Have you ever wondered why yawns are contagious? Why bubble wrap is so fun to pop? And how is it that Justin Bieber's face can immediately make people dry heave and go into shock? So many of life's important questions go unanswered.
But, well, a recent study using mice has unraveled one of life's more low-level, yet curious, mysteries: what is an itch and why do we scratch? Gizmodo reports that the act of scratching is actually a defense mechanism that protects our skin from "objects in the environment or nasty insects and parasites." When we scrape across our skin with our fingernails, we try to kill whatever's disrupting our vibe. What causes the itch, though, is a molecule found in the heart, called the natriuretic polypeptide b, (Nppb) which sends a message to our spinal cords when something is irritating or dangerous enough to warrant a physical response.