker at all. They soon discovered that the prune-like symptoms were linked to the nervous system and blood vessels constricting below the skin.

But do wrinkly fingers have any function apart from looking really, really weird?

Well, yes, recent studies suggest that prune-like fingers may have served an evolutionary function - helping us grip while sourcing food in wet conditions or walking barefoot along wet surfaces.

In a recent study, participants picked up wet or dry objects with normal hands or with wrinkly fingers that had been soaked in water for 30 minutes.

Scientists found that people with wrinkly wet hands were able to pick up wet objects 12% faster than people with dry hands.

"We have shown that wrinkled fingers give a better grip in wet conditions — it could be working like treads on your car tyres, which allow more of the tyre to be in contact with the road and gives you a better grip," says Tom Smulders, an evolutionary biologist at Newcastle University and a co-author of the paper.

“Going back in time this wrinkling of our fingers in wet conditions could have helped with gathering food from wet vegetation or streams.

“And as we see the effect in our toes too, this may have been an advantage as it may have meant our ancestors were able to get a better footing in the rain.”

[H/T Buzzfeed and Sci Show]