Recently, I saw the movie Lucy starring Scarlett Johansson and Morgan Freeman. If you’re planning on watching it and don’t want me to spoil it for you, then skip the next paragraph. (In my opinion, you can find plenty of better ways to spend 89 minutes.)

The general story is that a college student studying abroad (Johansson) gets abducted by a gang in Taipei and is forced to carry a bag of drugs that they implant in her abdomen. When the bag starts leaking its contents, CPH4 (based on a real molecule that pregnant woman produce which the movie likens to an “atomic bomb for a fetus”), the drug triggers rampant production of new connections between neurons giving Lucy access to the 90 percent of her brain that supposedly most of us never use.

The explosive brain growth makes her superhuman, and levitation, time travel, mind reading, learning Chinese in an instant, mentally controlling electronics, altering and generating new body parts, as well as high-speed car chases, and fight-to-the-death scenes follow.

Lucy is based on a lie

The director, Luc Besson, knew the idea that we only use 10% of our brain power was wrong but went with it anyway. Hey, it IS science fiction. I get it, but the problem is that too many people accept this brain myth as a fact. According to a TED-Ed Animation, two-thirds of the public and nearly half of all science teachers still mistakenly believe this nonsense.

There’s absolutely no truth to the idea that we only use 10% of our neural matter.

The Battle In Your Brain

It’s true that increased connectivity between neurons is associated with greater ability. Studies have shown that musicians, who play stringed instruments, have larger areas of their brains dedicated to their active hands. Brain scans of London taxi drivers have revealed that the more years a driver has on the job correlates to a larger portion of their brain being recruited to store spatial information.

These findings demonstrate Hebb’s law: neurons that fire together wire together and neuroplasticity, the ability of the brain to change its physical structure and function based on repeated experience, behavior, and thoughts. In the blog, The Battle In Your Brain, I write:

Every minute of every day there’s a battle going on in your brain — a battle for cortical real estate. Your experiences, behaviours, emotions, and even your thoughts are constantly, literally changing and shaping your brain.

You have a use or lose it brain. Any unused connections go dormant to free up resources needed to strengthen those connections that are most often used. Neuroplasticity is competitive, and functioning areas of the brain not receiving any stimuli will be quickly taken over. In experiments where participants were blindfolded, their visual cortices started reorganizing themselves to process sound in just two days!

You Already Use 100% Of Your Brain

Brain scans show activity coursing through your entire brain all the time, even at rest and during sleep. Not all 86 billion neurons are firing at once, of course, but they do exist in a constant state of resting potential, electrically charged, ready to act when needed.

An article in Scientific America, “Do People Only Use 10% Of Their Brains,” explains:

‘Evidence would show over a day you use 100 percent of the brain,’ says John Henley, a neurologist at the Mayo Clinic in Rochester, Minn. Even in sleep, areas such as the frontal cortex, which controls things like higher level thinking and self-awareness, or the somatosensory areas, which help people sense their surroundings, are active, Henley explains. ….’ the brain is active almost all the time’

Your Brain Is An Energy Hog

Your brain is incredibly hungry and requires a huge amount of energy just to keep running. The human adult brain makes up about only 2% of the body’s mass yet uses 20% of energy intake. In children, the brain eats up 50% of daily glucose intake, and infant’s brains take a whopping 60%.

Brain sizes scale in proportion to body size with larger animals having larger brains, but on a per weight basis, humans pack in more neurons than any other species. This density is what makes us so smart. It takes an awful lot of fuel to power that complex brain, and there’s a trade off between body size and sustainable number of neurons. According to the Ted-Ed Animation, “A 25 kilogram ape has to eat 8 hours a day to uphold a brain with 53 billion neurons.”

The invention of cooking food gave humans the means to power their growing brains because our guts could more easily absorb energy from cooked food.

Our brains also adapted by learning to become incredibly energy efficient. At any one time, only a small proportion of brain cells are signaling, a process known as “sparse coding”, allowing the brain to use the least amount of energy while transferring the most information. The need to conserve energy resources is the reason that most brain processes happen below conscious awareness and that multitasking just doesn’t work. There’s not enough energy available to the brain to focus on more than one thing at a time.

The energy burden of maintaining an activation spike over the entire brain at once would be unsustainable. So, using the brain at full capacity all the time, like depicted at the end of the movie, would be impossible. A person simply could not supply the necessary fuel.

Smart Drugs

Another movie, Limitless, portrayed a disheveled writer who cleaned up his life and at the bank when he discovered and became addicted to a cognitive enhancing “smart drug.” While some neuroenhancers or nootropics do actually exist today, a wonder drug as portrayed in both movies has yet to be discovered.

In a BBC News article, Professor John Harris, director of the Institute for Science, Ethics, and Innovation at The University of Manchester, says smart drugs can give people an edge, but:

They have a similar effect to hard work and coffee. Physical exercise also has the same effect. They are all, to an extent, cognitive enhancers. If you’re not a genius before, you won’t be afterward.

The Scientific America article concludes by saying,

Ultimately, it’s not that we use 10 percent of our brains, merely that we only understand about 10 percent of how it functions.