We all have them, yet our bodies are often a source of mystery. Some biological functions truly are perplexing — we still don’t know exactly why we dream or why we cry when we’re emotional, for example. But others have given rise to persistent myths, despite decades of debunking by scientists. Here are just a few common beliefs about the human body that you might be surprised aren’t true.
In the fourth century BCE, Aristotle identified five — and only five — senses: sight, smell, taste, hearing, and touch. Over the past 2,000 years, though, we’ve learned much more about our ability to perceive and process our surroundings. Some researchers have suggested we have 21 or more senses based on the types of receptors contained in our sensory organs. For example, we have mechanoreception, which includes the sense of balance; perception of hot and cold temperatures; receptors to taste bitter, sweet, salty, sour, and umami flavors; and even interoceptors for sensing blood pressure and lung inflation.
Humans are born with about 100 billion brain cells. Until the 1990s, most scientists believed 100 billion was all we’d ever have. Growing new neurons would interrupt communication among our existing brain cells and short-circuit the whole system — or so the theory went. Then, a 1998 study found evidence that humans could generate new cells in the brain’s hippocampus, an area associated with learning and memory. More recent studies have largely supported the idea, and suggest that we might be able to make up to 1,500 neurons a day. Though research continues, neurogenesis is good news: Growing fresh neurons may make our brains more resilient against Alzheimer’s, depression, anxiety, and other disorders.
Myth: Speaking of Brains, We Use Only 10% of Them at a Time
Maybe you’ve heard peppy TED Talk speakers say that our brains have limitless potential… if only we could employ them to their fullest extent. They might have been referring to the myth that we use just 10% of our brain power at a given time. This old chestnut probably grew from a 1907 article for the journal Science by William James, one of the founders of modern psychology. “Compared with what we ought to be, we are only half awake… we are making use of only a small part of our possible mental and physical resources,” he wrote. Dale Carnegie cited James in How to Win Friends and Influence People, his 1936 self-help bestseller. Eventually, someone — it isn’t clear who — claimed we were ignoring 90% of our mental powers. But there’s no scientific basis for the belief.
Myth: You Need to Drink Eight Glasses of Water a Day to Stay Hydrated
Mild dehydration can make you sluggish and dizzy, while a serious case can lead to organ damage. But there’s little evidence to suggest that eight 8-ounce glasses of water per day is the ideal amount to maintain health. This well-known myth likely arose from a 1945 government health bulletin, which claimed that “a suitable allowance of water for adults is usually 2.5 liters daily … Most of this quantity is contained in prepared foods.” Over time, people overlooked that second sentence and assumed the guidelines called for 2.5 liters per day in addition to water contained in foods. Today, dietitians say that the optimum amount of water intake per day varies from person to person, but that most of it should come from food sources like fresh fruits and vegetables.
You’ve probably heard adults admonish kids to wait a half-hour (or longer) after a meal before jumping back in the pool. Generations of people have believed that, soon after eating, blood is diverted from the limbs toward the gut to aid digestion. Swimming too soon would supposedly cause your stomach or extremities to cramp up, which could lead to drowning. In 2011, the Red Cross published a thorough investigation of the scientific literature and found no link between eating and drowning, concluding that “food intake restrictions prior to swimming are unnecessary.” On the other hand, you may want to wait for your lunch to settle before trying that backflip off the diving board.
Low temperatures alone can’t make you sick — you’re going to need a virus for that. The pervasive sense that cold weather causes colds stems from a few coinciding factors. One, viruses that cause the common cold are more active and resilient in winter in many parts of the world. Two, cold temperatures outside keep more people inside, where you might pick up someone else’s virus (and indoor heating can dry out your sinuses, making it easier for viruses to invade). Three, cold weather may also slow down your normal immune responses. All of these scenarios add up to a greater risk of being exposed to a virus that has a better chance of making you sick.
And while we’re on the topic, the myth that you should feed a cold (and starve a fever) probably arose in the medieval era, when people “treated” colds by raising a patient’s body temperature with hot meals. People also believed that fevers could be “cooled down” by depriving the body of food. In fact, bodies fighting both kinds of illnesses need proper nourishment, as well as rest and fluids.
Interesting Facts
Editorial
Interesting Facts writers have been seen in Popular Mechanics, Mental Floss, A+E Networks, and more. They’re fascinated by history, science, food, culture, and the world around them.
Advertisement
top picks from the optimism network
Interesting Facts is part of Optimism, which publishes content that uplifts, informs, and inspires.
It’s easy to take our bodies for granted, but they’re home to an array of wonders. Consider, for example, that our eyes can see distant galaxies, our hair contains traces of gold, and our veins could stretch for 60,000 miles if laid end to end — that’s enough to go around the world twice. Below, we’ve gathered some of our most fascinating facts about the human body from around the website. They just might help you see your anatomy in a whole new, and more wondrous, light.
Humans are born with about 100 billion brain cells. Until the 1990s, most scientists believed 100 billion was all we’d ever have. Growing new neurons would interrupt communication among our existing brain cells and short-circuit the whole system — or so the theory went. Then, a 1998 study found evidence that humans could generate new cells in the brain’s hippocampus, an area associated with learning and memory. More recent studies have largely supported the idea, and suggest that we might be able to make up to 1,500 neurons a day. Though research continues, neurogenesis is good news: Growing fresh neurons may make our brains more resilient against Alzheimer’s, depression, anxiety, and other disorders.
While most people dream in full color, around 12% of the population is tuned to Turner Classic Movies (so to speak), and often experiences dreams in only black and white.
The analogy to television is an apt one, as researchers discovered in 2008 that people under the age of 25 almost never dreamed in monochrome, while members of the boomer generation and older had dreams devoid of color roughly a quarter of the time. Although it is difficult to prove definitively that TV is to blame, the number of people who reportedly dream in grayscale has slowly fallen over the decades.
Gravity is an essential force on Earth: It keeps the planet in orbit at a safe and comfortable distance from the sun, and even holds our atmosphere in place. It does have a downside, however: It weighs down the human body, making us a tiny bit shorter by the end of the day. From the moment we climb out of bed in the morning, gravitational forces push down on us, applying downward pressure on our joints, compressing our spines, and causing our organs to settle. All that strain adds up, enough to shrink a body by 1 centimeter. Gravity is at work whether we’re sitting or standing, but at bedtime, our bodies get a slight reprieve as lying down redirects the force. Sleeping horizontally gives our spines and joints time to decompress and gain back the height lost during the day, making us once again slightly taller by morning.
Much of the work of perceiving the world around us actually takes place in the brain. In a way, our eyes act as a camera, and our brains as a kind of “darkroom” that develops that information into what we call our vision. One of the most perplexing aspects of this dual relationship is that the images projected onto our retina are actually upside-down. Because the cornea — the transparent part of the eye covering the iris and pupil — is a convex lens, when light enters the cornea, it’s flipped upside down. It’s the brain’s job to translate this inverted information, as well as two 2D images, one from each eye, into one cohesive 3D image.
Gold is present in low levels throughout the Earth; it’s been found on every continent except Antarctica, as well as in the planet’s core, the oceans, plants, and in humans, too. The average human body of about 150 pounds is said to contain about .2 milligrams of gold, which we excrete through our skin and hair. Babies less than 3 months old tend to have more gold in their manes than older people, thanks to the precious metal being passed along in human breast milk. And while no one’s suggesting we should mine the gold in hair or breast milk (as far as we know), researchers are studying whether gold — and other metals — might be recovered from human waste.
By the time most of us reach age 20 or so, the bones in our body are pretty much done growing. The growth plates that caused us to put on inches in our youth are now hardened bone, and in fact, adults tend to drop an inch or two in height as worn-out cartilage causes our spines to shrink over time. However, there are a few bones that buck this biological trend. Skulls, for example, never fully stop growing, and the bones also shift as we age. A 2008 study from Duke University determined that as we grow older, the forehead moves forward, while cheek bones tend to move backward. As the skull tilts forward, overlying skin droops and sags.
The skull isn’t the only bone that has a positive correlation with age. Human hips also continue to widen as the decades pass, meaning those extra inches aren’t only due to a loss of youthful metabolism. In 2011, researchers from the University of North Carolina School of Medicine discovered that hips continue to grow well into our 70s, and found that an average 79-year-old’s pelvic width was 1 inch wider than an average 20-year-old’s.
Human eyes are entirely unique; just like fingerprints, no two sets are alike. But some genetic anomalies create especially unlikely “windows” to the world — like gray eyes. Eye experts once believed that human eyes could appear in only three colors: brown, blue, and green, sometimes with hazel or amber added. More recently, the ashy hue that was once lumped into the blue category has been regrouped as its own, albeit rarely seen, color. Brown-eyed folks are in good company, with up to 80% of the global population sporting the shade, while blue eyes are the second most common hue. Traditionally, green was considered the least common eye color, though researchers now say gray is the most rare, with less than 1% of the population seeing through steel-colored eyes.
You Breathe Primarily Out of One Nostril at a Time
The human nose can smell up to 1 trillion odors, trap harmful debris in the air before it enters your lungs, and affect your sex life. But arguably its most important job is to condition the air you breathe before that air enters your respiratory tract. This means warming and humidifying the air before it passes to your throat and beyond. To do this, the nose undergoes a nasal cycle in which one nostril sucks in the majority of the air while the other nostril takes in the remaining portion. A few hours later (on average), the nostrils switch roles. This cycle is regulated by the body’s autonomic nervous system, which swells or deflates erectile tissue found in the nose.
Although we don’t notice this switch throughout the day, if you cover your nostrils with your thumb one at a time, you’ll likely observe that air flow through one is significantly higher than the other. This is also why one nostril tends to be more congested than the other when you have a cold.
The Human Eye Can See Objects Millions of Miles Away
While the majority of us wouldn’t consider our vision to be extraordinary, the human eye can see much farther than most of us realize. That’s because our ability to perceive an object is based not only on its size and proximity, but also on the brightness of the source. Practically speaking, our sight is hindered by factors such as atmospheric conditions and the Earth’s curvature, which creates the dropoff point of the horizon just 3 miles away. However, a trip outside on a clear night reveals the true power of our vision, since most of us are able to make out the faint haze of the Andromeda galaxy some 2.6 million light-years into space.
Bioluminescence, the strange biology that causes certain creatures to glow, is usually found at the darkest depths of the ocean where the sun’s light doesn’t reach. While these light-emitting animals seem otherworldly, the trait is actually pretty common — in fact, you’re probably glowing right now. According to researchers at Tohoku Institute of Technology in Japan, humans have their own bioluminescence, but at levels 1,000 times less than our eyes can detect. This subtle human light show, viewable thanks to ultra-sensitive cameras, is tied to our metabolism. Free radicals produced as part of our cell respiration interact with lipids and proteins in our bodies, and if they come in contact with a fluorescent chemical compound known as fluorophores, they can produce photons of light. This glow is mostly concentrated around our cheeks, forehead, and neck, and most common during the early afternoon hours, when our metabolism is at its busiest.
The Space Between Your Eyebrows Is Called the “Glabella”
You know hands, shoulders, knees, and toes (knees and toes), but has anyone ever introduced you to the glabella? This isn’t some hidden-away body part like the back of the elbow or something spleen-adjacent — it’s smack dab in the middle of your face. Latin for “smooth, hairless, bald,” the glabella is the small patch of skull nestled in the middle of your two superciliary arches (also known as your eyebrow ridges). Many people know of the glabella because of the wrinkles, or “glabellar lines,” that can appear in the area.
We Have Wisdom Teeth Because Our Ancestors Had to Chew More
Early humans were hunter-gatherers who survived on leaves, roots, meat, and nuts — things that required a lot of crushing ability. The more grinding teeth you have, the easier it is to eat tough foods. As humans evolved, they began to cook their food, making it softer and easier to chew. Having three full sets of molars became unnecessary.
Early humans also had larger jaws than we do today, which were able to support more teeth. Over time, as the need for super-powerful jaws decreased, human jaws got smaller. But the number of teeth stayed the same. That’s why today, many people need to get their wisdom teeth removed in order to create more space. Yet because wisdom teeth aren’t necessary for modern humans, they may someday cease to exist at all.
Researchers estimate that some 300 million people around the world are colorblind, most of them male. On the opposite end of the spectrum are those with an exceedingly rare genetic condition that allows them to see nearly 100 million colors — or 100 times as many as the rest of us. It’s called tetrachromacy, or “super vision,” and it’s the result of having four types of cone cells in the retina rather than the usual three. (Cones help our eyes detect light and are key to color vision.) Because of the way the condition is passed down via the X chromosome, the mutation occurs exclusively in women.
Maybe you’ve heard peppy TED Talk speakers say that our brains have limitless potential… if only we could employ them to their fullest extent. They might have been referring to the myth that we use just 10% of our brain power at a given time. This old chestnut probably grew from a 1907 article for the journal Science by William James, one of the founders of modern psychology. “Compared with what we ought to be, we are only half awake… we are making use of only a small part of our possible mental and physical resources,” he wrote. Dale Carnegie cited James in How to Win Friends and Influence People, his 1936 self-help bestseller. Eventually, someone — it isn’t clear who — claimed we were ignoring 90% of our mental powers. But there’s no scientific basis for the belief.
Babies Are Born With Almost 100 More Bones Than Adults
Babies pack a lot of bones in their tiny bodies — around 300, in fact, which is nearly 100 more than adult humans have. The reason for this is biologically genius: These extra bones, many of which are made entirely or partly of cartilage, help babies remain flexible in the womb and (most crucially) at birth, making it easier for them to pass through the birth canal. As a baby grows into childhood and eventually early adulthood, the cartilage ossifies while other bones fuse together. This explains the “soft spots” in a baby’s skull, where the bones have yet to fuse completely.
If you’ve ever seen someone track their pulse (in real life or on a crime drama), you’ll notice that the index and middle fingers are always pressed on the neck’s carotid artery, which is responsible for transporting blood to the brain. There’s a reason why doctors (and actors who play doctors on TV) use these fingers and not, say, their thumbs. While your thumb is good for many things, taking your pulse isn’t one of them. Unlike the other four digits, the thumb has its own exclusive artery, the princeps pollicis, which makes it biologically unreliable as a pulse reader — because you’ll feel it pulse instead of the artery in your neck.
We’ve all heard that we have five senses: sight, smell, hearing, touch, and taste. That idea goes back to the Greek philosopher Aristotle — but it’s wrong. Modern science has identified as many as 32 senses, by looking at receptors in our bodies with the job of receiving and conveying specific information. Senses you might not know you have include your vestibular sense, which controls balance and orientation; proprioception, which governs how our bodies occupy space; thermoception, which monitors temperature; nociception, our sense of pain; and many more.
Cilantro Tastes Like Soap to Some People Because of Their Genes
Many gourmands enjoy topping their fish, salads, and soups with a smattering of cilantro, while the herb makes others feel like they’re biting into a bar of Ivory Spring. The reason appears to be a matter of genetics. One 2012 study showed that people equipped with certain olfactory receptor genes are more prone to detecting cilantro’s aldehydes, compounds also commonly found in household cleaning agents and perfumes. While the percentage of the population that suffers from this fate tops out at about 20%, the resulting taste is apparently awful enough to spark passionate responses of the sort found on Facebook’s I Hate Cilantro page, which has more than 26,000 likes at the time of writing.
All humans demonstrate the same expressions for emotions the world over, according to body language expert David Matsumoto. That’s because we all generally have the same facial muscles and structure, regardless of age, sex, ethnicity, or culture. However, culture helps determine what emotions are expressed when — and how those expressions are perceived.
There are some surprising lengths packed inside the human body. The small intestine, for example, could stretch 22 feet end to end (though hopefully it never has to). Not to be outdone, our nerves could stretch 37 miles if laid end to end. However, none of this compares to our circulatory system. According to the British Heart Foundation, the veins in an adult human could stretch an astonishing 60,000 miles — that’s farther than it takes to circumnavigate the globe twice. Capillaries, which transport blood between arteries and veins, make up 80% of this length.
There are 206 bones in the average adult human body, and our hands take up the lion’s share. Each hand is home to 27 bones, along with 34 muscles and 123 ligaments. Some experts estimate that a quarter of the motor cortex, the part of the brain responsible for voluntary movement, is devoted to the manipulation of our hands alone.
Although hands are impressive structures, they only just beat our feet by one bone. Because Homo sapiens’ primate ancestors walked on all fours, human hands and feet developed in similar ways. In fact, almost every bone in the palm is arranged in a pattern similar to the metatarsals in the foot. The only exception is a bone located at the edge of the wrist called the pisiform, which attaches various ligaments and tendons.
After birth, a baby mostly sees in black and white — and that’s only the beginning of its problems. A newborn’s vision is also incredibly fuzzy, and limited to around 8 to 12 inches from its face during the first few weeks of life. Whereas average human sight is considered 20/20, it’s estimated that a newborn’s vision lies somewhere between 20/200 and 20/400. Because red has the longest wavelength (at 700 nanometers), the color doesn’t scatter easily, and it’s the first hue capable of being detected by a baby’s reduced visual range. Fortunately, most babies have attained most of the normal human visual faculties within a year from birth.
Your “funny bone,” named as such for its location near the humerus bone — “humorous,” get it? — is not really a bone at all. Rather, it’s part of the ulnar nerve, which runs from your neck all the way to your hand. Nerves are usually protected by bone, muscle, and fat, so they can perform their bioelectrical functions undisturbed, but a small part of the ulnar nerve in the back of the elbow is a little more exposed. There, the nerve is protected only by a tunnel of tissue, known as the cubital tunnel, so when you hit your “funny bone,” the ulnar nerve presses against the medial epicondyle (one of the knobby ends of the humerus bone), which in turn sends a painful sensation throughout your lower arm and hand. And because the nerve gives feeling to the pinky and ring fingers, those two digits may feel particularly sensitive compared to your other three fingers.
Our tongues, like our fingerprints, are specific to each individual. That’s right — people have tongue prints, which vary from one person to another due to both shape and texture. And perhaps surprisingly, the organ has been gaining some popularity as a method for biometric authentication. Where fingerprints can be altered, eyes affected by astigmatisms or cataracts, and voices changed just by the all-too-common cold, the human tongue is relatively protected from external factors. Sticking out one’s tongue for a print also involves a layer of conscious control and consent that goes beyond what’s required for retinal scans or even fingerprinting, which could make it a more appealing biometric tool. In fact, these “lingual impressions” may be so advantageous over other forms of authentication that some researchers have started investigating the idea of a tongue print database, using high-resolution digital cameras to record every ridge, line, and contour of that muscular organ in our mouths.
The involuntary spasmodic interruptions known as hiccups usually last only a few minutes. Then there’s the strange case of Charles Osborne, who was afflicted with a continuous case of hiccups for 68 years — recognized by Guinness World Records as the longest case of hiccups in history.
Osborne’s story began with an accident on June 13, 1922, in which he accidentally slipped and fell. His doctor later said he popped a blood vessel in his brain the size of a pin, and theorized that Osborne must have damaged the incredibly small area of the brain that controls and inhibits hiccups. Osborne’s diaphragm spasmed 20 to 40 times a minute, on average, during his waking hours — meaning he hiccuped roughly 430 million times throughout his life. To cope with this never-before-seen disorder, Osborne learned breathing techniques that effectively masked his constant hiccuping. Although he traveled the world in search of a cure — even offering $10,000 to anyone who could find one — the best he could do was cope with the affliction. Finally, in 1990, his diaphragm suddenly ended its 68-year-long spasmodic episode on its own. Osborne died less than a year later, but he was at least able to experience the final days of his life sans hiccups.
Interesting Facts
Editorial
Interesting Facts writers have been seen in Popular Mechanics, Mental Floss, A+E Networks, and more. They’re fascinated by history, science, food, culture, and the world around them.
Advertisement
top picks from the optimism network
Interesting Facts is part of Optimism, which publishes content that uplifts, informs, and inspires.
The color green is intimately tied to the human experience. The hue fills our world as the color of nature, and its particular wavelength has a fascinating relationship with our visual sense. The color can represent positive notions (peace and fertility) as well as negative ones (greed or envy). Although it’s considered a secondary color, because it’s a mix of both yellow and blue primary colors, green is maybe the most important hue in the visual spectrum — and these five mind-blowing facts explain why.
Human Eyes Are Most Sensitive to the Green Wavelength of Light
Electromagnetic radiation comes in a variety of types, including radio waves, gamma rays, and visible light. The human eye can perceive wavelengths around 380 to 740 nanometers (nm), also known as the visual light range. The size of the wavelength determines the color we see: For example, at 400 nm our eyes perceive the color violet (hence the name “ultraviolet” for wavelengths directly under 400 nm), whereas at 700 nm our eyes glimpse red (but can’t see the “infrared” wavelengths just beyond it). In the middle of this spectrum of visible light is the color green, which occupies the range between 520 to 565 nm and peaks at 555 nm. Because this is right in the middle of our visual range, our eyes are particularly sensitive to the color under normal lighting conditions, which means we can more readily differentiate among different shades of green. Scientists have also found that the color green positively affects our mood in part because our visual system doesn’t strain to perceive the color — which allows our nervous system to relax.
Credit: Leemage/ Corbis Historical via Getty Images
The Color Green Has Meant Many Things Throughout History
Today, the color green is associated with a variety of feelings and social movements. Turning a shade of green can indicate nausea, but you can also become “green” with envy. Green is closely associated with money and capitalism, while also embodying aspects of nature and the environmentalist, or “Green,” movement.
However, these cultural definitions have changed over millennia, and have different associations in different parts of the world. For example, in ancient Egypt, green was often linked with both vegetation and death, and Osiris (god of fertility and death) was often depicted as having green skin. These days, green is prevalent throughout the Muslim world — adorning the flags of Muslim-majority nations such as Iran and Saudi Arabia — because it was supposedly the prophet Mohammad’s favorite color. Many African nations also include the color green in their flags to represent the natural wealth of their continent, and Confucius believed green (more specifically jade) represented 11 separate virtues, including benevolence, music, and intelligence.
Hollywood Uses Green Screens Because of Human Skin Tones
If you’ve seen any big-budget Hollywood film, it probably used some variety of green screen-enabled special effects. In fact, some version of green screen technology, also known as “chroma keying,” has been around since the early days of film. The reason why screens are green is actually pretty simple — human skin is not green. When a camera analyzes chrominance, or color information, it can easily separate green (or blue) from the rest of the shot so that a video backdrop can be inserted.
The Color Green May Have Killed Napoleon Bonaparte
In 1775, German Swedish chemist Carl Wilhelm Scheele made a green-hued pigment that eventually bore his name — Scheele’s green. Unfortunately, the pigment was extremely dangerous, since it was made with arsenic. However, its rich hue ignited a craze for green, and the pigment was used in wallpaper, clothing, and even children’s toys. In fact, some historians believe that Napoleon Bonaparte died from the Scheele’s green pigment embedded in the wallpaper of his bedroom on the island of St. Helena.
However, that wasn’t the end of green’s deadly reputation. Decades later, impressionist painters — such as Paul Cézanne and Claude Monet — used a green pigment called Paris green that was highly toxic, if less dangerous than Scheele’s green. Experts suggest that the chemical could have contributed to Cézanne’s diabetes and Monet’s blindness.
No One Is Sure Why the Backstage Room Is Called a “Green Room”
One early reference to a “green room” in the sense of a waiting room appears in TheDiary of Samuel Pepys, the famed journal kept by a civil servant in 1660s London. Pepys mentions a “green room” when going to meet the royal family — likely a reference to the color of the walls. A “green room” was then tied to the theater in English playwright Thomas Shadwell’s 1678 comedy A True Widow, which includes the line: “Selfish, this Evening, in a green Room, behind the Scenes.” However, Shadwell doesn’t mention why it was called a green room. One notable London theater did have a dressing room covered in green fabric, but other theories behind the term reference actors going “green” because of nervousness, amateur or young (aka “green”) actors, or a place where early actors literally waited “on the green” lawns of outdoor theaters — among many other ideas. It’s possible we’ll never know the origin of the phrase for sure.
Darren Orf
Writer
Darren Orf lives in Portland, has a cat, and writes about all things science and climate. You can find his previous work at Popular Mechanics, Inverse, Gizmodo, and Paste, among others.
Advertisement
top picks from the optimism network
Interesting Facts is part of Optimism, which publishes content that uplifts, informs, and inspires.
The human body contains around 600 muscles, more than 200 bones, and all sorts of tendons, fascia, and organs — but some of them are pretty much obsolete, even if they make for decent party tricks. A few body parts have even started to disappear already, and are only present in certain segments of the population. In extreme cases, as people who have had appendectomies or wisdom tooth extractions can attest, it seems like some of these body parts exist only to hurt us.
Are you missing a mostly useless arm muscle? What muscles are key for dogs, but not particularly handy for us? These seven body parts are pretty much just along for the ride.
The appendix, a small pouch attached to the large intestine, is perhaps the best-known useless organ, doing little except occasionally getting infected. However, it turns out that it might not be entirely useless. Scientific theories have been floating around since 2007 that the appendix might actually serve as a “safe house” for beneficial gut bacteria, storing it to replenish it in the rest of the gut if it gets wiped out by illness (or, in modern times, antibiotics).
If this turns out to be accurate, it’s still not a particularly important organ, and if it gets severely infected, you still need to get it removed. Don’t worry: Hundreds of thousands of people get them taken out every year and are doing just fine.
Humans don’t need tails, but our ancestors sure did — and tailbones, also known as coccyxes, are the last remaining part of them, consisting of three to five vertebrae that aren’t connected to the spine. The coccyx is not a functional tail, but it is woven in with the ligaments, tendons, and muscles in the area. Occasionally, it gets rid of itself by fusing with the sacrum, another lower back bone. In cases of extreme pain that don’t resolve with any other treatment, people can get their coccyx surgically removed, but it’s unnecessary in the vast majority of cases. Occasionally a baby will be born with an actualtail — and human embryos generally form with a tail that later disappears as it grows into the tailbone — but it’s extremely rare.
Wisdom teeth, a third set of molars, have made dental surgery a rite of passage. For those who get them — many people don’t — they usually start emerging between the ages of 17 and 21. Often, there’s no room in the jaw, and the teeth end up trapped. When that happens, they need to be surgically extracted. Occasionally they grow in without incident and just become extra teeth.
It’s a lot of trouble for a set of teeth that we don’t even need. One theory is that our ancestors, who ate harder-to-chew things and didn’t have dentists, needed them as backup teeth. Modern science has gotten pretty good at just replacing teeth as they fall out, but wisdom teeth could still replace damaged molars in a pinch.
If you have a pet dog or cat, you’ve probably noticed their ears snapping to attention at an interesting or startling noise. Humans still have those muscles and, likely, the brain circuits associated with them. In one study, researchers observed tiny, involuntary movements in the directions of interesting sounds. For one part of the study, they had participants read a boring text while they played attention-grabbing sounds like crying babies and footsteps. Next, they had participants try to listen to a podcast while a second podcast played in the background. Those ear muscles fired up in both cases — they’re just obsolete for modern human beings. Some humans can still wiggle their ears, which does serve one purpose: It’s a cool party trick.
Some emerging research suggests these muscles may have a role in combating hair loss — and without them, we wouldn’t have a name for the iconic children’s horror series Goosebumps — but as far as basic survival goes, the arrectores pilorum are pretty much useless.
Most animals have a third eyelid, also called the nictitating membrane, which serves as a kind of windshield wiper that distributes tears and clears debris from the eye. This trait evolved out of human beings and some apes, but we still have a tiny vestigial remnant in the inner corners of our eyes. It’s a bit of eye tissue just inside that fleshy pink eye bump. In exceedingly rare cases — only two have ever been reported — humans can have a more developed nictitating membrane that covers a larger portion of the eye.
So why did we lose ours? One theory is that, unlike animals that still have them, we’re not typically sticking our faces directly into bushes or other animals to forage for food, so we have less debris to push out of our eyes.
The palmaris longus is a muscle stretching the length of our forearm that’s evolving away before our very eyes, literally — because it’s visible when you hold your hand and wrist a certain way, you can actually tell whether you still have yours on sight. It’s already missing in a significant portion of the population, and different studies around the world have observed its disappearance in anywhere between 1.5% and 63.9% of participants.
The muscle helps with wrist flexion in those who still have it, but it’s getting progressively weaker as other muscles take over its duties. If you don’t have one, you can still do all the same things as someone who does have it. While it’s unnecessary as is, the palmaris longus is pretty useful as a donor tendon for plastic surgery.
Sarah Anne Lloyd
Writer
Sarah Anne Lloyd is a freelance writer whose work covers a bit of everything, including politics, design, the environment, and yoga. Her work has appeared in Curbed, the Seattle Times, the Stranger, the Verge, and others.
Advertisement
top picks from the optimism network
Interesting Facts is part of Optimism, which publishes content that uplifts, informs, and inspires.
Whether bright orange, auburn, or more of a strawberry blond, red hair is a real eye-catcher. Celtic countries, like Scotland and Ireland, are most commonly associated with red hair, but fiery locks can pop up in people of multiple ethnicities around the world. Still, natural redheads are relatively rare — only one or two out of every 100 people can claim this distinction.
What makes red hair red? In what other ways are redheads unique? Which famous people are secret gingers… and which famous redheads are secret brunettes? Read on for 12 fabulous facts about carrot tops.
The difference between red hair and hair of other hues extends beyond just its color. On average, redheads have fewer hair strands overall compared to blonds and brunettes. Blonds, for example, have an average of around 150,000 strands of hair on their heads, whereas redheads have only 90,000 or so. Luckily, red hair tends to be coarser and thicker, so the discrepancy is not easily noticeable. Redheads also remain distinct from others as they age because red hair doesn’t go gray — instead, it turns silver or white.
Our genes make up a lot of who we are, including our looks. When people have red hair, it’s typically the MC1R gene that’s responsible.
The color of your hair comes from two possible pigments. Eumelanin makes your hair light or dark; people with black hair have a lot of it, while blonds don’t. The second pigment is pheomelanin, which is a redder pigment. Usually people don’t have a lot of the latter, because the MC1R gene converts pheomelanin into eumelanin. Redheads have a mutation in their MC1R gene that allows the pheomelanin — and the bright red color that comes with it — to flow free.
In order for someone to inherit red hair, both their parents need a mutated MC1R gene — and even then there’s about a 1-4 chance of redheadedness. Non-redheads can be redheaded gene carriers and not know it, although there are some ways to guess.
Auld Reekie, otherwise known as Edinburgh, likely has the highest concentration of redheads in the world. A DNA analysis conducted in 2014 discovered that 40% of people in the southeast region of Scotland, which contains the Scottish capital of Edinburgh, had variants of the red-haired gene. (Notably, they didn’t necessarily have red hair themselves, since the gene is recessive.) That percentage is higher than in any other region of Scotland, or the world. Of course, the area known as Scotland today has long been associated with red hair (though it’s believed the mutation first took place in central Asia).
The Two Most Powerful Tudor Monarchs Were Redheads
The Tudor dynasty, which ruled England from 1485 until the death of Queen Elizabeth I in 1603, sported a whole family of redheads, chief among them Henry VIII and the “Virgin Queen” herself.
King Henry was described as strong, broad-shouldered, and possessing golden-red hair. His daughter with Anne Boleyn (also sometimes described as having auburn hair), who became Queen Elizabeth I in 1558, similarly sported a fiery mane. However, Queen Elizabeth I took the fashion for red hair to a whole new level. Although red hair was often associated with barbarians — and the Irish and Scots, with whom England constantly quarreled, were seen as descended from such barbarians — the queen made the hue so popular that English courtiers allegedly dyed their hair and beards red to show support for her (and also the Protestant cause).
Credit: Brian Dowling/ Getty Images Entertainment via Getty Images
There’s an Annual Festival in the Netherlands That Celebrates Redheads
Every year, thousands of ruddy-haired people descend on Tilburg, Netherlands, for the Redhead Days Festival. Spread across three days, the event offers workshops on make-up and skin care tips as well as photo shoots and meet-and-greets. These events can be particularly impactful for people with red hair, as research in 2014 found that 90% of redheaded males experienced bullying simply because of their hair color. The event began by accident in 2005 when a local amateur painter placed an ad in a Dutch newspaper for 15 redheaded models — and 10 times that number showed up. The event was so popular that the redhead meet-up became an annual tradition and then a full-fledged festival. At the 2013 meet-up, 1,672 redheads set the world record for the largest gathering of people with natural red hair.
Portraits of George Washington often feature an elder statesman with powdered white hair (as was custom in the 18th century). However, as a young man, Washington actually had reddish-brown hair, as captured by portraits painted of him when he was younger. One example can be seen in the painting The Courtship of Washington, depicting Washington with his wife, Martha, and her two children (Washington never had biological children of his own). Even though the painting was completed some 60 years after Washington’s death, biographer Ron Chernow confirms that this was likely Washington’s true hair color. Mount Vernon, George Washington’s estate, even has a lock of his hair that displays the amber hue.
Despite a Persistent Myth, Redheads Are Not Going Extinct
In 2007, an article by an unnamed geneticist posited that redheads are going extinct. Despite many experts’ assertions to the contrary, the myth has persisted — but thankfully, no such extinction is on the horizon. This myth comes from the idea that recessive genes can essentially die out. If people with this rare genetic mutation (about 1% to 2% of the population) don’t have children, the color red will slowly fade away, or so the idea goes.
However, that’s not quite how genetics works. While only a few people (around 70 million to 140 million) sport red hair, many more are carriers of the gene, and it’s not uncommon for the red hair gene to skip a generation. Despite being carried through recessive genes, red hair color is genetically stable, meaning that evolution would need to select red hair as disadvantageous for some reason in order for it to become extinct. So no need to worry — red hair is here to stay.
Those With Freckles May Be Redheaded Gene Carriers
Carrying two MC1R gene mutations can cause redheadedness, but even people with only one mutation are three times as likely to develop ephelides, the medical term for what most of us think of as freckles, compared to those without any MC1R mutations. If you’re carrying two mutated MC1R genes, you’re 11 times more likely to get them. So if you have a light dusting of freckles across your nose (and they’re not just tattoos), your future child might be redheaded — even if your hair is blond or black. (Unfortunately, you also have a higher risk of developing skin cancer.)
The most familiar photos of Samuel Clemens, better known under his pen name Mark Twain, are not just in black and white, but also taken when he’s older. So it’s easy to miss that as a young man, Twain had vibrant redhair, which went gray in his 50s.
Before color photography, hair looked either light or dark — so many historical redheads are hiding in plain sight. Other redheads we’re not used to seeing in color include former U.S. President Calvin Coolidge and Dracula author Bram Stoker.
Lucille Ball was one of Hollywood’s most iconic redheads, but she was actually a natural brunette. She went blond early in her career, when she was only appearing in black and white movies — but when she was cast as the lead in her first technicolor role, 1943’s DuBarry Was a Lady, she made the switch.
Still, that red wasn’t really the same red that she became known for. Hairstylist Sydney Guilaroff developed her famous shade a few years later to go better with her apricot-colored costume in Ziegfeld Follies (1946), using a few different dyes and a henna rinse.
While it’s easy to remember Ball in color, her best-known role as Lucy Ricardo on I Love Lucywas, of course, shot in black and white — although colorized versions exist.
Redheads May Produce More Vitamin D Than Other People
Our bodies generate vitamin D when the sun’s ultraviolet rays interact with our skin. This essential vitamin helps us absorb calcium and ward off a host of other health problems. Unfortunately, redheaded people tend to have fair, sensitive skin that doesn’t pair well with too much sunlight; it burns easily and is susceptible to skin cancer. Fortunately, redheads may produce more vitamin D with less sun than other people, according to a 2020 study from the Czech Republic, making up for at least some of that lost sunlight. No wonder the dark and rainy climes of Scotland and Ireland are full of them.
While results vary, multiple studies have found that people with redhead genes have a different response to pain than other people. In one 2005 study, they were able to withstand greater levels of electrical current and were more sensitive to opioid medications. A separate 2005 study found they were more sensitive to pain from heat or cold, and also tested sensitivity to the anesthetic lidocaine. That one found that when applied under the skin, lidocaine was less effective on redheads than other participants, which may mean redheads sometimes need more anesthesia.
The evidence is far from conclusive, however. A more recent study, this one from 2020, concluded that MC1R genes do affect pain, but not the same variants that affect hair color. All in all, it’s a fascinating look at what one gene can do.
Darren Orf
Writer
Darren Orf lives in Portland, has a cat, and writes about all things science and climate. You can find his previous work at Popular Mechanics, Inverse, Gizmodo, and Paste, among others.
Advertisement
top picks from the optimism network
Interesting Facts is part of Optimism, which publishes content that uplifts, informs, and inspires.
Twins are something of a natural phenomenon. While scientists understand the egg-splitting process that creates twins, researchers aren’t so sure why it happens. That fascination has been with humans for thousands of years — if you need proof, just look to the night sky, where the constellation Gemini (Latin for “twins”) shows how our interest in these duos has become part of both the astronomical and astrological world. Regardless of your own twin status or horoscope sign, you can celebrate these dynamic duos with the five facts about twins below.
The World Currently Has the Most Twins It’s Ever Had
Many humans know the joy (and occasional annoyance) of having siblings. But some of us have a particularly unique relationship thanks to being half of a twin set. Being born a twin is relatively rare; in the United States, just 3.2% of new deliveries are twin births. But while that number may seem low, the world is actually experiencing the largest number of twins in known human history, largely influenced by advances in assisted reproductive technology. Researchers believe the number of twins born each year has increased over the last five decades, particularly when it comes to fraternal twins. A 2021 survey of 165 countries — about 99% of the world’s population — found that 1 in 42 babies born today is a twin, a statistic that equates to 12 twin births for every 1,000 pregnancies. That number is up from the 1980s, when just nine sets of twins were born for every 1,000 pregnancies. And it adds up — scientists believe some 1.6 million twins are born each year.
Only 1 in 3 sets of twins are identical; the remaining two-thirds are considered fraternal, essentially siblings born at the same time who may or may not look alike. But even if identical twins seemingly appear as carbon copies, they do have some differences — such as their fingerprints. The patterns on our fingertips develop in utero, and how they look for the rest of our lives is heavily affected by our environment before birth. Blood pressure, umbilical cord length, and how fast a fetus grows all impact the final print design. Because identical twins share the same DNA, it’s likely their prints will be similar, though they’ll never be duplicates. In the history of fingerprint studies, no two people have ever had matching marks, including twins.
The city of Twinsburg lives up to its name each summer, beckoning thousands of twins to northwestern Ohio to celebrate their distinctive sibling relationships. Since 1976, the Twins Days Festival has been the world’s largest gathering place for twins. Event organizers believe more than 2,145 twins (and other multiples, like triplets and quadruplets) attended the three-day fest in 2022, participating in events like the twin talent show, parade, and award ceremony. The event has also come to serve another purpose — by gathering so many multiples in one place, scientists have a chance to collect data on twins’ genetic and behavioral similarities (and differences), giving researchers more insight into how our DNA and environment may play roles in our health and well-being.
Where You’re Born Increases Your Odds of Being a Twin
While the global number of twins is higher than ever before, there’s one part of the globe that holds the record for having the highest concentration of twins. Scientists believe the west coast of Africa, which includes countries such as Benin and Nigeria, beat the odds by a landslide on twin births. Studies from the 1970s on have pointed to both countries as the twin capitals, having anywhere from 27 to 40 sets of twins per every 1,000 births. It’s unclear to researchers why twins are more abundant in that region of the world, though doctors and citizens point to possible cultural factors, like the regional diet that includes okra leaves and yams (which may have plant compounds that play a role in maternal fertility).
Similarities and differences can be an endless topic of conversation for twins, though some research suggests that twins become less alike the older they get — at least, genetically. As they grow older, twins often make contrasting life choices and have different environmental exposures (aka interactions with chemical or biological substances, like cigarette smoke or UV radiation from the sun). This can cause differences in appearance or behavior as they age, or lead one twin to develop a medical condition the other does not have. A 2005 study from the Spanish National Cancer Center analyzed blood samples from twins and found that younger twins had more identical genes than older twins, especially those who lived apart — meaning that despite being born a duo, all twins eventually blaze their own paths in the world.
Nicole Garner Meeker
Writer
Nicole Garner Meeker is a writer and editor based in St. Louis. Her history, nature, and food stories have also appeared at Mental Floss and Better Report.
Advertisement
top picks from the optimism network
Interesting Facts is part of Optimism, which publishes content that uplifts, informs, and inspires.
There’s something magical about train travel for just about everybody, whether you’re an engineering nerd, a hopeless romantic, a world traveler, or an easily excitable 8-year-old. Trains have gone through a lot of changes in the last few centuries, but they remain one of the most common modes of transportation throughout the world.
How did trains work before steam power? Who managed to crash more than 140 trains in his lifetime? Which trains are creating homes for marine life off the coast of Delaware? All aboard for these nine facts about trains.
Before 1833, local time was all over the place; communities set their clocks to noon when the sun was highest in the sky, which led to at least 144 different local times in North America. This wasn’t a huge deal when people were traveling slowly by foot and horseback, but with trains, people could suddenly travel across wider distances more quickly — and train operators needed consistent schedules to coordinate. Even small miscommunications about time could lead to missed connections and accidents. Railroads established a four-time-zone system in 1833, and used it for decades before the U.S. government officially established time zones in 1918.
Japan’s bullet trains are known for their lightning speed, but a handful of trains have eclipsed them — one of them being Shanghai’s maglev train, which uses magnetic levitation instead of wheels on conventional tracks. Its entire 19-mile run takes just seven and a half minutes, reaching top speeds of 286 miles per hour.
That’s just the tip of the iceberg for maglev trains. The fastest recorded train speed is nearly 375 miles per hour, clocked during a test run of a maglev train in Japan.
The earliest railroad tracks were for horse-drawn trains, not locomotives. The tracks provided extra support and guidance, which meant that horses could carry greater loads. After the Liverpool and Manchester Railway opened with a steam-powered locomotive in 1830, jokes and cartoons about unemployed horses abounded, although horses were still used for shunting — moving trains from one line to another. Horses continued to haul streetcars into the 20th century.
Credit: George Rinhart/ Corbis Historical via Getty Images
America’s First Locomotive Reportedly Lost a Race to a Horse
When the Baltimore & Ohio Railroad — you might know it as the B&O Railroad — began operations in May 1830, it used only horse-drawn carriages. Steam locomotives were in use in Britain already, but because the planned system in America had steep hills and sharp curves, some engineers doubted that the machines could handle the route. This concerned B&O directors, so they turned to an inventor named Peter Cooper to see if he could create an engine that was up to the task. He cobbled one together out of scraps, including an old brass engine, discarded wheels, and musket barrels. Later dubbed “Tom Thumb,” it performed beautifully along a 7-mile test run, then again on a 13-mile test, reaching a then-impressive 18 miles per hour.
According to an 1868 lecture at the Maryland Institute by B&O lawyer John H.B. Latrobe, who was present on the 13-mile test, Tom Thumb also took part in a bit of a race. The owners of a stagecoach company saw the engine running along the track and challenged Cooper to a race along double tracks. The engine got an early lead, but a part slipped off, causing it to come to a halt. It was a quick fix, but by the time Cooper got going again, the horse was too far ahead. Losing the race didn’t have any effect on Tom Thumb’s future, though — he’d already impressed the B&O directors, who were determined to make the locomotive the way of the future.
In Victorian Times, Trains Were Considered Hazardous to Your Health
As train travel was starting to get popular in the mid-19th century, rumors spread — among doctors and nondoctors alike — that trains were dangerous, and not because of crash risks. All sorts of woes were attributed to the speed and roughness of locomotive travel. Some believed it could trigger insanity and create “railway madmen.” Others claimed it could cause miscarriages or upset women’s delicate constitutions. One doctor said that a train trip made a patient’s “brain congestion” worse, even though he’d been feeling better after treatment with leeches.
Credit: Mario Tama/ Getty Images News via Getty Images
New York’s MTA Turned Decommissioned Trains Into Artificial Reefs
When trains in New York City’s subway system get decommissioned, they can be sold, scrapped, or repurposed. Many of them can then be found on the ocean floor, providing homes for marine life as artificial reefs. Some car models work better than others; the Redbird cars, made of carbon steel, worked so well that states started competing for them. Redbird Reef in Delaware is home to around 700 such decommissioned cars, and they created a thriving ecosystem in an area that used to be barren. The stainless steel Brightliner cars, on the other hand, disintegrated almost immediately underwater — the material was vulnerable to corrosion, and their corrugated texture made it easy for currents to rip them apart.
It’s no fun getting caught at a railroad crossing and waiting for a long freight train to pass. But next time it happens, you can thank your lucky stars it’s not 4.57 miles long, like one train that ran in Western Australia in 2001. It was both the longest and heaviest train recorded. Pulled by eight locomotives, the 682 ore cars made a 171-mile journey transporting iron ore from a couple of mines run by mining company BHP to Port Hedlund.
Before there was demolition derby, there were staged, head-on train collisions. From the 1890s through the 1930s, train crashes were a popular attraction at fairs and festivals, drawing tens of thousands of spectators. One of the biggest wrecks was an 1896 publicity stunt in Waco, Texas, for a struggling railroad line known as the Katy Railroad. The company offered rides to the crash site for $2 from anywhere in Texas, and built a temporary town around the viewing area, complete with a restaurant and jail. The crash itself created a massive explosion, which sadly killed two people in the crowd.
This is just one of the most famous out of hundreds of on-purpose train collisions. The most prolific train-wrecker was Joe Connolly, otherwise known as “head-on Joe.” Between 1896 and 1932, Connolly staged 70 wrecks and destroyed 146 locomotives — at least. He became an engineer of chaos, coming up with extra stunts such as strapping dynamite to the trains. The practice, which came to be viewed as wasteful, fell out of favor during the Great Depression.
It Takes Almost a Week To Ride the Full Trans-Siberian Railroad
The longest single-train ride in the world is the Trans-Siberian Railroad. The main track starts in Moscow and travels 5,772 miles through diverse Russian landscapes before arriving in Vladivostok, a large port city on the sea of Japan. The full journey takes more than six days.
Other routes on the network are the Trans-Mongolian Railroad, which heads through Mongolia to Beijing, China, and the Trans-Manchurian Railroad, which dips down into northeastern China before meeting the main line back in Vladivostok.
Interesting Facts
Editorial
Interesting Facts writers have been seen in Popular Mechanics, Mental Floss, A+E Networks, and more. They’re fascinated by history, science, food, culture, and the world around them.
Advertisement
top picks from the optimism network
Interesting Facts is part of Optimism, which publishes content that uplifts, informs, and inspires.
You may think your upstairs neighbor’s 1 a.m. vacuuming session is noisy, but it’s nothing compared to what nature (and the occasional human-made marvel) can throw at us. Sounds can injure your ear immediately once they reach 120 decibels, the typical volume of a police siren if you’re right beside it, but the loudest sound ever recorded was more than 300, loud enough to increase atmospheric pressure to a point that causes damage to far more than just human ears.
Decibels are logarithmic measures of sound intensity — so keep in mind that the scale gets exponentially bigger as the number goes up. Doubling the volume on your stereo does not even come close to doubling the decibel output. So when an undersea creature produces a noise around 30 decibels higher than the loudest rocket launched by NASA (true story), you know you have a seriously big sound on your hands.
Which natural phenomenon produced the loudest known sound? What widely misunderstood sea giant generates an ear-shattering kind of Morse code? Just how loud is an asteroid impact? These six giant sounds will put that garage band next door in some serious context.
The loudest sound ever recorded was an 1883 volcanic eruption on the Indonesian island of Krakatoa, clocking in at an estimated 310 decibels. Not that anybody who heard the explosion at full blast lived to tell the tale; it was estimated to have a force equivalent to 10,000 times that of the atomic bomb dropped on Hiroshima, Japan, in 1945, and destroyed most of the island while shooting unstable clouds of hot gas to the surrounding area.
However, plenty of witnesses farther away did survive — and there were a lot of them. Some 100 miles away in North Jakarta, the noise still reached around 172 decibels. Violent tsunamis shook the Indian Ocean, and the waves even rocked boats in South Africa. Atmospheric pressure spikes reached as far as England, and a cloud of ash bathed an area of 300,000 square miles around the volcano in darkness. The global temperature even dropped, and didn’t return to normal until five years later.
The closest we’ve come to a repeat of Krakatoa was likely the Hunga Tonga-Hunga Ha’apai eruption near the Polynesian island of Tonga in January 2022. Sonic booms were felt as far north as Alaska, and researchers more than 6,000 miles away at Boise State University in Idaho recorded subterranean frequencies equivalent to about 100 decibels. The force, which was about half that of Krakatoa, sent a wave of pressure around the globe.
Fortunately, this blast wasn’t nearly as deadly, with three fatalities recorded compared to Krakatoa’s estimated 36,000. Still, it wreaked a lot of havoc. Tonga was largely cut off from the rest of the world for days, ash blanketed large swaths of the surrounding area, and tsunamis caused major damage along the coastlines. On one of the closer outlying islands, all the homes were destroyed. The volcano had created its own new island several years before; that was entirely obliterated, along with large chunks of two nearby islands.
Planet Earth is full of loud animals. Howler monkey cries can be as loud as gunshots, for example, and some species of bats emit high frequencies that could be harmful to us if they were low enough to hear. But nobody holds a candle to the sperm whale, whose clicks and calls have been measured as high as 230 decibels. That number drops significantly if the sound is traveling through air, but at 170 decibels, it’s still ear-shattering.
Scientists had thought for a long time that sperm whales were silent, but whalers had long told stories of what sounded like knocking on ships’ hulls when sperm whales were present. Once scientists listened to sperm whales with an underwater receiver, they thought the “muffled, smashing noise” was coming from inside the ship at first, before realizing they were picking up the atypical sounds of sperm whales, which don’t have the song-like quality of other species.
These Morse code-like clicks, used by sperm whales to communicate with one another, form an elaborate language, including phrases of clicks called codas. Different groups of whales even have different dialects within their codas. In addition to their communicative clicks, sperm whales also send out waves of sound at multiple frequencies as a form of echolocation while hunting their favorite food: giant squid.
You’ll often see explosions compared to the force of a nuclear blast — but no blast was bigger than Tsar Bomba, aka Big Ivan, a Soviet thermonuclear bomb detonated as a test on a small island in the Arctic Ocean in 1961. It was at least 3,300 times more powerful than the United States bomb dropped on Hiroshima in 1945, although its potential capacity was twice that. The flash was seen more than 600 miles away, and monitors as far away as New Zealand recorded three rounds of pressure waves.
As for the sound itself: A cameraman recording the event described it as “a remote, indistinct and heavy blow, as if the Earth has been killed.” The blast is typically referred to in terms of its force rather than its decibel level, but 224 decibels is a common estimate.
It’s no secret that rocket launches are really, really loud, but the Saturn V rocket, launched in the 1960s and 1970s during the Apollo program, was notoriously noisy. In testing, it measured as high as 204 decibels, although NASA notes that it typically maxed out at 195 — still plenty noisy enough to be dangerous.
Legends have circulated about this noise, some of them myths. It didn’t melt the concrete underneath it or start grass fires a mile away. Still, launch viewers had to stand around 3.5 miles away from the pad for their own safety.
NASA’s new Space Launch System (SLS) rockets will be even louder and more powerful, but the launch pads will have built-in sound dampening capabilities, using around 450,000 gallons of water that will rush onto the pad at launch to protect both eardrums and the equipment itself.
Asteroid impacts, like the 2013 Chelyabinsk Event, have created some of Earth’s biggest sounds, but the 1908 Tunguska Event in Siberia is perhaps the most legendary. Scientists believe that a space rock around 120 feet in diameter entered Earth’s atmosphere at about 33,500 miles per hour. After the resulting heat and pressure destroyed the rock itself, it became a fireball, releasing a destructive level of energy with no impact crater. Researchers were able to track ground zero from the pattern of the trees in the decimated forest around it; they fanned out radially away from the crash site until the very center, where trees stood upright, but entirely stripped of bark and branches.
One witness describes the impact’s sound as “a mighty crash… followed by a noise like stones falling from the sky, or of guns firing.” He had been working at a trading post 40 miles from the impact, and had been knocked out of his chair by a heat blast that made him feel as if his shirt was on fire. Later, scientists would estimate the sound of the blast at around 197 decibels.
Sarah Anne Lloyd
Writer
Sarah Anne Lloyd is a freelance writer whose work covers a bit of everything, including politics, design, the environment, and yoga. Her work has appeared in Curbed, the Seattle Times, the Stranger, the Verge, and others.
Advertisement
top picks from the optimism network
Interesting Facts is part of Optimism, which publishes content that uplifts, informs, and inspires.
The human body holds a host of extremes. The smallest muscles and bones stretch only a few millimeters, while other structures could wind around the Earth twice. Some organs in the body are completely vestigial, their use rendered obsolete by evolution, while others are largely responsible for what makes us human. These six facts explore those biological extremes, and illuminate the importance of the tiniest bones as well as the most vital organs.
The Smallest Muscle Stabilizes the Body’s Smallest Bone
The smallest muscle and the smallest bone in the human body form a convenient pair. The inner ear is home to the body’s three smallest bones, known collectively as the ossicles. Taken together, these bones are about the size of an orange seed, but the stapes is the smallest of them all. The stapes, which means “stirrup” in Latin (a reference to its shape), is essential to human hearing. Sound initially vibrates the tympanic membrane, otherwise known as the eardrum, and then travels through the ossicles. The stapes is the last bone in this chain, and causes a wave of fluid to generate in the inner ear that begins a process of converting sound waves into electrical signals that can be read by the brain. This incredibly tiny bone is supported by an equally tiny muscle called the stapedius. At less than 2 millimeters long, the stapedius is the smallest muscle in the human body.
There are some surprising lengths packed inside the human body. There’s the small intestine, for example, which could stretch 22 feet end to end (though hopefully it never has to). Not to be outdone, our nerves could stretch 37 miles if laid end to end. However, none of this compares to our circulatory system. According to the British Heart Foundation, the veins in an adult human could stretch an astonishing 60,000 miles — that’s farther than it takes to circumnavigate the globe twice. Capillaries, which transport blood between arteries and veins, make up 80% of this length.
Even Ancient Greeks Knew About the Body’s Smallest Organ
The smallest organ in the human body is located in a place you’d never think to look — the brain. The pineal gland, named after its pinecone-like appearance, is in charge of regulating our circadian rhythm by secreting melatonin. The Greek physician Galen originally named the pineal gland in the second century CE, and believed it regulated the flow of “psychic pneuma.” Descartes elaborated on the pineal gland’s function in the early 17th century, believing it was the point of contact where the soul met the body and was primarily where thoughts were formed. The gland’s true powers weren’t discovered until 1958.
The Heel Hosts the Most Variety of Fungus of Any Body Part
Not every bodily superlative is a happy one. In 2013, scientists analyzed the human body to discern what nook or crevice played host to the greatest variety of microscopic fungi. After conducting close inspections of palms, feet, toenails, groins, nostrils, and more, the researchers determined that the human heel is the body part most ripe with fungi. The heel of the foot contains 80 different types of fungi, and that number only increases when you include the rest of the foot, as toenails were found to provide refuge for 60 types of fungi (the space between toes adds another 40). While not all fungi are necessarily harmful, about half of them can be, and these numbers may help explain why feet are prone to fungal infection such as athlete’s foot.
There are 206 bones in the average adult human body, and our hands take up the lion’s share. Each hand is home to 27 bones, along with 34 muscles and 123 ligaments. Some experts estimate that a quarter of the motor cortex, the part of the brain responsible for voluntary movement, is devoted to the manipulation of our hands alone.
Although hands are impressive structures, they only just beat our feet by one measly bone. Because Homo sapiens’ primate ancestors walked on all fours, human hands and feet developed in similar ways. In fact, almost every bone in the palm is arranged in a pattern similar to the metatarsals in the foot. The only exception is a bone located at the edge of the wrist called the pisiform, which attaches various ligaments and tendons.
The Largest Lobe in the Brain Is What Makes Us Human
The frontal lobe is the largest lobe in the human brain, with studies placing its size between 25% to 40% of the cerebral cortex. Although all parts of the human brain work together, the frontal lobe is the region most associated with distinctively human characteristics such as language, creativity, and abstract thought. That’s why common systems of illnesses or injuries affecting the frontal lobe can affect someone’s personality, behavior, and in some cases, memory.
A famous medical case representing early investigations into the importance of the frontal lobe happened when a 19th-century railroad worker named Phineas Gage was severely injured after a premature explosion drove an iron bar through his skull. Though he survived the experience, Gage’s personality was irreparably altered to an almost childlike state, and his friends and family declared he was “no longer Gage.” His condition upended long-standing theories regarding the relation of the human mind and the brain, and today the case remains one of the greatest medical curiosities in history.
Interesting Facts
Editorial
Interesting Facts writers have been seen in Popular Mechanics, Mental Floss, A+E Networks, and more. They’re fascinated by history, science, food, culture, and the world around them.
Advertisement
top picks from the optimism network
Interesting Facts is part of Optimism, which publishes content that uplifts, informs, and inspires.
Is your stove keeping secrets from you? It’s quite possible. Manufacturers of modern appliances have packed their products with new and useful “hidden” features that may not be apparent unless you pore through the entire manual. Here are some secret hacks you may not know about your everyday appliances.
If you throw everything but the kitchen sink into your dishwasher, you may appreciate this. Many dishwashers now come with dedicated bottle jets that make cleaning bottles with long narrow necks an absolute breeze. (This feature is especially beloved by homebrewers who bottle their own beers.)
Curious children and appliances are a bad mix. As of March 2023, UL (formerly known as Underwriters Laboratories, which certifies products as safe) has a new standard that requires microwaves to have “a two-step process for opening microwave doors to help mitigate the risk of children being burned or scalded by cooked food.” (UL standards aren’t legally required, but manufacturers who want their certification must comply.) Some regular (i.e., nonmicrowave) ovens also have lock settings.
From sundown on Friday until sundown on Saturday, observant Jews are prohibited from doing any “work” on the holy day of rest (Shabbat). Manipulating electricity (by, say, switching a light off or on) is defined as work. Enter, appliances that can be set to “Sabbath mode.” In this setting, refrigerator lights will not come on when the door is opened, water and ice dispensers are disabled, ovens remain at a constant temperature, appliances do not beep or display temperature, and elevators stop at every floor.
Many (but not all) modern front-loading dryers and some washing machines offer flexibility and convenience by having reversible doors. If your laundry room setup doesn’t work with your current appliances and you’d like to reverse the direction the door opens, simply consult your manual and move the hinges to the other side.
Cleaning an oven is enough of a pain without contorting yourself around the oven door. Fortunately, most ovens and ranges have doors that are designed to lift off easily for better access, so you can clean and make minor repairs without awkward bending. Look for the latches attached to the hinges at the bottom of your door, disengage them, close the door about three-quarters of the way, and then simply lift up and out!
Many modern electric and induction cooktops now boast “melt and hold” functions. Melt allows for slow, gentle warming of things like chocolate, bringing them slowly to the desired temperature without the fuss of a double boiler or constant stirring. The “keep warm” function — often a small, separate burner toward the back of the cooktop — then keeps things nice and toasty … perfect for nacho cheese sauce while watching the big game.
Everyday spills and build-up disappear quickly and easily when using the steam clean feature on your oven. Operating at a lower temperature and for less time than a regular self-cleaning cycle, this function simply requires putting a cup or so of water in the bottom of a cold oven, selecting the setting, and then walking away. An hour or so later, oven grime is loosened, softened, and ready for wiping easily away.
Interesting Facts
Editorial
Interesting Facts writers have been seen in Popular Mechanics, Mental Floss, A+E Networks, and more. They’re fascinated by history, science, food, culture, and the world around them.
Advertisement
top picks from the optimism network
Interesting Facts is part of Optimism, which publishes content that uplifts, informs, and inspires.
Enter your email to receive facts so astonishing you’ll have a hard time believing they’re true. They are. Each email is packed with fascinating information that will prove it.
Sorry, your email address is not valid. Please try again.
Sorry, your email address is not valid. Please try again.
