Why do fingers wrinkle in water?
Fingers wrinkle in water because the nervous system narrows blood vessels under the skin, making it pucker. Scientists think the wrinkles may help us grip wet objects.
For a long time, people thought fingers wrinkled simply because skin absorbs water and swells. But doctors noticed that fingers with damaged nerves do not wrinkle, which showed that the nervous system controls the effect.
When hands soak for about five minutes or more, nerves signal blood vessels in the fingertips to constrict. The soft tissue under the skin shrinks slightly and the outer skin folds into ridges. The effect fades once the hands dry.
Built-in tire treads?
A 2013 study found that people with wrinkled fingers moved wet objects faster than those with smooth fingers, suggesting wrinkles channel water away like tire treads. Other studies have not always confirmed this, so the purpose is still debated.
Doctors sometimes use the water-wrinkle test to check nerve function in the hands, because fingers with damaged nerves stay smooth after soaking.
Did You Know?
Wrinkling happens mainly on the fingers and toes, the parts that touch wet surfaces when walking or gripping.
This answer is general information, not medical advice. For a personal health question, talk to a doctor.