If this 10 percent idea were somehow true, how could the other 90 percent of your brain cells have gotten there in the first place? How could we be carrying around a 1.4-kilogram (3.1-pound) organ and not use 90 percent of it? Well, it wouldn't be reasonable from an evolutionary
In the economics of biology, it's expensive to have a brain. We are animals on Earth. We came to be in the same worldwide ecosystem as everybody and everything else -- our fellow earthlings, eels, dolphins, giraffes, sea jellies and the like. As a run-of-the-Earth organism, you have to spend the metabolic energy to grow your brain, and you have to expend calories -- as much as 30 percent of all the calories you consume -- to maintain it. That would be all while you're dodging lions, tigers and bears, for example, let alone the challenges from members of your own species for access to food and a mate.
So if you were to let 90 percent of the energy you spend on brain matter go to waste, that would make you seem, if I may, at least 90 percent out of your mind. And, it's the potential for wasted brainpower that may be at the heart (er, the brain) of your question -- of this matter -- the gray matter (ha!).
The myth that we're not using such a vast amount of our brains may stem from our fear that we aren't thinking hard enough. Haven't you felt from time to time that you would be better off if you could just think more or think better? Maybe you could
become "super-smart" if you could just figure out how to use that dormant part of your brain.