Scientific Concepts You're Taught in School Which are Actually Wrong

Science can be an extremely complicated thing, and our understanding of the world around us is always changing. Unfortunately, both of those things can result in children being taught things in school that are just flat out wrong.

Sometimes it’s done for the sake of simplicity. The actual science may be too complicated for young students to understand, so they are instead taught an oversimplified lie which can be built upon later. For example, at some point you were probably taught that atoms are the smallest thing in the universe, only to later learn that those atoms are made up of three different subatomic particles, some of which are also made up of even smaller particles.

Other times, the facts that are taught in schools are things that were once believed to be true but have since been refuted. Unfortunately, the corrections often don’t spread as far or wide. Wolf researcher L. David Mech and primatologist Frans de Waal both played large roles in popularizing the concept of an alpha male, but both have spent far more time working to debunk this notion, particularly as it relates to humans.

Though that particular example likely isn’t something taught in most schools, it still shows how difficult it can be to set the record straight once an idea has taken hold.

But regardless of the reason they’re being taught, here are five scientific concepts you were likely taught in school which are actually wrong.

Deoxygenated Blood is Blue

There’s a good chance that you are already aware this is incorrect, but it is a pervasive myth that is still taught to young students and believed by many teachers and other adults. According to what is generally taught in schools, blood becomes red when it interacts with oxygen which it carries to the rest of your body through your arteries. After the oxygen is delivered, the deoxygenated blood becomes blue as it passes through your veins.

They further explain that this is in fact the reason that your veins are blue, and if you were to accidentally cut a vein the blood only appears red because it mixes with the oxygen in the air. Of course, anyone who’s ever had blood drawn or donated blood can immediately tell you that this is wrong. Oxygenated blood is much brighter, but the blood flowing through your veins is still red, just a darker shade.

The red colour doesn’t come from the oxygen itself, it comes from the molecule hemoglobin to which oxygen binds. Hemoglobin gets its red colour from the compound heme, which contains iron. Blue blood does exist, just not in humans. Some crustaceans have hemocyanin in their blood instead of hemoglobin, a molecule that produces a blue colour because it uses copper rather than iron.

So if deoxygenated blood isn’t blue, why then are our veins blue? The answer is that they’re not, it’s just an optical illusion. Your veins are mostly colourless, and they only appear blue because of the red blood contained within them. That probably sounds confusing, but like we said it’s all an illusion.

In order for veins to be visible, light needs to reach and illuminate them. However, red light, with its longer wavelength, is able to penetrate deeper into the skin. The shorter blue wavelengths are more easily absorbed by the skin and blood, creating the illusion that veins are blue.

This also isn’t even the case for everyone. Depending on how dark a person’s skin is and what undertones it has, the veins may appear blue, green, or purple. But these colours are all just the byproduct of how the white light interacts with and is scattered by the pigments in our skin. It has nothing to do with the colour of the veins or the blood itself, since human blood is always red.

Eating Carrots Improves Eyesight

Your teachers probably told you that eating carrots could improve your eyesight, because they were rich in beta-carotene. Neither implication of that statement is technically incorrect, but both are oversimplifications.

The first oversimplification is that beta-carotene is beneficial to your eye health. It’s not the beta-carotene itself but rather vitamin A that is important for eye health. Carrots already contain vitamin A, but your body can also convert beta-carotene into vitamin A as needed. This makes carrots an excellent source of the vitamin that is extremely important for maintaining your vision.

But while it’s important for maintaining eye health, can vitamin A from foods like carrots actually improve your vision? Technically yes, but only in the same way that eating oranges can cure gum disease and improve the rate at which your wounds heal. Gum disease and decreased wound healing are both symptoms of scurvy, which can be combated with oranges (though in modern times you’re more likely to just be given a vitamin C supplement). For a person with a diet that already includes plenty of vitamin C, however, those symptoms would be indicative of some other condition which oranges wouldn’t help with.

Similarly, vitamin A deficiency can cause a lot of problems with vision. It can be as small as poor night vision or dry eyes, but if the deficiency remains untreated long enough it can result in blindness. Photoreceptors in the eye begin to deteriorate as a result of vitamin A deficiency, which causes many of the vision problems associated with it, but reintroducing vitamin A to a person’s diet can often reverse those effects. How much can be reversed depends on the severity of the damage and how long the person has been deficient, but if a person is suffering vision loss from malnutrition and vitamin deficiency then yes, eating carrots can improve their eyesight.

But again, for a person with a reasonably healthy diet, such a vitamin deficiency is unlikely to be an issue, barring any other underlying medical conditions that might affect vitamin absorption. As such and despite what you may have been taught in school, eating carrots will neither improve your vision nor prevent age related deterioration that may require you to wear glasses when you get older.

Of course, when this was first being taught in schools, it’s possible that there was a lot more truth to the statement than there is now. Vitamin deficiencies were much more common in the past, especially during the Great Depression, so this may have been much more practical information back then when fighting these deficiencies was a more pressing concern. It was likely never removed from the curriculum because carrots are a really healthy food anyway, so there wasn’t any actual harm in trying to convince kids to eat their vegetables.

Humans Have Five Senses

It all began with Aristotle’s De Anima (On the Soul), Book 2 written in 350 BC. In the book, he dedicated five chapters to the five human senses: sight, sound, taste, touch, and smell. Each of these senses was connected to a different sensory organ, the eyes, ears, mouth, nose, and skin. In De Anima Book 3, Aristotle doubled down by saying that humans could not have any more senses because every sense required its own sensory organ.

It was believed that the only way a person could have a sixth sense was if they possessed some sort of supernatural ability, like telepathy or the ability to talk to the dead. This assertion that there are only five senses is still taught today, but it is entirely incorrect. Well, not entirely since those five senses absolutely do exist, but modern science has determined we have many more than just five senses.

There isn’t a scientific consensus on the exact number of senses we have, as there is some potential overlap and it depends on how a person chooses to define a “sense”. But there are nine senses that it is universally agreed that humans possess, with some scientists putting the number as high as 33.

Just like Aristotle’s original five senses, the four additional ones that are agreed upon are also tied to sensory organs; it’s just that an organ can be responsible for more than one sense, despite Aristotle’s assertion this wasn’t possible. For example, there’s the vestibular system located within your inner ear. This system, comprised of two organs, was not even known about until the 1800s, over 2,000 years after Aristotle published his work. These organs are responsible for a person’s sense of balance.

Then there’s the skin, the organ responsible for the sense of touch. However, our skin actually has four different types of sensory cells, each of which responds to stimuli related to a different sense. The first sense the skin is responsible for is touch, one of the five everyone is already familiar with. However, the skin also has receptors for our senses of pain and temperature as well. The fourth type of receptor in the skin is used for our sense of proprioception.

Proprioception relies on stimuli from cells in the skin, muscles and joints, and it is the sense that allows you to perceive your body and movement in space, particularly in relation to objects around you. For example, this is the sense that allows you to climb a set of stairs you’ve never seen before without needing to stare at your feet or constantly tap them around to find the top of the next stair.

Those four senses, balance, pain, temperature, and proprioception, are widely agreed upon and are easily tied to sensory organs. There are other senses as well that are less agreed upon, such as your sense of time, seeing light and seeing colour being classified as two different senses, and interoception, or your body’s internal awareness. Interoception encompasses all stimuli passed from the body to the brain, such as your feelings of hunger, having a full bladder, or awareness of your current heart rate.

The Taste Map

Students have been learning about the taste map for decades, despite the fact that it has been heavily refuted. The premise is simple: the tongue is divided into specific sections, and each section handles one of the four basic tastes: bitter, sour, salty, and sweet. Depending on when you were presented with this diagram, however, you might have noticed a couple unusual things about the map.

First, all of the areas highlighted in the map are on the tip or outer edges of the tongue. This would seem to indicate that the majority of the tongue doesn’t have taste receptors at all, which is a fairly ludicrous notion. Also, while there were only four accepted basic tastes when the map was originally created, in 1990 umami, or savory, was internationally accepted as the fifth basic taste. To solve this little problem, the blank center of the tongue was simply labeled as umami, even though that taste was never tested for as part of the original research.

Of course, it’s largely irrelevant because the map is utter and complete nonsense. It was created as the gross misinterpretation of research that had been produced decades earlier. The tongue map traces its origins back to psychologist Dr. David P Hänig’s 1901 paper Zur Psychophysik des Geschmackssinnes, or “on the psychophysics of the sense of taste”. During his research, Hänig sought to taste the threshold for taste on the periphery of the tongue. It had been observed that the edges of the tongue were more sensitive to taste because of their abundant taste buds, and Hänig was simply trying to do some measurements to quantify that phenomenon.

In his paper was a diagram that looks very similar to the modern tongue map. Instead of the sections being labeled by the different flavours, they were simply labeled with the numbers 1 through 4, with each area being slightly more receptive to taste than the previous. These differences were minute to the point of being irrelevant from a practical standpoint, but they technically did exist.

However, the sections of the tongue in the diagram had nothing to do with different tastes, just the minimum threshold of stimuli at which taste could be sensed. It was just meant as an artistic rendition of the data he had collected.

Unfortunately, a copy of this paper wound up in the hands of Harvard psychology professor Edwin G. Boring. We could potentially give Boring the benefit of the doubt, as perhaps he had a poor translation of the original German language paper. Or it could have been gross incompetence, there’s no way to know for sure which it was. But whatever the reason, when Boring published Sensation and Perception in the History of Experimental Psychology, he misinterpreted the four sections in Hänig’s diagram as each being exclusively, or at least predominantly, for one of the four basic tastes.

Boring published a new diagram with the sections labeled as bitter, sour, salty, and sweet in his 1940 book, and this diagram became the tongue map that has been promoted in science textbooks ever since. The map has been heavily refuted and disproven, but it persists in textbooks to this day.

You Lose 80% Of Your Heat Through Your Head

This is probably more in the realm of common knowledge than something that frequently appears in textbooks, but it’s still something that is likely to be taught to students preparing to go outside for a recess on a chilly day. The idea is that you lose a large amount of heat through your head. Exactly how much heat is lost through the head can range from the vague answer of “the majority of it” all the way up to 80%, which seems to be the most commonly repeated number.

This startling and surprising fact is used as evidence that it’s always important to wear a hat, so students had best be bundled up before going outside to play. While it’s certainly good advice to dress appropriately for the weather, this specific claim doesn’t hold up to even the most basic examination.

According to the oft recited fact, a person who was wearing winter clothes but no hat would lose more heat than someone who wore a hat but was otherwise butt ass naked. That obviously doesn’t make the tiniest bit of sense, so where did this erroneous information come from?

That would be from the US military, at least to an extent. The earliest source of this myth that everyone points to is a 1970 US Army survival manual. The manual stated that 40-45% of the body’s heat was lost through the head. It’s not clear how that number got inflated to 80%, but even the 40-45% number is absurd.

In the previous example of a hatless person and a person wearing nothing but a hat, they would be losing roughly the same amount of body heat. That still doesn’t make sense, so how did the Army come to this conclusion?

It can be traced back to an experiment conducted by military researchers in the 1950s. During the experiment, volunteers were dressed in arctic survival suits and their bodies were measured for heat transfer to the environment. But the survival suits had little to no covering for the head, so 40-45% of the body heat being lost was lost through the head. Note that the claim was not that they were losing that percentage of total body heat, just that of the heat that was lost while their bodies were fully covered in arctic gear, about half of the loss was through their exposed heads.

That data makes a lot more sense, as exposed parts of the body will obviously lose more heat than those that are covered. The myth was created by a misinterpretation of this data, and it quickly spread. After all, parents were still telling their children that they’d catch a cold if they went outside with wet hair, so this information only further validated something that they already believed.

But more recent research has shown that this belief was completely false. A person does not lose 40, 45, or 80% of their body heat through their head, they lose about 10%. Not at all coincidentally, the head is roughly 10% of the surface area of an adult body. Data consistently showed that the heat loss was always proportional to the surface area of the exposed body parts.

Oh, and if it wasn’t clear before, you in fact will not catch a cold by going outside in the winter with wet hair. You will just have cold wet hair.

Key Takeaways

• Schools often teach oversimplified or outdated scientific concepts for simplicity.
• Deoxygenated blood is not blue; veins appear blue due to light scattering.
• Eating carrots maintains eye health but does not improve vision in healthy individuals.
• Humans have more than five senses, with modern science recognizing up to 33.
• The myth that 80% of body heat is lost through the head is false.

Sources

• Original Side Projects video: Scientific Concepts You’re Taught in School Which are Actually Wrong
• Hero image source by L. David Mech / openverse, by-sa.

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