SmartAss FactsMyths Debunked
Popular beliefs examined with primary sources — and found to be completely false.
Some of the most confidently repeated "facts" are myths. The brain myth, the goldfish memory myth, the lightning myth — each has been circulating for decades despite being directly contradicted by peer-reviewed research. Every entry here includes the actual science and the exact origin of the wrong belief.
You Only Use 10% of Your Brain
False. You use virtually all of your brain, continuously. Brain imaging studies using fMRI and PET scans show all regions are active during normal daily tasks.
Read the full debunk →Goldfish Have 3-Second Memories
False. Goldfish can retain memories for months, not seconds. Controlled studies at Plymouth University trained goldfish to navigate mazes and remember results for months.
Read the full debunk →The Great Wall of China Is Visible from Space
False. The Great Wall cannot be seen by the naked eye from low Earth orbit. At its widest, the wall is only about 9 metres — far too narrow to resolve without optical aid.
Read the full debunk →Cracking Your Knuckles Causes Arthritis
False. No scientific study has found a causal link between knuckle cracking and arthritis. The most famous self-experiment — 60 years, one hand only — found no difference.
Read the full debunk →Lightning Never Strikes the Same Place Twice
False. Lightning routinely strikes the same location many times. The Empire State Building is struck by lightning around 20–25 times per year.
Read the full debunk →Reading in Dim Light Ruins Your Eyesight
False. Reading in dim light causes temporary eye strain and fatigue, but no clinical evidence shows it causes any lasting damage to vision.
Read the full debunk →Napoleon Bonaparte Was Unusually Short
False. Napoleon was approximately 5 feet 7 inches tall (170 cm), which was average for a French man of his era. The confusion arose from a mix-up between French and English inches.
Read the full debunk →Humans Swallow 8 Spiders Per Year in Their Sleep
False. There is no scientific evidence that humans routinely swallow spiders in their sleep. The vibrations, heat, and CO₂ from sleeping humans actively repel spiders.
Read the full debunk →Bulls Are Enraged by the Color Red
False. Cattle are red-green colorblind and cannot distinguish red from green. Bulls in bullfighting react to the movement of the cape, not its colour.
Read the full debunk →Humans Have Only Five Senses
False. Humans have far more than five senses. Depending on how strictly you define a "sense," modern neuroscience counts between 9 and 21 — including proprioception, thermoception, and vestibular sense.
Read the full debunk →Sugar Makes Kids Hyperactive
False. More than a dozen double-blind, placebo-controlled trials have found no link between sugar consumption and hyperactivity in children. The effect appears to be entirely in the parents' expectations.
Read the full debunk →You Lose Most Body Heat Through Your Head
False. Heat loss is proportional to the surface area of skin exposed. The human head represents roughly 10% of total body surface — no more heat escapes through it than any other uncovered area.
Read the full debunk →Bats Are Blind
False. All known bat species have functional eyes and can see. Many have good low-light vision. Microbats use echolocation to navigate in darkness, but that does not mean they are blind.
Read the full debunk →Einstein Failed Math in School
False. Einstein did not fail mathematics. He mastered calculus before the age of 15 and consistently excelled in maths and physics. The myth stems from a misreading of the Swiss grading system.
Read the full debunk →Shaving Makes Hair Grow Back Thicker and Darker
False. Shaving has no effect on hair thickness, colour, or growth rate. This has been confirmed by multiple controlled studies. The blunt cut just makes regrown hair feel stubbly.
Read the full debunk →Swallowed Chewing Gum Stays in Your Stomach for 7 Years
False. Swallowed gum does not remain in the stomach for 7 years. While the gum base is indigestible, it moves through the digestive system normally and is excreted within days.
Read the full debunk →Blood in Your Veins Is Blue
False. Human blood is always red. Oxygenated arterial blood is bright red; deoxygenated venous blood is a darker red. Veins appear blue through skin because of how skin tissue absorbs light.
Read the full debunk →Alcohol Warms You Up in Cold Weather
False, and dangerously so. Alcohol causes vasodilation — widening of blood vessels near the skin — which produces a sensation of warmth but actually accelerates core body heat loss.
Read the full debunk →Dogs Are Completely Colourblind
Misleading. Dogs are not completely colourblind — they have dichromatic colour vision and can distinguish blue from yellow. They simply cannot distinguish red from green.
Read the full debunk →A Penny Dropped from a Skyscraper Can Kill Someone
False. A penny dropped from a skyscraper cannot kill anyone. Due to its flat, tumbling shape, a penny reaches a terminal velocity of only about 40–50 km/h — painful, not lethal.
Read the full debunk →People Are Either Left-Brained or Right-Brained
False. Brain imaging of over 1,000 people found no evidence that individuals preferentially use one hemisphere. Both hemispheres work together for almost every cognitive function.
Read the full debunk →You Must Drink 8 Glasses of Water a Day
False. The "8 glasses a day" rule has no scientific basis. Daily fluid requirements vary significantly by body size, climate, activity level, and diet. Much hydration comes from food.
Read the full debunk →Hair and Nails Continue to Grow After Death
False. Hair and nails do not grow after death. Growth requires active cellular metabolism. What happens is the skin dehydrates and retracts, making hair and nails appear longer.
Read the full debunk →Cold Weather Causes the Common Cold
False. The common cold is caused by viruses — primarily rhinoviruses — not by cold temperatures. You cannot catch a cold from being cold. Viruses spread through contact, not weather.
Read the full debunk →Touching a Baby Bird Makes Its Mother Reject It
False. Most bird species have a very limited sense of smell and cannot detect human scent on their young. Birds do not abandon chicks simply because a human has touched them.
Read the full debunk →Different Parts of the Tongue Taste Different Flavours
False. The "tongue map" showing sweet at the tip and bitter at the back is a misrepresentation. Taste buds capable of detecting all flavours are distributed across the entire tongue.
Read the full debunk →Carrots Improve Your Eyesight
Misleading. Carrots are rich in beta-carotene, which the body converts to vitamin A — essential for retinal function. But eating more carrots than needed does not improve sight beyond normal.
Read the full debunk →Ostriches Bury Their Heads in the Sand
False. Ostriches do not bury their heads in the sand. An ostrich that buried its head would suffocate. They do lower their heads to turn eggs in ground nests — this may have inspired the myth.
Read the full debunk →High-Dose Vitamin C Prevents the Common Cold
Misleading. For most people, taking high-dose vitamin C does not prevent colds. Large meta-analyses show it may reduce duration by about half a day in adults, not prevent infection.
Read the full debunk →We Experience Taste Only Through Our Tongue
False. Taste buds are not limited to the tongue — they also exist on the soft palate, epiglottis, upper oesophagus, and even the gut. Smell contributes up to 80% of what we perceive as taste.
Read the full debunk →Camels Store Water in Their Humps
False. Humps store fat, not water. Camels manage dehydration through specialised oval-shaped blood cells and the ability to tolerate losing 30% of their body water without harm.
Read the full debunk →Diamonds Are Made from Coal
False. Most diamonds formed 1–3 billion years ago deep in the mantle, long before coal-forming land plants even existed. They are made from carbon under extreme heat and pressure.
Read the full debunk →Humans Evolved from Chimpanzees
False. Humans and chimps share a common ancestor from approximately 6–7 million years ago. We are evolutionary cousins, not direct descendants of modern chimpanzees.
Read the full debunk →Seasons Are Caused by Earth's Distance from the Sun
False. Seasons result from Earth's 23.5° axial tilt — not distance. Earth is actually closest to the Sun in January, during Northern Hemisphere winter.
Read the full debunk →Eating Before Swimming Causes Dangerous Cramps
False. No scientific evidence supports this rule. The American Red Cross formally abandoned this advice. Exercise after a large meal may cause discomfort, not dangerous cramps.
Read the full debunk →Daddy Long-Legs Are the Most Venomous Spider
False on two counts. Harvestmen (the most common "daddy long-legs") are not spiders and have no venom glands at all. Cellar spiders have mild venom that poses no threat to humans.
Read the full debunk →Chameleons Change Colour to Blend In
Mostly false. Colour change in chameleons is primarily for temperature regulation and social signalling — communicating mood and dominance. Camouflage is a secondary benefit.
Read the full debunk →Antibiotics Can Treat Viral Infections
False. Antibiotics only work on bacteria. They have zero effect on viruses. Misuse and overuse of antibiotics is a leading driver of dangerous antibiotic-resistant bacteria.
Read the full debunk →Mount Everest Is the Tallest Mountain on Earth
It depends on the measure. Everest is highest above sea level (8,849 m). Mauna Kea is tallest base-to-summit. Chimborazo in Ecuador is furthest from Earth's centre due to the equatorial bulge.
Read the full debunk →Alcohol Kills Brain Cells
False as stated. Alcohol disrupts synaptic signalling but does not kill neurons at typical drinking doses. Long-term brain damage from chronic heavy drinking occurs mainly through thiamine deficiency.
Read the full debunk →Lightning Rods Attract Lightning
False. Lightning rods do not attract lightning — they intercept strikes that would occur regardless and safely conduct the energy to ground, protecting the building.
Read the full debunk →Humans Are the Only Animals That Use Tools
False. Chimpanzees, crows, sea otters, dolphins, elephants, and even some fish use tools. Several species also manufacture tools from raw materials — not just pick them up.
Read the full debunk →Vaccines Cause Autism
False. The 1998 Wakefield paper claiming this was retracted as fraudulent. Dozens of independent studies across millions of children have found no link between vaccines and autism.
Read the full debunk →The Tongue Is the Strongest Muscle in the Body
False. The masseter (jaw muscle) generates the most force. The heart does the most sustained work. The glutes move the most mass. The tongue holds no absolute strength record.
Read the full debunk →Waking a Sleepwalker Is Dangerous
False. Waking a sleepwalker causes brief confusion and disorientation, not serious harm. The real danger is leaving them asleep to walk into hazards.
Read the full debunk →Dogs' Mouths Are Cleaner Than Human Mouths
False as a comparison. Dogs' mouths contain a different bacterial community from humans, not a smaller one. They routinely contact faeces, decaying matter, and soil.
Read the full debunk →Searing Meat Seals In the Juices
False. Searing creates no moisture barrier — seared meat loses just as much moisture as unseared. Its real value is the Maillard reaction, which creates hundreds of complex flavour compounds.
Read the full debunk →Toilet Flushes Differently in the Southern Hemisphere
False. Flush direction is determined by the toilet's inlet jets, not the hemisphere. The Coriolis effect on a toilet bowl is approximately 10 million times too weak to influence the direction.
Read the full debunk →The Five-Second Rule Makes Dropped Food Safe
False. Bacteria transfer on contact, not after five seconds. A Rutgers University study found contamination in every single trial, including at under one second of contact.
Read the full debunk →Microwave Ovens Cook Food From the Inside Out
False. Microwaves penetrate 1–3 cm and heat the outer layers first; heat then conducts inward. This is why the outside of food is hot while the centre remains cold.
Read the full debunk →Fortune Cookies Are Chinese
False. Fortune cookies were invented by Japanese-Americans in California in the early 1900s. They are virtually unknown as a traditional food in China.
Read the full debunk →Common Questions
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