Most people think this is due to the water being absorbed by the skin, causing it to swell and change its shape. But new research shows that severing the finger nerves will make the swelling and wrinkles disappear. In light of this discovery, researchers have come up with a new theory : the fingers don’t actually swell, but instead they get narrower due to the constriction of the blood vessels.
This is basically the effect of the human body adapting to its environment., and it stems from early human evolution.
The nervous system sends out the signal you are no longer in a dry environment, much like it does in other situations such as stress, fear or darkness.
It seems that the wrinkles on your fingers will actually make your hands function better in water, providing more adherence. This improves your grasp, but also your swimming skills as you dash through the water with more power.
The same thing applies to wrinkled toes, which are especially efficient when running on muddy, slippery soil.