Previously it was thought that the upper layers of the skin by absorbing water and therefore is wrinkles.
However, this hypothesis does not explain why the skin will be is wrinkled only at the tips of the fingers and toes. In addition, in case of violation of the innervation of the skin wrinkling was not observed. Experiments showed that the water a contact with limbs causes vasoconstriction lower layers of the skin. This leads to a decrease in the area of the lower layer of the skin. Lower skin layer pulls behind itself a more the top layer, forming wrinkles thereon. That is all happening exactly the opposite than previously thought.
But why this effect is observed only on a finger skin? It turned out that the mechanism is the result of evolution. In wet weather, due to a thin layer of water deteriorates the contact with surfaces. Therefore, the foot will slide, things will slip out of hand. But after a few minutes are formed the folds, which is by drainage channels, water is removed quickly and increasing clutch.
This principle is used in the development of all-weather tires, which exclude aquaplaning. See how different tires for dry and wet asphalt of Formula 1 cars:
It is necessary to develop a tire that adapts to the weather, as skin.
