A scientific debate has recently emerged about why our fingers wrinkle. On one side: osmosis loyalists. On the other: researchers who believe pruning is a neural mechanism to improve traction - to make your hands more grippy when they're wet.
For many years, most people assumed that our fingers and toes took on the texture of raisins from absorbing water - the longer you soaked in the tub, the more wrinkly your extremities. These rogue theorists instead suggest the grooves in wet fingers push out water when pressed to surfaces, allowing for better contact (and thus, better grip). To their point, previous research shows people with severed nerves in their fingers don't prune up in water - showing that wet, wrinkly hands and feet are a product of the nervous system.
Sounds reasonable! The problem is that these researchers haven't done much, uh, research to prove their theory is entirely legit. They're working on it. But in the meantime: don't run through puddles by the pool. No matter how smart our nervous system is, you'll probably still slip and fall on your arse. [Discovery News]