Science figured out why our fingers and toes get all wrinkly when we spend time in the water.
Basically, it's because our bodies accept that we want to be merpeople, and adjust accordingly.
OK, so that's probably not quite how evolutionary scientists would put it. But those grooves in our fingers that make them look like raisins actually do serve a purpose: Wrinkly fingers make it easier for us to grip slippery or submerged objects.
Basically, our finger wrinkles act like the rain treads on tires to channel away water so we can hold onto something.
Scientists first got a clue that prune fingers served a purpose when they observed that the effect doesn't happen if there's nerve damage to the fingers.
That means the reaction is an involuntary one controlled by the body's autonomic nervous system — the same system that controls breathing and your heart rate. The wrinkled look is caused by blood vessels constricting beneath the skin.
Scientists knew that, because the wrinkling was this kind of function, there must be an evolutionary reason behind it. But for years, no one had conducted a study proving that wrinkly fingers really did improve grip.
Finally, a study had two groups of people pick up wet marbles with dry hands, or after soaking their hands in water for 30 minutes. The prune hands won!
The researchers believe this feature originally evolved to help humans gather food from wet vegetation or streams.
Wrinkled toes may have helped humans walk in the rain before rain boots came along.
If our fingers work so much better when they're wrinkly, why aren't they permanently wrinkled? Scientists aren't sure, actually. They're also interested in looking into what other animals turn prune-y. So far, it's just us and macaques.
So this summer when you're hanging out in the water and you see those telltale wrinkles, know that your raisiny hands are actually better equipped than ever to catch the stray Frisbee, volleyball or whatever life may toss your way.