Après Bath, by Sharon Drummond
I have often wondered this. Now there’s a study in Brain, Behavior and Evolution that says the reaction may be adaptive – our fingers get wrinkly to help us grip in wet conditions. Like tires with tread. Very interesting.
Apparently as early as 1935 they discovered that fingers didn’t get pruney if there was nerve damage. Hence, there was some software running here, it wasn’t just a hardware glitch. Still, it was always a mystery to me.
Then I read the piece by Mark Changizi, Romann Weber, Ritesh Kotecha, Joseph Palazzo… breath… and it all made a bit more sense. Especially the part where they compared it to treads on a tire.
Wet-induced wrinkles may, in fact, be substantially superior to ‘rain treads’ on shoes, which maintain a tread even when under compression and thus have a surface area of contact that is reduced. Wet-induced wrinkle treads, on the other hand, are pliable, and the act of pressing a finger tip down on a wet surface ‘squeezes’ the fluid out from under the finger through the channels, and upon completion of this single pulsatile flow the entire finger’s skin contacts the surface.
They also compared it to drainage patterns in river basins. Very interesting stuff. Worth a read.