I was at a conference recently where someone with a degree in science repeated the erroneous claim that humans use 10 per cent of their brains. I was shocked that someone with scientific training would make such a statement and I wondered both about the quality of the science degree and about this person’s ability to think critically.

What is the origin of this fallacious claim? William James wrote in The Energies of Men (1907) that “We are making use of only a small part of our possible mental and physical resources.” (Some believe that Einstein commented on this myth, attributing his intellectual gifts to using more than 10 per cent of his brain. There is no evidence he made such a statement.)

That was over 100 years ago, when we knew less about the human brain than we know now, yet this 10 per cent myth endures. Why?

Perhaps it’s the desire to believe that we have untapped potential, waiting for the next evolutionary step or unlocking of superhuman abilities. That by employing a greater percentage of our grey matter, humans will become telepaths and telekinetics (of course, laws of nature will also have to be suspended). Paranormal piffle one hears as money is drained from one’s wallet. Fantastical stuff, but not rooted in reality.

There may be people who seem to use 10 per cent or less of their brains, but every part of the brain is active nearly all the time. Imaging technology has found that 100 per cent of the brain is used over a 24-hour period. Even during sleep, the brain is active, just in a different state than when humans are awake.

In addition to evidence found in imaging technology if only 10 per cent of the brain were in use, then 90 per cent of the brain could sustain damage without loss of normal functioning. However, most areas of the brain, if damaged, result in varying degrees of impairment.

There’s also evolution. The brain is an energy-intensive organ; a three-pound metabolic monster consuming nearly 20 per cent of the body’s energy in the form of oxygen and glucose. If 90 per cent of the brain were extraneous, then Homo sapiens would not have evolved with the cranial capacity it has today; natural selection would favour smaller, more efficient brains.

I applaud anyone who strives to exercise her/his brain; who wants to learn more, read more, employ critical thinking more. Indeed, if we devote time to cultivating reason, nonsense like the 10 per cent brain myth would whither away.

Eric Mang

Eric Mang

Eric Mang served as a political aide in the Harris government in Ontario and the Campbell government in British Columbia. His politics have since shifted left. He works full-time in health policy, part-time...