Why do our fingers wrinkle when wet?

Ready to have your mind blown? For a long time, scientists thought that our fingers wrinkled underwater because of osmosis — meaning the skin's cells absorbed water, causing our fingertips to shrivel up. But new research suggests another explanation for why our digits suddenly morph into raisins when wet: The wrinkles help us to better grip objects underwater, in much the same way tire treads help cars stay on the road.

Scientists were tipped off in recent years when they discovered that severed fingers didn't wrinkle underwater. This suggested the wrinkling mechanism was controlled by the nervous system, and was therefore some kind of evolutionary response.

A study in 2011 showed that the wrinkles indeed functioned like rain treads, in that the grooves helped divert water away from the fingertips. For this study, researcher Tom Smulder and his team at Newcastle University in the U.K. asked subjects to move wet and dry objects from one box to another with and without shriveled fingers. Unsurprisingly, people with wrinkled hands transferred objects 12 percent faster than those with smooth digits.

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As to why our fingers aren't wrinkled at all times, Smulders says it may have something to do with maintaining our fingertips' sensitivity. Amazing stuff. The human body, ladies and gentlemen.