The human brain is basically the ultimate supercomputer, but despite all the science we have today, there are still a ton of wild rumors circulating about how it works.
Here is the ultimate fact-check on the biggest brain myths—serviced with real receipts and quotes from top researchers.
Myth 1: You Only Use 10% of Your Brain
You’ve definitely heard this one in sci-fi movies or random social media threads claiming that if you could just unlocked the other 90%, you’d instantly get telepathic powers or superhero intelligence.
Reality Check
Neuroimaging shows that 100% of your brain is active—even while you’re sleeping. If 90% of your brain were useless, minor head injuries wouldn’t carry such huge risks. In reality, even tiny damage to small brain regions can severely impact your cognitive ability.
“It turns out though, that we use virtually every part of the brain, and that [most of] the brain is active almost all the time. Let’s put it this way: the brain represents three percent of the body’s weight and uses 20 percent of the body’s ene
rgy.” — Dr. Barry Gordon, Neurologist at Johns Hopkins School of Medicine (via Scientific American)
Myth 2: Brain Damage Is Always Permanent
There’s a lingering idea that once your brain takes a hit or suffers an injury, those neural pathways are permanently glitched with zero chance of recovery.
Reality Check
While severe injuries can leave lasting effects, the brain is absurdly resilient thanks to neuroplasticity—its ability to rewire itself, build new pathways, and adapt around damaged areas over time.
“Even after more serious brain injury, such as stroke, research indicates that — especially with the help of therapy — the brain may be capable of developing new connections and ‘reroute’ function through healthy areas.”
— BrainFacts.org
Myth 3: You’re Either “Left-Brained” or “Right-Brained”
People love to self-diagnose: “I’m super analytical, so I must be left-brained,” or “I’m an artist, so I’m strictly right-brained.”
Reality Check
While certain hemispheres take the lead on specific sub-tasks (called lateralization), you don’t have a “dominant side.” Complex thinking, creativity, and logic require both hemispheres working together seamlessly through a massive neural highway called the corpus callosum.
“No matter how lateralized the brain can get, though, the two sides still work together. The pop psychology notion of a left brain and a right brain doesn’t capture their intimate working relationship… The left hemisphere specializes in picking out the sounds that form words and working out the synta
x… but the right hemisphere is actually more sensitive to the emotional features of language…” — Carl Zimmer (via Discover Magazine)
Myth 4: Humans Have the Biggest Brains
It’s easy to assume that because humans dominate the planet intellectually, we must carry around the largest brains in the animal kingdom.
Reality Check
An adult human brain weighs about 3 pounds. A sperm whale’s brain weighs a massive 18 pounds, and an elephant’s brain sits at around 11 pounds! Even if you look at brain-to-body mass ratio, the tiny tree shrew takes the crown, with its brain taking up 10% of its entire body weight (compared to humans at ~2–3%).
“The Encephalization Quotient (EQ) is a measure of brain size relative to body size. The cat has an EQ of about 1… while chimps have an EQ of 2.5 and humans nearly 7.5. Dolphins… have an EQ of more than 5, but rats and rabbits are way down on the scale at below 0.4.”
— Michael Balter (via Slate.com)
Myth 5: You Stop Growing New Brain Cells as an Adult
For a long time, the prevailing belief was that you’re born with all the brain cells you’ll ever get, and from adulthood on, it’s a strict downward slope.
Reality Check
Your brain continues generating brand-new neurons throughout your entire adult life through a process called neurogenesis, particularly in the hippocampus (the hub responsible for learning and memory).
“Above-ground nuclear bomb tests carried out more than 50 years ago resulted in elevated atmospheric levels of the radioactive carbon-14 isotope… In a study published yesterday in Cell, researchers used measurements of 14C concentration in the DNA of brain cells… and demonstrated that there is substantial adult neurogenesis in the human hippocampus.”
— Dan Cossins (via The Scientist)
Myth 6: Drinking Alcohol Flat-Out Kills Brain Cells
We’ve all heard warnings that a night out or casual drinks will straight-up destroy thousands of irreplaceable neurons.
Reality Check
Excessive or chronic alcohol abuse can damage the connections between neurons (dendrites) and cause health issues, but drinking doesn’t actually kill brain cells directly. In fact, moderate drinking studies show no evidence of neuron death.
“Scientific medical research has actually demonstrated that the moderate consumption of alcohol is associated with better cognitive skills and memory than is abstaining… Moderate drinking doesn’t kill brain cells but helps the brain function better into old age.”
— Dr. David J. Hanson (via PsychCentral.com)
Myth 7: The Human Brain Has Exactly 100 Billion Neurons
Almost every old biology textbook parroted the clean, round figure of 100 billion neurons.
Reality Check
For decades, nobody had actually counted them precisely. In 2009, neuroscientist Dr. Suzana Herculano-Houzel developed a new counting method and discovered the real average is around 86 billion neurons. While 14 billion might sound like a small rounding error, that difference is equivalent to an entire baboon brain!
“We found that on average the human brain has 86bn neurons. And not one [of the brains] that we looked at so far has the 100bn… the 14bn neurons amount to pretty much the number of neurons that a baboon brain has or almost half the number of neurons in the gorilla brain.”
— Dr. Suzana Herculano-Houzel (via The Guardian)
Original Article References
- Balter, M. (2012, Oct. 26). Why are our brains so ridiculously big? Slate. Retrieved from http://www.slate.com/articles/health_and_science/human_evolution/2012/10/human_brain_size_social_groups_led_to_the_evolution_of_large_brains.html
- Boyd, R. (2008, Feb 7). Do people only use 10 percent of their brains? Scientific American. Retrieved from http://www.scientificamerican.com/article.cfm?id=people-only-use-10-percent-of-brain
- BrainFacts.org. (2012). Myth: Brain damage is always permanent. Retrieved from http://www.brainfacts.org/diseases-disorders/injury/articles/2011/brain-damage-is-always-permanent
- Cossins, D. (2013, June 7). Human adult neurogenesis revealed. The Scientist. Retrieved from http://www.the-scientist.com/?articles.view/articleNo/35902/title/Human-Adult-Neurogenesis-Revealed/
- Herculano-Houzel S (2009). The human brain in numbers: A linearly scaled-up primate brain. Frontiers in Human Neuroscience, 3(31). doi:10.3389/neuro.09.031.2009 Randerson, J. (2012, Feb 28).
- How many neurons make a human brain? Billions fewer than we thought. The Guardian. Retrieved from http://www.guardian.co.uk/science/blog/2012/feb/28/how-many-neurons-human-brain The Technium. (2004).
- Brains of white matter. http://www.kk.org/thetechnium/archives/2004/11/brains_of_white.php Zimmer, C. (2009, April 15).
- The Big Similarities & Quirky Differences Between Our Left and Right Brains. Discover Magazine. Retrieved from http://discovermagazine.com/2009/may/15-big-similarities-and-quirky-differences-between-our-left-and-right-brains
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