Uncle John knows pretty much everything—and if he doesn’t, he heads his massive research library, or puts one of his many associates on the case. So go ahead: In the comments below, ask Uncle John anything. (And if we answer your question sometime, we’ll send you a free book!)

Do humans really only use 10 percent of their brains?

While watching TV this past weekend, Uncle John was bombarded with previews for a new action movie called Lucy. The promo begins with a voice over by Morgan Freeman stating that “humans use only 10 percent of their brains” before introducing us to a superhuman experiment named Lucy (Scarlett Johansson) who has been modified to use all of her brain, and boy is she dangerous.

Uncle John just about threw the remote at the TV—Hollywood made a whole movie based on a widespread myth, or misconception, or “myth-conception” that just won’t die. It’s simply not true that humans use only 10 percent of their brains.

The brain is a vastly complicated and intricate network of cells, neurons, and activity that keeps the equally complicated and intricate human body working. And it’s a relatively tiny control center, weighing no more than three pounds. It has to be extremely efficient for you to breathe, pump blood, digest food, and waste time on the Internet all at once. Each part of the brain has a very specific function, and researchers have never found a part of the brain that was dead weight or “unused” gray matter.

The myth probably stems from the innocuous fact that only about 5 to 10 percent of the brain’s neurons are active at any given time. This means that 10 percent of your brain is used for thinking; the rest is still conducting bodily business without you having to think about it.