Question: Why do humans get wrinkly when they stay in water for a while?

Richard Unwin answered on 16 Nov 2015:

A brilliant question – with a surprising answer! I always though that it’s because, if we spent long enough in the water, we washed away the ‘waterproof’ covering on our fingers and then water enters our cells and they swelled slightly, causing the skin to wrinkle but that’s NOT true.
In the 1930s scientists found that people who had nerve damage and no feelings in their fingers did NOT get wrinkly skin, telling us that it’s a reaction to the water by our own body causing the skin to wrinkle by causing blood vessels to constrict. It was shown a couple of years ago that wrinkly fingers are then much better as picking up wet objects that dry, smooth fingers are – with the wrinkles acting like the tread on a car type and allowing a better grip.
So the answer is, it helps us to pick up wet objects when we’re in water!