JASMA

Humans love a good story. Unfortunately, we also love bad facts. Some “truths”
have hung around so long that they feel more permanent than your student loans:
chew gum and it lives in your stomach for seven years, bats are totally blind,
and obviously you only use 10% of your brain (so… what’s the other 90% doing,
scrolling social media?).

In this Listverse-style deep dive, we’ll tackle yet another 10 commonly believed
myths, look at where they came from, and see what real science has to say.
Expect a mix of gentle roasting, actual research, and a few “wait… what?” moments.

1. “We Only Use 10% of Our Brains”

Why people believe it

This myth is the motivational poster of neuroscience. Self-help books,
inspirational speakers, and even sci-fi movies like Limitless and
Lucy have pushed the idea that you’re walking around with a super-computer
in your skull and only using a tiny sliver of it.

What science actually shows

Neuroscientists have been politely screaming into the void about this one for years.
Brain imaging studies show that we use virtually every part of the brain
over the course of a dayjust not all at the same exact moment. MIT researchers
point out that even simple tasks engage multiple regions, and there’s no huge
“dark” chunk of brain sitting idle, waiting for a subscription upgrade.

The “10%” figure doesn’t come from legitimate experiments; it likely grew out of
early, vague comments about human potential that got oversimplified, misquoted,
and endlessly repeated. The reality is less magical but more impressive: your brain
is already running near full capacity just keeping you alive, thinking, moving,
feeling, and remembering where you put your phone (most of the time).

2. “The Great Wall of China Is the Only Man-Made Structure Visible from Space”

Why people believe it

Schoolbooks, trivia games, and random internet posts have turned this into a
default “fun fact”: astronauts can see the Great Wall from space, and it’s the
only human structure visible. It sounds grand, poetic, and extremely
shareable… which is usually a red flag.

What science actually shows

Space agencies and astronauts have repeatedly debunked this. The Great Wall is
relatively narrow and built from materials that blend in with the surrounding
landscape, making it hard to spot with the naked eye from orbit. Under certain
perfect conditions and with powerful lenses, parts of it can be seen from low
Earth orbitbut so can highways, airports, and even long bridges.

One analysis of human visual limits and orbital distance concluded that even
“the best of human eyes” couldn’t see it as a distinct object without help.
So yes, it’s an incredible feat of engineeringbut not a magical stone neon sign
visible from the Moon.

3. “Sugar Makes Kids Hyper”

Why people believe it

Picture a child at a birthday party, frosting all over their face, sprinting in
circles and screaming like they just drank espresso. Adults look at the cake and
sugary drinks and think: “Yup, that’s the sugar talking.”

What science actually shows

Controlled studies going back decades have found no consistent link between sugar
intake and hyperactivity in children. Reviews of the research show that kids who
eat sugar don’t behave significantly differently than kids who get placebos, even
when parents are sure they see a difference.

So what’s going on? Context. Parties are exciting. Kids are around friends,
they’re staying up late, there’s loud music, games, and general chaos. Parents
also tend to expect misbehavior after sugar, which can change how they interpret
normal kid energy. Recent coverage by outlets like National Geographic
and pediatric centers notes that the “sugar rush” is largely a perception, not a
physiological certainty.

Is unlimited sugar a good idea? Definitely notthink teeth, weight, and long-term
health. But if your child is bouncing off the walls, the frosting is probably not
the only thing to blame.

4. “Cracking Your Knuckles Causes Arthritis”

Why people believe it

That loud pop from your fingers sounds… ominous. Many parents and grandparents
have warned that if you keep cracking your knuckles, you’ll “get arthritis” or
ruin your hands. It feels like a fair trade threat: stop that noise, or face
joint doom.

What science actually shows

Medical reviews and longitudinal studies haven’t found a higher rate of arthritis
in chronic knuckle-crackers compared with non-crackers.
Johns Hopkins rheumatology experts and other arthritis specialists agree: the
cracking sound is usually gas bubbles collapsing in the joint fluid, not bones
grinding or cartilage shattering.

That said, excessive knuckle cracking might be linked to slightly reduced grip
strength or soft-tissue irritation in some people, and it can definitely irritate
the people around you. So the main risk is social, not skeletal.

5. “Vaccines Cause Autism”

Why people believe it

This myth is one of the most harmful on this list. It gained momentum after a
now-retracted study in the late 1990s claimed a link between the MMR vaccine and
autism. Media coverage, online communities, and understandable parental anxiety
helped the idea spread worldwide.

What science actually shows

Large, well-designed studies across multiple countries involving millions of
children have found no causal link between vaccines and autism.
Institutions like major children’s hospitals and vaccine education centers
emphasize that early research used to support the myth was flawed or fraudulent,
and subsequent data simply doesn’t back it up.

Autism is complex and likely involves a combination of genetic and environmental
factors, but vaccines are not one of them according to current evidence. Choosing
to skip vaccination, however, has very clear risks: outbreaks of measles,
whooping cough, and other preventable diseases return when vaccination rates drop.

It’s important to be compassionate here. Many parents who worry about vaccines
are trying to protect their children. The goal isn’t to mock their fear, but to
point them toward the best available science.

6. “Goldfish Have a 3-Second Memory”

Why people believe it

Goldfish have become the unofficial mascots of forgetfulness. Jokes, cartoons,
and casual conversation use “memory of a goldfish” to describe someone who can’t
remember anything for more than a moment.

What science actually shows

Multiple experiments have demonstrated that goldfish can remember information for
weeks, months, and even years. They can be trained to respond to sounds, navigate
mazes, and remember feeding locations.

Educational and science outlets have highlighted studies where goldfish improved
on tasks over several days, clearly showing that their memory lasts far longer
than a few seconds.
The “3-second memory” line is catchy, but it seriously undersells these little
swimmers.

So if your goldfish stares at you when you walk past the tank, it might not be
confused. It might just be thinking, “Oh good, the food human.”

7. “Bats Are Blind”

Why people believe it

The phrase “blind as a bat” is baked into the language. Because bats fly at night,
use echolocation, and generally give off spooky after-dark vibes, people assume
their eyes don’t work or don’t exist in any meaningful way.

What science actually shows

Bats are not blind. In fact, many species have good visionsome can even see
ultraviolet light.
Organizations that specialize in bat conservation note that all bats have
functional eyes, and larger fruit bats may see several times better than humans
in low-light conditions.

Echolocation is an extra superpower, not a replacement for eyesight.
Bats combine sound and vision to navigate and hunt. If anything, “blind as a bat”
should probably be replaced with “multitasking like a bat.”

8. “Everyone Needs to Drink 8 Glasses of Water a Day”

Why people believe it

“Drink eight 8-ounce glasses of water a day” is the Beyoncé of health tips
constantly on tour, endlessly repeated, and rarely questioned. It’s simple,
easy to remember, and sounds very official.

What science actually shows

Hydration experts and medical organizations say there’s no solid scientific basis
for a one-size-fits-all “8x8” rule. Water needs vary widely based on your size,
activity level, diet, climate, and health status.
Reviews from health sites like Healthline note that the original number may have
been misinterpreted: total fluid needs include water from food and other drinks,
not just plain water.

Recent coverage of hydration guidelines emphasizes listening to your body (thirst,
urine color, energy levels) rather than obsessively counting glasses.
You might need more than eight glassesor less. The real rule: don’t ignore your
thirst, and don’t treat water like a punishment or a personality trait.

9. “Swallowed Gum Stays in Your Stomach for Seven Years”

Why people believe it

This myth thrives on mild fear and parental convenience. “Don’t swallow your gum,
it’ll stay in your stomach for seven years!” is a quick way to make kids spit it
into the trash instead of swallowing or sticking it under the table.

What science actually shows

Gastroenterologists and pediatric specialists are very clear: while chewing gum
base isn’t easily digested, it doesn’t just camp out in your stomach for years.
It typically passes through the digestive system and comes out the other end in
a few days, like other indigestible material.

Medical centers and health explainer sites repeatedly debunk the “seven-year”
claim as folklore.
Swallowing a piece now and then is usually harmless, though swallowing large
amounts frequentlyespecially in kidscould, in rare cases, contribute to a
blockage.

So yes, spit your gum out in the trash for politeness and plumbing reasons. But
your stomach is not secretly a gum storage unit.

10. “The Seasons Are Caused by How Close Earth Is to the Sun”

Why people believe it

It feels logical: far from the Sun = cold, closer to the Sun = hot. Many people
assume Earth’s slightly elliptical orbit explains why we have summer and winter.

What science actually shows

Space agencies and science education programs emphasize that Earth’s seasons are
driven mainly by axial tiltabout 23.5 degreesnot by small changes in distance
from the Sun.
Interestingly, Earth is actually farthest from the Sun during Northern
Hemisphere summer, and closest during winter.

Because of the tilt, different hemispheres receive more direct sunlight at
different times of the year. That changes how concentrated the Sun’s energy is
on the surface, which matters far more than the relatively tiny variation in
Earth–Sun distance.

In short, summer isn’t about being closer to the Sunit’s about being tilted the
right way. Think “angle,” not “distance.”

What These Myths Teach Us

These ten myths stick around because they’re simple, memorable, and often
emotionally satisfying. “Sugar makes kids hyper” gives parents something tangible
to blame. “We only use 10% of our brains” flatters us with the idea of hidden
potential. “Vaccines cause autism” offers a clear villain in the face of a
complicated condition.

But reality is usually messierand more interesting. Modern research tools, from
brain scanners to satellite cameras, allow scientists to test old beliefs in
ways we couldn’t before. The result is a growing pile of evidence that many
“everybody knows” facts are… well, not facts at all.

The takeaway isn’t that we should feel embarrassed for believing these myths; it’s
that we should stay curious. Question the things that sound too neat, too tidy,
or too repeated. Check where the claim came from. Ask whether experts in the
relevant field actually agreeor if this “fact” is just an overconfident meme
from 1978 that never retired.

Experiences and Stories Around Commonly Believed Myths

If you want to see how powerful these myths are, just drop one of them into a
conversation and watch what happens. Tell a group of friends, “You know we don’t
actually only use 10% of our brains,” and chances are at least one person will
push back: “Wait, really? I heard that in school.” For years, people have built
entire motivational talks around that idea. It feels inspiring, so it sticks.

Think about family gatherings. Many people grew up with a relative who banned
knuckle cracking at the dinner table, swearing it would “ruin your hands” by the
time you were 30. Some kids responded by stopping. Others turned it into a secret
habit, cracking away under the table or in their rooms. Even after reading about
studies that found no link to arthritis, plenty of adults still feel a tiny stab
of guilt when they pop a knuckle. That’s how deeply early warnings can lodge in
your brain.

The vaccine–autism myth plays out on an even more emotional level. In parenting
groups, someone might share a story about their child’s autism diagnosis happening
not long after a round of shots. The timing feels suspicious, and the human mind
is wired to look for patterns and causes. Others, hearing those stories, feel the
fear first and see the data secondif at all. In many online discussions, people
who try to share large-scale studies and expert reviews find themselves up against
heartfelt anecdotes and viral posts that are much easier to relate to than a
200-page research paper.

Hydration myths show up in everyday routines. Many people now carry giant water
bottles marked with motivational timestamps: “9 AM – Keep going!”, “3 PM – Almost
there!” For some, this is a fun accountability trick. For others, it becomes a
kind of quiet stressif they haven’t hit eight glasses by mid-afternoon, they
worry they’re already messing up their health. Then, when they learn that fluid
needs are individual and that food, coffee, and other drinks count, you can almost
see the relief wash over them. The experience becomes a reminder that even
“healthy habits” can be built on shaky assumptions.

The gum myth tends to show up in childhood memories. Many adults can recall
sitting in school, suddenly realizing they’d swallowed their gum and feeling
a small wave of panic: “That’s it, it’s in there for seven years.” Some kids
even tried to calculate when their “gum sentence” would officially end. Later,
hearing a doctor casually explain that the digestive system moves gum along like
other indigestible material can feel almost anticlimacticbut also freeing. It
transforms a secret fear into a slightly ridiculous story to tell later.

Travel and astronomy fans often run into the Great Wall myth. Someone visiting
China might proudly post on social media that they’ve seen “the only man-made
object visible from space.” When an astronaut or science communicator replies
with a gentle correction, the reactions vary: some people appreciate the update,
while others dig in and argue. How people respond becomes a little experiment in
intellectual humility. Are we willing to give up a cool fact if reality is less
dramatic but more accurate?

Classroom experiences around seasons can be equally telling. When teachers ask
students why it’s summer, a lot of them say, “Because Earth is closer to the
Sun.” When those same students see diagrams showing Earth’s tilt or learn that
their hemisphere is actually farther from the Sun in summer, a lightbulb goes on.
The moment is small but powerful: it shows that something that “felt” correct
wasn’t, and that checking your assumptions is part of learning.

Animal-related myths also shape how people behave. If someone thinks bats are
blind and clumsy, they may see them as creepy or dangerous. Once they learn that
bats have functional eyes, impressive navigation skills, and important roles in
ecosystems (like eating huge numbers of insects), that fear can shift into
curiosity or even respect. Similarly, realizing that goldfish are capable of
learning and remembering for long stretches can change the way people care for
them, moving from “disposable pet” to “living creature with real needs.”

Altogether, everyday experiences with these myths point to a bigger pattern: we
don’t just inherit stories; we live inside them. They shape what we worry about,
how we parent, what we post online, and how we talk to each other. The good news
is that updating our mental “fact files” can be surprisingly satisfying. When you
replace an old myth with a clearer understanding, you don’t just gain a new piece
of triviayou practice being the kind of person who can change their mind when
the evidence changes. And that might be the most important “life hack” of all.