28 Incorrect 'Facts' You May Have Learned In School—part 2 of 2

Last week I shared 14 of the 28 Incorrect Facts with you in part 1 of my 2-part blog. This week I'm sharing the other 14. Like many myths, these stories often have a kernel of truth to them. It just isn't what you learned in school.

MYTH: Bats are blind

If this were true, would Bruce Wayne really model his superhero identity of Batman after an animal that can't see? You've probably heard someone use the phrase blind as a bat to describe someone. Contrary to this widespread belief, bats are not blind. Large bats are said to see three times better than humans. In addition to a normal sense of sight, bats rely on a technique at night known as echolocation. In low-light environments, as the term echolocation suggests, they are able to locate the source of sounds based on echoes that are produced. This is particularly helpful when trying to find prey and other food sources.

MYTH: Tilting your head back will stop a nosebleed

As a child, you might have been taught to tilt your head back in order to stop a nosebleed. Doctors agree this is not the solution. In the case of a nosebleed, you should tilt your head forward and pinch right below the bridge of your nose to stop the flow of blood rushing out of your nostrils. Tilting your head back might actually lead to more damage. It can cause blood to enter your throat which leads to your stomach and further unpleasant complications.

MYTH: When you swallow gum, it stays in your body for seven years

Gum will stay in your body for some time, but nowhere near seven years. Unlike most food, gum can't be broken down by the body's enzymes and acids. Therefore, that piece of gum goes straight through your system without being dissolved or broken into smaller pieces, and is later expelled. Even though swallowing a wad of gum accidentally or on purpose won't cause it to stay with you for a long period of time, it's probably best to just spit it out when you're finished. There have been rare cases of children having internal issues due to swallowed gum.

MYTH: Camels store water in their humps

You might have been taught that the purpose of a camel's hump is to store water, but this is not true. Some camels have one hump while others have two, but regardless of quantity, they serve the same purpose—to store fat. The stored fat serves as a substitute for food when camels are traveling long distances with limited available resources. According to Animal Planet, a camel can use the fat as an energy source to replace approximately three weeks of food. It's the camel's red blood cells that account for its ability to last one week without water. Unlike other creatures, a camel has oval-shaped blood cells that are more flexible and enable them to store large portions of water.

MYTH: You must drink eight glasses of water a day

The origin of this myth isn't entirely clear, but it is believed that people were convinced of this health rule after the Food and Drug Administration suggested it as a guideline in a 1945 published paper. The truth is that you don't need to drink eight glasses of water each day. Your body will still receive necessary hydration from other fluids and foods. It's probably best to drink a healthy amount of water and indulge in a moderate amount of less healthy beverages (like sugary ones). The most important thing is remembering that your body needs to maintain a balance since fluids are constantly entering and leaving the body. The amount of hydration needed also varies from person to person, since there are factors like age, health conditions, and activity level to consider.

MYTH: There's a five-second rule that applies to food that falls on the floor

If you've ever dropped a piece of food on the floor and quickly picked it up within five seconds, deeming it safe to eat, you have been misguided by a popular health myth. According to the five-second rule, food that falls on the floor is acceptable to consume as long as it hasn't stayed on the unclean surface for more than five seconds. Research has found that the rule is not accurate or applicable. While it's true that the longer dropped food stays on a surface the more germs it attracts, but food will instantly become contaminated as soon as it hits the floor.

MYTH: An apple a day keeps the doctor away

While the nursery rhyme has the laudable goal of getting kids to eat more fruit, it doesn't really work. Apples have vitamin C and fiber, but they are far from containing all the nutrients people need to stay healthy. The best diet you could have is one that consistently gives you a well-rounded group of nutrients. One that uses a lot of vegetables, whole grains, and healthy fats is probably ideal.

MYTH: You can catch a cold just by being cold

It makes some kind of intuitive and linguistic sense—if you're cold and uncomfortable, your health will suffer and you'll catch a cold. But that's not quite how it works. In reality, viruses that cause people to catch colds predominate in North America during the winter. Furthermore, people tend to stay indoors when it's cold and in close quarters, enabling viruses to spread more easily. Low indoor humidity, which happens when the heater is on, is also conducive to the flu. So it isn't so much the cold causing colds. It's the cold weather creating conditions where colds spread.

MYTH: You'll get cancer if you stand too close to the microwave

You might have been taught as a child that you shouldn't stand in front of the microwave because of potential effects on your health. This is mainly due to concerns over radiation exposure. Radiation exists on a spectrum, and the radio frequency radiation used by the kitchen appliance is low-energy which is not harmful. According to the American Cancer Society, the energy emitted by microwave ovens is contained within the device and if used correctly "there is no evidence that they pose a health risk to people."

MYTH: If you shave your facial hair, it'll grow back thicker

A biologist who has studied hair for more than 30 years said that has not proven to be true. A razor cleanly cuts the hair, which results in blunt ends. Once the hair grows back, it might feel thicker because of the bluntness.

MYTH: If you eat plenty of carrots, you'll have great eyesight

The exact origin of this myth isn't clear, but it's believed that it became a widespread idea during World War II. When the British issued citywide blackouts in their attempt to defeat the German air forces, one UK soldier, John Cunningham successfully shot down planes. From there, the country started spreading posters and other propaganda that credited carrots as the reason for his exceptional night vision. This was believed to be a myth spread by the government to hide the knowledge of radar from the Germans. The bottom line is that although carrots are high in Vitamin A, you won't have magically superior eyesight or night vision.

MYTH: Sharks can smell a drop of blood from miles away

Sharks are known for having an acute sense of smell. Although they have a better sense of smell than many other creatures, they cannot detect a single drop of blood that's miles away. These predators can pick up on small amounts of different chemicals in the water, but there are other factors that should be taken into consideration (like what kind of substance and the speed of the water current). Some shark species can detect a drop in an Olympic-sized swimming pool while others can sense chemicals up to a few hundred meters away.

MYTH: Milk is good for you

Yes, that's right. The proven health benefits of milk are few and far between. It's mostly the product of an enormously successful advertising campaign. But humans are the only mammals to consume milk during adulthood. And while no one disputes that milk contains essential nutrients to help children's bodies grow, study after study shows there's no evidence milk does much good for older children or adults.

MYTH: Coffee stunts children's growth

It's a myth grown-ups use to stop kids from drinking coffee—it will stunt your growth and make you shorter later in life. The idea behind it is that caffeine limits the body's ability to absorb calcium, which is important for the growth of younger children in particular. But the overall idea that caffeine is going to significantly stunt growth is bunk.