Wrinkles that form on our fingers and toes when underwater could be an evolutionary adaption that allows us to manipulate objects more easily.
Fingers and toes wrinkle in water after about 5 minutes due to the constriction of blood vessels. This reduction in volume pulls the skin inward, but as the skin’s surface area cannot change, it wrinkles. A study in 2011 showed that wrinkles form a pattern of channels that divert water away from the fingertip — akin to rain treads on tires. The team thought that this could aid grip.
To find out, Tom Smulders and his team at Newcastle University, UK, timed people as they transferred wet or dry objects from one box to another with and without wrinkled fingers. With wrinkles, wet objects were transferred about 12 percent faster than with unwrinkled fingers. The time it took to transfer dry objects was the same regardless of wrinkles (Royal Society Biology Letters).
So why aren’t our digits always prune-like?
–Â Helen Thomson
