Why Fingers Wrinkle When They Get Wet

August 16, 2011

Interview with Mark Changizi, author of the book Harnessed: How Language and Music Mimicked Nature and Transformed Ape to Man

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Mike Carruthers:
Humans have excellent color vision and it’s long been thought we have that to help us find food in the wild in order to survive.

Mark Changizi:
And I was able to provide evidence that “no” your color vision is in fact really peculiar and it’s turned out to be optimized for seeing blood in the skin.
 

Mark Changizi, author of the book Harnessed...

When you blanch and blush in your face you have all the kinds of facial color changes that happen as your emotion change but to see those color changes you have to have special kind of color vision in order to capture it. And we have exactly the kind of color vision to allow us to see that – so color at the end of the day in primates is really all about emotions and the moods of others in our midst.

Ever wonder why your fingers get wrinkled when they get wet?

Traditionally people think that it’s due to some kind of natural physical reaction to what happens when water hits your fingers. Of course the rest of your body doesn’t wrinkle when it’s wet so it’s not clear why that would make sense in the first place and also when water absorbs in something it typically makes it swell not get wrinkly. The story is if you’re a primate then when it would rain grip is very important.  And when you’re reaching out and griping things if it’s wet then you’ll hydroplane unless you have the right kind of treads.

So the theory is your fingers wrinkle to create treads.

What we did is we worked out what would the optimal channel shapes be and in fact when we worked it out and then we tested real wrinkled fingers of all the infinitely many possible wrinkles that they could have they have the wrinkle shapes that match what you’d expect if these things are in fact treads.

To hear the complete unedited interview, click here