Buzz
You might not give it much thought, but there's a wealth of information about the human body. For example, did you know that humans have invisible stripes on their skin? In this article, adapted from an episode of The List Show, we explore some astonishing facts about the human body that you may not be aware of.
1. Only humans have chins.
Humans are the only creatures with chins. While it may seem like every animal has one, that’s simply a term we use for the bottom of the head. In reality, a chin is a unique bone structure that juts out from the lower jaw. Some researchers suggest that elephants and manatees might have chins, but others believe their structures are so different that they shouldn’t be compared to the human chin. Scientists are still uncertain about why humans developed chins; it could be related to eating or speaking, or they may have appeared as an unintended side effect of another evolutionary trait.
2. Humans possess a unique bone known as the hyoid.
A fascinating bone in the human body is the hyoid, which is the only bone that doesn’t connect to another bone. Instead, it’s attached to muscles and ligaments. The hyoid rests between the jaw and the voice box, playing a key role in keeping the muscles of the lower mouth in position. It also aids in swallowing and speaking.
3. People with more body hair and innie belly buttons are more likely to experience belly button lint.
Those with more body hair and an innie belly button are more prone to belly button lint, which is made up of fibers that rub off clothes over time. Stomach hair collects these fibers and draws them into the belly button.
In 2011, a team of scientists launched the Belly Button Biodiversity Project to explore the mysteries hidden in these small body crevices. The results were surprising—samples from around 60 individuals revealed over 2300 species of bacteria. Out of these, only eight were common, appearing in more than 70 percent of belly buttons.
4. Fingernails generally grow faster than toenails, though it varies between individuals.
Your fingernails tend to grow faster than your toenails. While this can differ from person to person, on average, fingernails grow about a tenth of a millimeter each day, while toenails grow at about half that rate. There’s a connection between the growth speed of nails and the length of the closest bone, meaning your longest fingers typically have nails that grow faster than those on your shorter fingers.
5. Fingernails grow quicker on your dominant hand.
The fingernails on your dominant hand grow faster. The reason for this remains unclear.
6. Your nails change as you age.
Specifically, they grow more slowly, and nail cells, called onychocytes, begin to build up. This is why older individuals tend to have thicker toenails. Fingernails don't show as many changes because people take better care of them, and our toes endure much more wear and tear over time.
7. It’s a myth that hair and nails continue to grow after death.
What actually occurs is that the skin dries out and shrinks. This creates the illusion that hair and nails are growing, but in reality, it's the skin that's retracting.
8. Breastfeeding does not cause breasts to sag.
A common myth is that breastfeeding leads to breasts sagging. While pregnancy can stretch and reshape breasts, research shows breastfeeding itself does not cause them to droop. However, smoking is a factor that can contribute to sagging.
9. Your hands and feet contain more than half of the bones in your adult body.
With about 27 bones in each hand—referred to as daddles, an old slang term—and approximately 26 bones in each foot—known as plates of meat, another old slang word—these body parts make up more than half of the 206 bones in the human body. However, this doesn’t always apply at birth, as feet mostly consist of cartilage that gradually transforms into bones, which don’t fully solidify until a person reaches their early twenties.
10. A sneeze can fracture a rib.
Though rare, it is possible to fracture a rib from sneezing. In 1885, the Journal of the American Medical Association published a report about a 72-year-old man who broke his eighth rib during a sneeze. Fun fact: the word sneezer, a 1940s Australian slang term, means “excellent, wonderful”—a description that might fit a great sneeze, but not one that causes a rib to break.
11. Rubbing your eyes can make you see stars.
If you've ever seen stars after rubbing your eyes, it's not just your imagination. The cells in your eyes interpret the pressure as though it were light, processing it in the same way.
12. Goosebumps serve little purpose today.
Goosebumps are often linked to the release of adrenaline in the body, usually during intense emotional moments. They were once useful when people had more body hair, as the raised hairs made them appear larger in threatening situations. Now, however, goosebumps are pretty much a redundant feature.
13. The spleen plays a role in the immune system.
Surprisingly, the spleen is not completely useless, despite being thought of as such until the 1950s. While it’s okay to have your spleen removed, it does help the immune system. While blood passes through the spleen, the immune system produces antibodies to fight any bacteria present. Additionally, a fetus’s spleen is responsible for creating red blood cells.
14. The appendix may play a role in supporting the immune system.
While it’s fine to have your appendix removed, this organ does contribute to the immune system. In 2018, Dr. Mohamad Abouzeid, assistant professor and attending surgeon at NYU Langone Health, told Mytour, "[The appendix] has a high concentration of immune cells within its walls." Though experts are still uncertain about its exact function, the appendix seems to help maintain overall health.
15. A fetus’s face begins to form within the first three months of conception.
In the first trimester, a fetus’s face starts taking shape, with the parts of the upper lip fusing together. This process creates the dent under the nose, known as the philtrum, which serves as a lasting reminder of a person’s early stages in the womb.
16. Babies don’t see the world in black and white.
A newborn baby’s vision isn’t great, but it’s a misconception that they can only see in black and white. In fact, they can detect the color red, but only when it appears against a gray background. At birth, their visual acuity is just 5 percent of an adult’s, but it improves rapidly, and by six months, their vision is nearly as good as that of an adult. Interestingly, babies excel in some types of visual tests, such as recognizing monkeys, which adults and older babies can’t do.
17. The liver has an incredible ability to regenerate itself.
Remarkably, the liver can regenerate with only 25 percent of its original tissue remaining. Liver transplants are generally required only after the organ has suffered severe damage or injury.
18. Some individuals are born with three kidneys.
In rare cases, a kidney splits while the person is still in the womb, resulting in a person being born with three kidneys. These individuals are prime candidates for organ donation, though many people don’t realize they have an extra kidney.
19. The large intestine of a person can stretch up to 5 feet, while the small intestine can extend to 20 feet.
Your intestines are remarkably long: The small intestine stretches to about 20 feet, while the large intestine reaches around 5 feet. The surface area of your intestines could cover the area of two tennis courts, though some Swedish researchers suggest it’s more like the size of a studio apartment. To put this into perspective, a blue whale has intestines that measure more than 700 feet.
20. The stomach has the capacity to hold between 16 to 50 fluid ounces.
Although not as large as a tennis court, the stomach can hold a substantial amount—up to 50 fluid ounces. Interestingly, a Trenta-sized drink at Starbucks holds 31 fluid ounces, which is more than many adult stomachs can manage.
21. Serotonin, a neurotransmitter, is found in the gut.
Our gut holds around 95 percent of the neurotransmitter serotonin. With its 100 million neurons, the gut is so crucial to mood regulation that it’s often referred to as the “second brain.” Medications targeting serotonin frequently cause gastrointestinal issues as a side effect.
22. The skin is the largest organ in the body.
The skin is not only an organ but also the largest one we have. An adult’s body may have up to 22 square feet of skin, which is about the size of half the floor of a typical bathroom.
23. Skin contributes significantly to your body weight.
Your skin accounts for 15 percent of your total body weight.
24. The ovaries are in communication with the brain.
It was once thought that the ovaries and uterus remained dormant until needed, but the ovaries actually communicate with the brain in ways that are still being discovered. The hypothalamus and ovaries work together to regulate hormone levels, such as estrogen and progesterone, ensuring they are in proper balance.
25. Humans are covered in stripes.
Humans have stripes across their bodies, known as Blaschko’s Lines, which are usually invisible. These lines are remnants from our early development, marking the journey from a single cell to a fully formed human being.
26. Humans glow, but our eyes aren't able to detect it.
Humans glow, though it's about 1000 times too faint for our eyes to detect. Every living creature that undergoes metabolic processes glows because these reactions release photons, which create light. A 2009 study used a camera to capture the bioluminescence of five men, revealing that our upper body emits the most light. This glow follows a cycle, being brightest around 4 p.m. when we're on a regular sleep schedule.
