Growing up, we often accept certain “facts” without question. However, many of these truths we learned in our youth are misconceptions debunked by science. Let’s explore some widespread beliefs from our childhood that have since been proven false, shedding light on what science actually says.
Keep track of how many you already knew to be lies, and let us know at the end!
1. Humans use only 10% of their brains
The myth that humans use only 10% of their brains has been debunked by science. Neuroimaging studies show that all brain parts have specific functions and are active at different times. While not all areas are engaged simultaneously, every region is utilized, disproving the notion that 90% of the brain is dormant. This highlights that the brain, although complex, is fully employed in various activities throughout our lives.
2. The Great Wall of China is visible from the moon
The belief that the Great Wall of China can be seen from the moon is untrue. Astronauts confirm that the Great Wall is not visible from the moon with the naked eye. In fact, even Earth-orbiting astronauts need visual aids to see it. This myth likely arose due to the Wall’s historical significance and immense scale, leading to exaggerated claims about its visibility from space.
3. It takes seven years to digest chewing gum
The myth that chewing gum takes seven years to digest is not supported by science. Chewing gum is largely indigestible but doesn’t stay in the stomach. Instead, it passes through the digestive system at the same pace as other matter. While the gum’s base cannot be digested, it is expelled by the body typically within a day or two, just like any other food that can’t be digested.
4. Sugar causes hyperactivity in children
The belief that sugar causes hyperactivity in children is a common myth. Scientific studies have thoroughly examined this claim and found no evidence to support it. Research involving controlled testing has shown that sugar does not affect children’s behavior or cognitive abilities. The idea likely persists due to observational biases and anecdotal reports, but the consensus in the scientific community is clear: sugar does not cause hyperactivity in children.
5. Shaving hair makes it grow back thicker
The myth that shaving hair makes it grow thicker is widely believed but scientifically debunked. Shaving cuts the hair close to the skin, causing the new growth to appear thicker and more noticeable because it is blunt and not tapered. However, shaving does not change hair follicles’ number, texture, or growth rate. Thus, the regrown hair seems thicker but is the same as before.
6. We swallow eight spiders a year in our sleep
The myth that people swallow eight spiders a year in their sleep is widely circulated but entirely false. In reality, spiders generally avoid humans, and the idea of them crawling into mouths while people sleep lacks scientific backing. This urban legend likely persists due to its shock value and the common fear of spiders, but rest assured, it’s not supported by any scientific evidence.
7. Cracking knuckles leads to arthritis
The belief that cracking knuckles causes arthritis is a widespread myth. Scientific research has shown that there is no direct link between knuckle cracking and the development of arthritis. The popping sound heard when cracking knuckles results from gas bubbles bursting in the synovial fluid, not from damaged bones or joints. Studies indicate that knuckle cracking does not harm the joints or lead to arthritis.
8. Lightning never strikes the same place twice
The myth that lightning never strikes the same place twice is false. Lightning can strike any location multiple times, especially if it’s a tall, pointed, or isolated object. Buildings like the Empire State Building may be struck often during a single thunderstorm. Scientific observations have shown that certain areas are more prone to repeated lightning strikes due to their geographical features and weather patterns, debunking the old saying.
9. Dogs sweat by salivating
The common belief that dogs sweat by salivating is incorrect. In reality, dogs primarily regulate their body temperature through panting, which helps evaporate heat away from their body. Additionally, dogs have sweat glands located in their paw pads, which also aid in cooling, albeit to a lesser extent. Salivating does not significantly contribute to a dog’s ability to cool down; instead, it helps them digest food and keep their mouth moist.
10. Reading in dim light ruins your eyesight
Reading in dim light is often believed to permanently damage eyesight, but this is a myth. While reading with insufficient lighting can cause temporary eye strain or discomfort, it does not cause lasting harm to the eyes. Scientific studies confirm that any symptoms experienced while reading in poor lighting are temporary and do not lead to long-term deterioration of vision. It’s more about comfort and preventing temporary fatigue than protecting against permanent damage.
11. Bats are blind
The myth that bats are blind is incorrect. In fact, bats have vision and can see, although many species rely more heavily on echolocation to navigate and find food in the dark. Echolocation involves emitting sound waves and interpreting the echoes that bounce back from objects, allowing bats to have precise spatial awareness even in complete darkness. Therefore, while their eyesight might not be their primary sense, bats are certainly not blind.
12. Water conducts electricity
It’s a common belief that water conducts electricity, but pure water is a poor conductor. The conductivity seen in typical water sources comes from minerals and impurities that dissolve in it. These substances release ions, which are what actually carry the electrical current. Therefore, it’s the minerals, not the water itself, that facilitate electrical conductivity. This explains why distilled water lacks these impurities and does not conduct electricity well.
13. Eating turkey makes you sleepy because of tryptophan
The common belief that eating turkey makes you sleepy due to its tryptophan content is a myth. While turkey does contain tryptophan, an amino acid linked to sleep, the amount isn’t sufficient to induce sleepiness. The fatigue often felt after eating a Thanksgiving meal is more likely caused by consuming large quantities of food and carbohydrates, which can increase serotonin levels in the brain, promoting a sense of tiredness and relaxation.
14. Humans have five senses
The belief that humans have only five senses—sight, hearing, taste, touch, and smell—is a common misconception. Humans possess additional senses such as balance, temperature perception, and pain, among others. This expanded sensory understanding comes from scientific studies that identify various receptors and nerve pathways responsible for detecting changes in our internal and external environments, demonstrating our ability to perceive the world in more complex ways than just the traditional five senses.
15. Goldfish have a three-second memory
The myth that goldfish only have a three-second memory is false. Research shows that goldfish can remember things for months. They can learn and remember various tasks, such as navigating mazes or recognizing individuals. This demonstrates that their memory capacities are much more sophisticated than the myth suggests, debunking the long-held belief that goldfish have extremely short memory spans.
16. Alcohol keeps you warm
The belief that alcohol warms the body is a myth. Although drinking alcohol can cause blood vessels to dilate, creating a temporary sensation of warmth, it actually leads to a decrease in core body temperature. This happens because the expanded blood vessels increase heat loss from the body’s surface. Consequently, rather than keeping you warm, alcohol can make you more susceptible to cold temperatures.
17. If you touch a baby bird, its mother will reject it
The myth that touching a baby bird will cause its mother to reject it is scientifically disproven. Birds have a limited sense of smell, so they cannot detect human scent on their chicks. Instead, most birds are very committed to their offspring and will not abandon them easily. This myth likely originated as a well-meaning attempt to prevent people from disturbing wildlife unnecessarily.
18. Eating at night makes you gain weight more than eating during the day
The myth that eating at night leads to more weight gain than eating during the day has been debunked by science. Research shows that weight gain is primarily determined by the total amount of calories consumed versus the amount expended, regardless of the timing of meals. Therefore, it’s the overall calorie balance, not the time of day of eating, that affects weight gain. Managing total caloric intake is key to maintaining a healthy weight.
19. Ostriches bury their heads in the sand when scared
The myth that ostriches bury their heads in the sand when frightened is not true. Ostriches do not hide their heads to avoid danger. Instead, they might lay their heads on the ground when trying to blend in with the environment, giving the appearance of “burying” their heads. In reality, ostriches are likely to flee or use their strong legs to defend themselves when threatened, rather than trying to hide in such a peculiar way.
20. Different parts of the tongue detect different tastes
The myth that different regions of the tongue are responsible for specific tastes—sweet, sour, salty, and bitter—has been debunked by science. Research shows that all parts of the tongue can detect these tastes. The misconception likely originated from an incorrect interpretation of an early 20th-century study. Modern studies, using more accurate methods, have proven that taste receptors for all flavors are distributed throughout the tongue, not confined to specific areas.
21. Cell phones cause cancer
Scientists have thoroughly investigated the myth that cell phones cause cancer. Extensive research, including studies by health organizations worldwide, has found no conclusive evidence linking cell phone use with an increased risk of cancer. The radiofrequency energy emitted by cell phones is non-ionizing and not strong enough to damage DNA or cells in a way that would initiate cancerous growth. Thus, current evidence does not support this myth.
22. Hair and fingernails continue to grow after death
The belief that hair and fingernails continue to grow after death is a myth. In reality, what happens is that the skin around hair and nails dries out and shrinks after death. This shrinkage can make hair and nails appear longer, although they are not actually growing. Scientifically, growth processes cease once the body no longer has the physiological capabilities to support them, which stops after death.
23. Adding salt to water makes it boil faster
The myth that adding salt to water speeds up boiling is false. Science shows that salt actually raises the boiling point of water, meaning it requires more heat and thus more time to reach a boil. While the effect of salt on the boiling point is minimal, it does not make water boil faster. Instead, the added salt primarily enhances flavor, making it a common practice in cooking despite its minimal impact on boiling time.
24. Vitamin C can prevent colds
The belief that vitamin C can prevent colds is a widely held misconception. Despite its importance for overall health, extensive research has shown that vitamin C does not prevent the common cold. Although it may slightly reduce the duration of cold symptoms in some people, its effectiveness in outright prevention is not supported by scientific evidence. Therefore, while beneficial for other health aspects, vitamin C is not a reliable preventive measure against colds.
25. You need to drink eight glasses of water a day
The idea that everyone must drink eight glasses of water daily is a common myth without scientific backing. Water needs vary by individual, influenced by factors like activity level, environment, and overall health. It’s important to stay hydrated, but the amount of water each person needs can differ significantly from the eight-glasses rule. Listening to your body’s natural thirst cues is a more effective guideline for maintaining hydration.
How did you do?
How many did you already know to be NOT true? Or what were you most surprised about? Let us know in the comments.
