Why do our fingers wrinkle when wet?

Gemma Hallam

Look familiar?

Now you’re home from student accommodation you may have re-established access to a bathtub! And there’s nothing better than a steamy, relaxing wallow to cheer us up from this ghastly downpour, which is invading our ‘summer’ break. But upon finally emerging, you look down at your hands and feet and wonder at what point your appendages were replaced with those of an old lady!

Layers of the skin

What happens is the outer layer of skin (the epidermis) absorbs a little bit of water and expands. The layer underneath (the dermis) doesn't do this and so the skin on top buckles – folding in places – leading to the wrinkly digits we’re all so familiar with. The skin on our hands and feet is thicker than on the rest of the body and so the changes here are noticeable whereas the rest of our braised bods appear to have remained less than 80 years old!

'Wrinkle drainage'

Another idea was recently forwarded that suggested ‘pruney’ fingers are an adaptation to help humans and other primates grip in wet conditions. In this theory the wrinkles act like rain treads on tyres allowing water to drain through channels when we press our fingertips on a wet surface.

Functional or unintentional it is certainly a relief when our hands dry and return to normal!

For more information on the current theories check out this link - Are Wet-Induced Wrinkled Fingers Primate Rain Treads?