That’s not true!

15 myths about the human body you should stop believing

Image: The New York Public Library

Think you know your body? Think again. Many "facts" we hear about the human body are actually just popular myths that have been long debunked by science. From the color of your blood to the capacity of your brain, join us as we separate truth from fiction.

Image: David Matos

Myth: We only use 10% of our brains.

Truth: Brain scans show that most areas of the brain are active even during simple tasks. Modern advanced imaging reveals that nearly all parts of the brain have specific roles. This is why damage to any area can lead to severe impairments. Come on, this one was fairly obvious, evolution wouldn’t keep an organ with 90% redundancy.

Image: Tekara

Myth: Swallowed gum stays in your stomach for seven years.

Truth: Gum passes through your digestive system just like any other non-digestible materials. This means that, while it’s true that it cannot be broken down, it will simply exit your body within a few days, along with waste. There’s really no evidence of gum lingering in your stomach for years after swallowing.

Image: Eddie Jones

Myth: Cracking knuckles causes arthritis.

Truth: Studies show no link between knuckle cracking and arthritis. The sound it makes might make you cringe a bit, but it actually comes from minuscule gas bubbles collapsing in joint fluid, not bone damage. In fact, knuckle cracking indicates normal joint function. Arthritis is caused by other factors like age, genetics, and injuries.

Image: Supply

Myth: Shaving makes hair grow back thicker.

Truth: Who hasn’t heard this one? A very popular myth, it has long been debunked. The truth is that shaving can make hair appear thicker because unshaven hair ends in fine points, while shaving cuts it at the surface, leaving a blunt edge that feels coarser. However, hair regrowth is determined solely by genetics and hormones, not by how it’s trimmed.

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Myth: Blood is blue in your veins and red when exposed to air.

Truth: Blood is always red, though it can appear blue under the skin due to an optical effect caused by light diffraction. However, the oxygen level in blood can actually affect its hue, that goes from a bright red (oxygen-rich) to a darker red (oxygen-poor).

Image: Myriam Zilles

Myth: Sugar makes kids hyperactive.

Truth: Research consistently shows no direct link between sugar consumption and hyperactivity. If you are a parent, you might be convinced otherwise, but data suggests that this is often a case of self-fulfilling prophecy. Parents' expectations (as well as children’s awareness of the myth) can influence perceived—or very real—behavior changes, but sugar itself is not the culprit here.

Image: Cole Patrick

Myth: You lose most body heat through your head.

Truth: Mothers may cringe at this, but no, the head is not the heat sink many believe it to be. Heat loss simply depends on the exposed area. If your head is uncovered while the rest of your body is insulated, it might feel like most heat escapes from your head—but it’s not necessarily the primary heat-loss site.

Image: Eeshan Garg

Myth: Drinking alcohol kills brain cells.

Truth: Alcohol is far from being good for you, but it doesn’t literally kill brain cells as many believe. Instead, it can impair the communication between them. Among other things, long-term excessive drinking can damage dendrites, leading to cognitive and behavioral changes, but the cells themselves remain intact. Moreover, with a healthy lifestyle and given enough time, the brain can actually repair itself to some extent.

Image: Sean Benesh

Myth: Different parts of your tongue taste specific flavors.

Truth: Ever seen a taste map showing specific areas of the tongue associated with certain flavors? Well, forget it. It turns out that taste receptors for sweet, salty, sour, and bitter are actually distributed evenly across the tongue. The "tongue map" was a misinterpretation of early research.

Image: Klim Sergeev

Myth: Reading in dim light damages your eyes.

Truth: Another parental favorite. While dim lighting can temporarily strain your eyes, it doesn’t cause any permanent damage. Your eyes adapt to low light but may need time to adjust back.

Image: Clay Banks

Myth: Sweating removes toxins.

Truth: Sweat is mostly water and salts, not toxins. The liver and kidneys handle detoxification, while sweat’s primary role is regulating body temperature.

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Myth: Hair and nails keep growing after death.

Truth: After death, the skin dehydrates and retracts, giving the appearance of growth. Hair and nail cells require living tissue to grow, which ceases after death.

Image: Harry Quan

Myth: Humans only have five senses.

Truth: In addition to sight, smell, touch, taste, and hearing, we have other important senses like balance (vestibular), temperature (thermoception), and body position (proprioception). Some scientists count up to 33 senses in total! Bet this one caught you off guard.

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Myth: Sweating leads to fat loss.

Truth: Just like the "sweat = toxins" myth, this is simply not true. Sweat loss reflects water weight, not fat loss. While you might weigh slightly less after intense exercise, you’ll regain that weight after rehydrating. Fat is burned through metabolic processes, not perspiration.

Image: Tamara Bellis

Myth: The phases of the moon influence hair growth.

Truth: There is no scientific evidence linking moon phases to hair growth. This myth likely originated from agricultural practices that encourage planting seeds according to the moon's phases (also not scientifically proven). Studies show that hair growth is primarily determined by genetics, nutrition, and overall health, not lunar cycles. As long as you are healthy, hair grows at a consistent rate, regardless of the moon's phase.

From fact to fiction

Don't do this! 10 popular myths busted by science

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Some claim that humans only use 10% of our brains, others say that eating turkey makes you sleepy, and everyone has heard the supposed remedy for a jellyfish sting. Like these, there are many well-known myths we frequently repeat without giving them much thought. Fortunately, science has taken the time to put these ideas to the test to see if they are true: it turned out that they were not! Join us to discover these 10 popular myths that science has debunked.

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For centuries, both children's tales and cartoons have depicted the idea that cheese and mice are inseparable. However, science has revealed that mice don’t have a particular preference for cheese over other types of food. Although this is a common stereotype, mice are more drawn to foods high in sugar, such as candy or fruit.

Now you know—next time you’re setting a mouse trap, you might want to bait it with a Snickers bar instead of a piece of cheese.

Image: Claudio Schwarz

There is a famous myth going around that claims eating turkey can make you sleepy. However, this is not exactly the case. The myth arises because turkey contains tryptophan, an amino acid that helps the body produce serotonin and melatonin, essential for promoting sleep. However, the amount of tryptophan in turkey is not enough to make you drowsy. So, you can enjoy your turkey dinner without worrying about nodding off at the table!

Image: Bernd Dittrich

For years, it was widely believed that the Great Wall of China was the only human-made structure that could be seen from outer space with the naked eye. However, while we would all like it to be true, this claim is actually a myth.

It's a fact that the Great Wall is indeed very long, but it's also relatively narrow. That means that as we gain altitude, the Great Wall blends in with the surrounding natural landscape.

Image: Felix Mittermeier

A common myth claims that lightning never strikes the same place twice. This may be reassuring to many, but science—and nature itself—have proven otherwise. In fact, lightning can strike the same location multiple times, particularly if it’s a tall structure or an area containing water or metal.

The safest and most recommended thing to do during a lightning storm is to stay indoors.

Image: sanjiv nayak

Goldfish are said to have a memory span of only a few seconds. This myth probably originated due to the repetitive behaviors observed in these fish. However, science has debunked this notion.

Through various experiments and research, it has been demonstrated that goldfish can remember multiple things for several weeks. For example, they can recognize the faces of their keepers, remember feeding schedules, and even associate certain stimuli with rewards.

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You're chilling, enjoying some chips, when suddenly—oops! One hits the floor. What do you do in that case? Do you follow the so-called "five-second rule"? According to this myth, if you drop food on the floor, it's safe to eat it if you pick it up within 5 seconds.

While we would like it to be right, science discourages this idea. The truth is, as soon as food hits the floor, any bacteria present can transfer to it instantly.

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A classic cartoon scene: the frightened ostrich burying its head in the ground. You've probably seen it, too, right? Although this is a common belief, ostriches never actually bury their heads.

This myth likely stems from the way ostriches care for their nests. These birds make a small hole in the ground and place their nests there to keep them safe. From a distance, when we see the ostrich sticking its head in the ground, it is actually taking care of its chicks!

Image: Giovanni Calia

This is one of the most widespread myths in the world, originating from bullfighting traditions. The myth claims that the color red makes bulls extremely angry, driving them into a mad rage. However, this isn’t true.

In reality, bulls can’t even perceive red—or many other colors—the same way humans do. Experts believe bulls react to the movement of the bullfighter’s cape, not its color.

Image: Jeffrey Hamilton

What should you do if you get stung by a jellyfish? Many of us instantly think of the myth that urinating on the sting will relieve the pain. Unfortunately, not only is this a myth, but it can actually make things worse!

If you're unlucky enough to be stung by a jellyfish, the best course of action is to rinse the affected area with vinegar to neutralize the venom. Be sure to avoid touching the sting with your bare hands to prevent further irritation or spreading the venom.

Image: Chewy

As kids, many of us grew up hearing that dogs only see in black and white. Luckily for our pets, that's just a myth!

Dogs perceive colors in a way that's different from ours. While the human eye has three types of color receptors, dogs have only two. In other words, while we can see a broad spectrum of colors, dogs see a more limited range, similar to someone with red-green color blindness.