Column: Dr's Casebook" Dr Keith Souter: What Do Those Wrinkled fingers and Toes Mean?
I just spent a week on the Isle of Wight, walking and swimming. The beaches are so clean and the water was so clear that I spent a lot of time in the water. It was partly because it was so hot, but I also wanted to do a little experimentation to see whether I could confirm some research I had read about skin wrinkling.
The research was from Binghamton University in New York. The question had been posed as to why your fingers and toes go wrinkly after staying in the water too long. Up until then it was thought that the water swells the skin and thereby produces the wrinkling, but no research had actually been done.
The researchers at the Biological Soft Matter Mechanics Laboratory found that blood vessels beneath the skin actually contract after prolonged immersion, and that's where the wrinkles come from.
But the further question was posed as to whether the skin wrinkles in the same way every time. Blood vessels are anatomical structures so you wouldn’t expect them to change position very much. The tiny blood vessels under the skin can move, but not greatly. And indeed, when they did experiments on students who were asked to immerse their hands in water for a prolonged time on different occasions, each time being photographed, they found that the pictures showed exactly the same pattern of wrinkling.
I thought that would be a fun think to try out myself and so after three days of swimming in the sea, each one separated by a day’s walking and not swimming to allow the skin to recover, I photographed the wrinkling on my fingers and toes. And lo and behold, the patterns matched exactly. The same loops and ridges appeared in the same places.
So, it seems that the skin blood vessels contract and cause the wrinkles. The paper I read had an interesting incidental finding, in that one of the students had a median nerve damage in his fingers and his fingers did not wrinkle. It would seem that the blood vessel contraction under nerve control is a factor. It may be that people with nerve damage to areas of skin may not wrinkle.
The research team speculate that this finding could have important implications in forensic science. For example, fingerprinting at crime scenes and identifying bodies found after prolonged water exposure.