This is an urban myth: scans show that most of the brain is active even when we’re not doing much. It’s true that brains are adaptable, and we have huge potential to learn new skills, but this happens mostly via the formation of new connections and networks in the brain, not through the activation of previously idle areas.
The brain is a huge energy-guzzler, and it wouldn’t make sense for us to have evolved to use a fraction of such a costly organ.
Dr Christian Jarrett is a cognitive neuroscientist, science writer and author. He is the Deputy Editor of Psyche, the sister magazine to Aeon that illuminates the human condition through psychology, philosophy and the arts. Jarrett also created the British Psychological Society's Research Digest blog and was the first ever staff journalist on the Society's magazine, The Psychologist. He is author of Great Myths of The Brain and Be Who You Want: Unlocking the Science of Personality Change.