12 Facts About Belly Buttons

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Belly buttons are many things bundled up into one tiny knot: Collectors of lint. Harborers of bacteria. Objects of desire. Symbols of creation and birth. From the gross to the sexy to the spiritual, there’s a lot to unpack about the belly button’s place in history, culture, science, and religion. Let's get started.

1. THEY'RE REALLY JUST SCARS.

That little spot in the center of your belly marks the place where your umbilical cord once connected you to your mom’s placenta. When that cord is cut, a little, shriveled piece of it gets left behind. It eventually falls off—usually within the first week of a baby’s life—and what remains is a scar. Of course, “belly button” sounds a lot cuter than “belly scar.”

2. DOCTORS CAN’T CHOOSE A BABY'S BELLY BUTTON SHAPE …

Whether your belly button caves in or sticks out has nothing to do with how your doctor cut or clamped your umbilical cord. It all comes down to the amount of space between the skin and the abdominal wall, which determines how much skin—and scar tissue—is left behind. "You can't do anything to make sure babies have an innie or outie," Dr. Dan Polk, a neonatologist at Children's Memorial Hospital in Chicago, told the Chicago Tribune. "It has to do with how much baby skin leads onto the umbilical cord from the baby's body. Less skin makes an innie; more skin makes an outie." About 90 percent of people have innies, and the rest are outies. In some cases, an outie orientation is the result of an umbilical hernia, which occurs when part of the intestine pokes through the umbilical opening in the abdominal wall. It usually seals up naturally by the time a child reaches the age of 2, but more persistent cases may require surgery.

3. … BUT A COSMETIC SURGEON CAN TURN AN OUTIE INTO AN INNIE.

For those who don't like their outie, cosmetic surgery is an option—albeit a drastic one. Umbilicoplasty is a surgery that alters the size or shape of the belly button, often by removing excess skin or tightening abdominal skin. A 1971 article in the Honolulu Star-Bulletin called belly button beautification the “newest gimmick in the cosmetic surgery game.” The article cited a Japanese physician who had performed more than 3000 navel operations in the ‘60s and early ‘70s for about $80 to $150 a pop. (Now, the surgery costs about $2000 in the U.S.)

An article in The Ottawa Citizen suggested that the surgical technique dates back to the early 1900s, when it was usually done as a corrective measure in conjunction with tummy tuck surgeries, which often displace the belly button. Even if there’s no medical need, a patient can now opt for umbilicoplasty to get the “ideal” shape. “What was favored through the Greek, Roman, and Western civilization to our time is an oval belly button that is more or less vertically oriented,” New York City cosmetic surgeon Bruce Nadler told the paper in 2002, when these surgeries were starting to become more popular. By contrast, Nadler said, horizontal belly buttons are considered more desirable in Asian cultures because they’re associated with good fortune.

4. MOST MAMMALS HAVE ONE.

Dogs, chimpanzees, lions, and armadillos have one, but their navels aren’t always easy to spot. For one, most mammalian mothers chew off the umbilical cord attached to their newborns, leaving a flat scar that’s harder to detect than a human belly button. Gorillas and chimpanzees are an interesting case for navel-gazers because they have what some scientists call an “in-betweeny”—a navel that looks like a human’s but is neither an innie nor an outie.

However, there are a few notable exceptions to the mammal belly button rule. Platypuses, which lay eggs, have no umbilical cord and therefore no belly button. As for marsupials like kangaroos and koalas, their umbilical cords generally fall off while they’re still inside mom's pouch, so a scar never forms.

5. THE FEAR OF BELLY BUTTONS IS CALLED OMPHALOPHOBIA.

Some people feel anxious, afraid, or disgusted when their belly button is touched or when someone else's bare midriff is on display. This is called omphalophobia, which stems from the Greek word omphalo for navel. This fear is believed to be linked to the navel's association with umbilical cords and wombs, or perhaps the irrational childhood fear that a belly button will come undone, letting one’s guts spill out. The phobia has gained more national exposure ever since TV personality Khloé Kardashian admitted she has a fear of belly buttons.

6. IF YOU POKE IT, YOU MIGHT SUDDENLY GET THE URGE TO PEE.

Speaking of touching your belly button (and all the grossness that comes with it), you may feel a tingly sensation when you stick your finger in it. That’s because you're stimulating fibers lining the inside of your abdomen, which then send a message to your spinal cord. As Dr. Christopher Hollingsworth of NYC Surgical Associates explained to BuzzFeed, “Because your spinal cord at that level is also relaying signals from your bladder and urethra, it feels almost the same. You interpret this as discomfort in your bladder."

7. THEY CAN LEAK URINE.

In a similar vein, a rare abnormality can cause urine to leak out of the belly button. In the early stages of pregnancy, a tube called the urachus connects a fetus’s bladder and belly button and allows urine to drain. It usually atrophies and turns into a scar on the bladder at birth or soon after, but not always. Some people may never know they still have all or part of their urachus attached because it only becomes a problem if the tube doesn’t close up. In those cases, urine can travel up through the urachus and leak out of the umbilicus (navel). Surgery is generally needed to fix this issue.

8. THEY GROW SPECIAL FLUFF-CATCHING HAIRS.

Have you ever wondered why bits of lint keep collecting in your belly button, despite your best efforts to keep clean? Blame it on a special type of hair that grows in navels. These hairs have tiny barbs that protrude and rub against your clothing, causing small fibers to scrape off. The hairs are arranged in concentric circles, which act as a funnel and suck fluff into your navel. Those who shave their stomachs or don't grow a lot of body hair to begin with likely don't have many problems with lint.

9. THEY CONTAIN THOUSANDS OF KINDS OF BACTERIA.

Beyond lint, a lot of dead skin, discarded fat molecules, and thousands of bacteria also live in your navel. One 2012 study led by the aptly named Belly Button Biodiversity project documented 2368 types of bacteria in the navels of 66 study participants. Fret not, though: They help to protect you against harmful pathogens. “We know that without these microbes our immune systems won’t function properly,” the head of the project, Dr. Rob Dunn, said in a statement. “In fact, this collection of microbes must have a certain composition—must form a certain microbial ecosystem—in order for our immune system to function properly."

10. THEY USED TO BE BANNED ON TV.

In Western culture, belly buttons have been regarded as "a feminine sexual center since ancient times," according to the Online Etymology Dictionary. As such, they were deemed too lewd to show on television, according to the Code of Practices for Television Broadcasters, established by the National Association of Broadcasters in 1951. Barbara Eden, who played the titular role in I Dream of Jeannie, said network executives at NBC held meetings over whether to let her flash her navel during the show’s run in the ‘60s. Her producer, George Schlatter, “said he had never seen so many suits sitting around a table in his life discussing someone's anatomy,” Eden told the TODAY show. Although Eden’s genie get-up never ended up revealing her belly button, other shows started to push the envelope around the same time. The belly-button ban technically remained in effect until 1983, but it wasn’t exactly enforced. Yvette Mimieux of Dr. Kildare became the first actress to bare her navel on television in 1964, and others followed suit soon after.

11. THEY ARE THE SOURCE OF A LONGSTANDING THEOLOGICAL DEBATE.

Among Christians, the debate over whether Adam and Eve had belly buttons is a little like the age-old “chicken or egg” question. One popular argument holds that Adam and Eve weren’t born naturally from a mother, and thus they wouldn’t have had umbilical cords or belly buttons. Others disagree for various reasons and insist that navels have been around since the dawn of time. Both Raphael and Michelangelo depicted Adam and Eve with navels in their artwork (including the Sistine Chapel's ceiling painting), leading one 17th-century doctor and philosopher to decry these “vulgar errors,” according to the book Umbilicus and Umbilical Cord by Mohamed Fahmy. Other artists tried to avoid the issue altogether by concealing the couple’s abdomens with foliage, forearms, or long hair.

A few centuries later, a U.S. House of Representatives subcommittee refused to distribute a booklet called Races of Man to World War II soldiers because it contained pictures of Adam and Eve with navels. Members of the committee ruled that this image “would be misleading to gullible American soldiers.”

12. THEY ARE CELEBRATED IN SOME CULTURES.

Think of Middle Eastern belly dancing and midriff-baring Indian attire. In some places around the world, the navel holds cultural and even spiritual significance. Some Hindus believe that a lotus emerged from the god Vishnu’s navel, and at the center of the flower was Brahma—the creator of the universe. Likewise, in Japan, the belly button may represent the point where life begins. In the Middle Jōmon period (2500-1500 BCE), Japanese artists emphasized the appearance of navels on their human-like figurines. Today, a belly button festival is held annually in the town of Shibukawa in central Japan. “The belly button is traditionally believed to be located in the middle of the body and the most important part,” festival organizer Kazuo Yamada told Reuters. “Our town, Shibukawa, is also called the belly button of Japan, and that is how this festival began.”

12 Facts About the Sense of Taste

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A lot more than your tongue is involved in the process of tasting food. Taste is not only one of the most pleasurable of the five senses, but a surprisingly complex sense that science is beginning to understand—and manipulate. Here are 12 fascinating facts about your ability to taste.

1. Everyone has a different number of taste buds.

We all have several thousand taste buds in our mouths, but the number varies from person to person. The average range is between 2000 and 10,000. And taste buds are not limited to your tongue; They can be found in the roof and walls of your mouth, throat, and esophagus. As you age, your taste buds become less sensitive, which experts believe may be why foods that you don’t like as a child become palatable to you as an adult.

2. You taste with your brain.

The moment you bite into a slice of pie, your mouth seems full of flavor. But most of that taste sensation is happening in your brain. More accurately, cranial nerves and taste bud receptors in your mouth send molecules of your food to olfactory nerve endings in the roof of your nose. The molecules bind to these nerve endings, which then signal the olfactory bulb to send smell messages directly to two important cranial nerves, the facial nerve and the glossopharyngeal nerve, which communicate with a part of the brain known as the gustatory cortex.

As taste and nerve messages move further through the brain, they join up with smell messages to give the sensation of flavor, which feels as if it comes from the mouth.

3. You can’t taste well if you can’t smell.

When you smell something through your nostrils, the brain registers these sensations as coming from the nose, while smells perceived through the back of the throat activate parts of the brain associated with signals from the mouth. Since much of taste is odor traveling to olfactory receptors in your brain, it makes sense that you won’t taste much at all if you can’t smell. If you are unable to smell for reasons that include head colds, smoking cigarettes, side effects of medications, or a broken nose, olfactory receptors may either be too damaged, blocked, or inflamed to send their signals on up to your brain.

4. Eating sweet foods helps form a memory of a meal.

Eating sweet foods causes your brain to remember the meal, according to a 2015 study in the journal Hippocampus, and researchers believe it can actually help you control eating behavior. Neurons in the dorsal hippocampus, the part of the brain central to episodic memory, are activated when you eat sweets. Episodic memory is that kind that helps you recall what you experienced at a particular time and place. "We think that episodic memory can be used to control eating behavior," said study co-author Marise Parent, of the Neuroscience Institute at Georgia State. "We make decisions like 'I probably won't eat now. I had a big breakfast.' We make decisions based on our memory of what and when we ate."

5. Scientists can turn tastes on and off by manipulating brain cells.

Dedicated taste receptors in the brain have been found for each of the five basic tastes: sweet, sour, salty, bitter, and umami (savory). In 2015, scientists outlined in the journal Nature how they were able to turn specific tastes on or off in mice, without introducing food, by stimulating and silencing neurons in the brains. For instance, when they stimulated neurons associated with “bitter,” mice made puckering expressions, and could still taste sweet, and vice versa.

6. You can tweak your taste buds.

Most of us have had the experience of drinking perfectly good orange juice after brushing our teeth, only to have it taste more like unsweetened lemon juice. Taste buds, it turns out, are sensitive enough that certain compounds in foods and medicines can alter our ability to perceive one of the five common tastes. The foaming agent sodium lauryl/laureth sulfate in most toothpaste seems to temporarily suppress sweetness receptors. This isn't so unusual. A compound called cynarin in artichokes temporarily blocks your sweet receptors. Then, when you drink water, the cynarin is washed away, making your sweet receptors “wake up” so the water tastes sweet. A compound called miraculin, found in the herb Gymnema sylvestre, toys with your sweet receptors in a similar way.

7. The smell of ham can make your food “taste” saltier.

There’s an entire industry that concocts the tastes of the food you buy at the grocery store. Working with phenomena known as phantom aromas or aroma-taste interactions, scientists found that people associate “ham” with salt. So simply adding a subtle ham-like scent or flavor to a food can make your brain perceive it as saltier than it actually is. The same concept applies to the scent of vanilla, which people perceive as sweet.

8. Your taste buds prefer savory when you fly.

A study by Cornell University food scientists found that loud, noisy environments, such as when you’re traveling on an airplane, compromise your sense of taste. The study found that people traveling on airplanes had suppressed sweet receptors and enhanced umami receptors. The German airline Lufthansa confirmed that on flights, passengers ordered nearly as much tomato juice as beer. The study opens the door to new questions about how taste is influenced by more than our own internal circuitry, including our interactions with our environments.

9. Picky eaters may be “supertasters.”

If you’re a picky eater, you may have a new excuse for your extreme dislike of eggplant or sensitivity to the slightest hint of onion. You might be a supertaster—one of 25 percent of people who have extra papillae in your tongue. That means you have a greater number of taste buds, and thus more specific taste receptors.

10. Some of your taste preferences are genetic.

While genetics may not fully explain your love of the KFC Double Down or lobster ice cream, there may be code written into your DNA that accounts for your preference for sweet foods or your aversion to certain flavors. The first discovery of a genetic underpinning to taste came in 1931, when chemist Arthur Fox was working with powdered PTC (phenylthiocarbamide), and some of the compound blew into the air. One colleague found it to have a bitter taste, while Fox did not perceive that. They conducted an experiment among friends and family and found wide variation in how (and whether) people perceived the flavor of the PTC to be bitter or tasteless. Geneticists later discovered that the perception of PTC flavor (similar to naturally occurring compounds) is based in a single gene, TAS2R38, that codes for a taste receptor on the tongue. In a 2005 study, researchers at the Monell Chemical Senses Center found that the version of this gene also predicted a child's preference for sweet foods.

11. Your genes influence whether you think cilantro tastes like soap.

There may be no flavor more hotly debated or deeply loathed than the herb cilantro (also known as coriander). Entire websites, like IHateCilantro.com, complain about its “soapy” or “perfumy” flavor, while those who like it simply think it gives a nice kick to their salsa. Researchers at the consumer genetics company 23andMe identified two common genetic variants linked to people's “soap” perceptions. A follow-up study in a separate subset of customers confirmed the associations. The most compelling variant can be found within a cluster of olfactory receptor genes, which influence our sense of smell. One of those genes, OR6A2, encodes a receptor that is highly sensitive to aldehyde chemicals, which cilantro contains.

12. Sugar cravings have a biological basis.

Your urge for more hot fudge may have little to do with a lack of self-control. Scientists think that our yearning for sweets is a biological preference that may have been designed to ensure our survival. The liking for sweet tastes in our ancient evolution may have ensured the acceptance of sweet-tasting foods, such as breast milk and vitamin-rich fruits. Moreover, recent research suggests that we crave sweets for their pain-reducing properties.

12 Facts About the Pancreas

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You could live without your pancreas, but it wouldn’t be easy. For one, you would need to give yourself insulin shots on a daily basis because you would develop diabetes. A helping of enzyme pills would also be needed to help you digest food. It's clear that the 6-inch-long pancreas, located behind your stomach, has crucial functions—and that's why diseases like pancreatic cancer and pancreatitis are often so devastating. Here are a few other important facts to know about the pancreas.

1. Pancreas means “all flesh” in Greek.

Around 300 BCE, a surgeon in ancient Greece named Herophilus became the first person to formally describe the pancreas as a gland. However, the organ didn’t get its name until about 400 years later, when another Greek surgeon and anatomist named Ruphos dubbed it the pankreas, meaning “all flesh”—possibly because of its lack of bone or cartilage. (The plural of pancreas, by the way, is pancreata or pancreases.) Later, in the 16th century, people started referring to a dish of cooked calf or lamb pancreas as “sweetbreads.” That name possibly stems from bræd, the Old English word for “flesh.”

2. The pancreas has a head and a tail.

The pancreas has four main parts: the head, neck, body, and tail. The widest part is the head, which is attached to the first part of the small intestine, known as the duodenum. In cases where a pancreatic tumor is present, the head is usually the part that’s affected. However, according to one study from 2008, people with tumors in the body or tail of the pancreas had lower survival rates than those with cancer in the head of the pancreas.

3. The man who discovered the pancreatic duct may have been murdered for his work.

The pancreatic duct is a tiny tube that runs the length of the pancreas and carries digestive juices to the duodenum. Although the ancient Greeks knew about the pancreas, its function and anatomy weren’t fully understood for centuries. That started to change in 1642, when German anatomist Johann Georg Wirsung discovered the pancreatic duct after performing a dissection on a man who had been hanged for murder. He named it the “duct of Wirsung” after himself, which may have upset some people. Wirsung was murdered the following year, allegedly over a disagreement as to who had actually discovered the duct.

4. It functions as both an endocrine and exocrine gland.

Although food never enters the pancreas, the organ does play a key role in digestion. It produces pancreatic fluid, which gets piped through the pancreatic duct to the duodenum. Once it’s in the digestive tract, the enzymes in the fluid help break down fat, protein, and carbohydrates. By sending a substance through ducts to other parts of the body, it functions as an exocrine gland. At the same time, it also functions as an endocrine gland by secreting two hormones directly into the bloodstream to help control blood sugars. Insulin is released when you have too much sugar, and glucagon is released when you don’t have enough sugar.

5. The pancreas can “taste” sugar.

The pancreas has taste receptor cells that let it sense the presence of sugar. It can “taste” artificial sweeteners, too. However, unlike the taste buds on our tongue, it doesn’t relay these sensations back to the brain. Instead, this sensory information helps the pancreas balance out the hormones and maintain healthy glucose levels in the body.

6. Diabetes is the result of damage to pancreatic cells.

For reasons that remain a scientific mystery, people with type 1 diabetes have immune systems that attack the insulin-producing cells in their pancreas. This prevents the cells from making insulin, and without insulin, other cells can't access the glucose in the bloodstream for energy. Sugar then builds up unhealthily in the bloodstream. People with type 2 diabetes, on the other hand, can still produce some insulin, but it’s not enough. Their cells become resistant to insulin (often as a result of obesity), which causes glucose to accumulate in the bloodstream.

7. The pancreas can digest itself.

Pancreatitis refers to the inflammation of the pancreas, but more alarmingly, what’s actually happening is that the digestive enzymes in the gland are going rogue and “digesting the pancreas itself,” according to Medline Plus. Heavy alcohol consumption is the most common cause of the disease, but other causes may include gallstones, cystic fibrosis, or high levels of fats or calcium in the blood. Most people with acute pancreatitis end up in the hospital, and it often goes away in a couple of days. Chronic pancreatitis can result in more serious complications.

8. Scorpion stings can cause pancreatitis.

The venom of a Brazilian scorpion, Tityus serrulatus, can cause pancreatitis, according to researchers at North Carolina State University. One particular enzyme in the venom attacks certain proteins in the gland, which impairs the pancreatic cells' functions and leads to inflammation. In a separate study of a related species (T. stigmurus), researchers found that “acute pancreatitis due to scorpion is usually transient [and] self-limited ... but it could progress to hemorrhagic pancreatitis and lead to death.”

9. Ruth Bader Ginsburg beat the odds and survived pancreatic cancer.

Ten years after she recovered from colon cancer, Ruth Bader Ginsburg received bad news following a routine check-up in 2009: She had pancreatic cancer. Fortunately, surgeons were able to remove the tumor, and at 85 years old (and counting), Ginsburg is now the oldest Justice on the U.S. Supreme Court. However, most people with pancreatic cancer aren’t so lucky. Although it’s less prevalent than skin, breast, and prostate cancers, it’s one of the deadliest. Just 8 percent of pancreatic cancer patients in the U.S. live longer than five years, according to the American Cancer Society.

James Cleary, an oncologist at the Dana-Farber Cancer Institute in Boston, says it’s very hard to catch in the early stages. “The reason pancreatic cancer can be so difficult to catch is number one, it’s a fast-moving cancer and can grow very rapidly,” he tells Mental Floss. “And number two, it can grow in a spot where you don’t get any symptoms until it’s too late.” In some cases, the cancer may start in the pancreas and spread to the liver or lining of the abdomen without any symptoms showing up.

10. Pancreatic surgery is extremely difficult to pull off.

Sometimes, patients with pancreatic cancer will undergo a complicated surgery called a Whipple procedure, which involves the removal of the head of the pancreas, part of the small intestine, the gallbladder and bile duct, and sometimes part of the stomach, too. However, very few people with pancreatic cancer are candidates for surgery—even if the cancer hasn’t yet spread to neighboring organs. That’s because cancer cells sometimes surround important blood vessels, making it “a tricky area” to operate on, according to Cleary. “The pancreas plays a really important role in digestion, and because of that, it’s very close to several important blood vessels and it’s very close to the stomach and small intestine,” he says.

11. There are genetic components to pancreatic cancer.

More than 90 percent of pancreatic cancers involve a mutation of the KRAS gene, which is also responsible for about half of all human cancers, according to Cleary. However, a drug hasn’t been invented yet to turn this particular gene off. “Finding a way to make a drug successfully target KRAS is one of holy grails of oncology," Cleary says. "It is of such great importance to oncology that a Nobel Prize could be awarded to whoever figures out how to make effective KRAS targeted therapy."

Mutations of DNA repair genes occur in up to 20 percent of pancreatic cancer cases. Some of these mutated genes, like BRCA1 and BRCA2, can run in families. This is why some families have several members who end up suffering from pancreatic cancer. Jimmy Carter, for example, lost his father, brother, and two sisters to pancreatic cancer. His mother had breast cancer that migrated to her pancreas. PARP inhibitors (drugs that block a particular enzyme) have been used to target DNA repair genes in breast and ovarian cancers, and there is now hope that they may also be effective in treating pancreatic cancer.

12. An aggressive form of chemotherapy is helping pancreatic cancer patients live longer.

A chemotherapy regimen called FOLFIRINOX has made significant improvements in the care of pancreatic cancer patients ever since it was introduced in 2010 as a treatment for patients with metastatic disease. Before 2010, “It was very, very rare to see anyone with metastatic cancer living longer than one year,” Cleary says. With FOLFIRNOX, it's not uncommon to see patients with metastatic pancreatic cancer living two years. A huge step forward came in June 2018 when researchers from France found that giving FOLFIRINOX after surgery could increase survival by a median of 20 months longer compared to the standard chemotherapy. Now, researchers are conducting trials to see if FOLFIRINOX can effectively be administered before a patient undergoes surgery. Considering that most patients aren’t eligible for surgery at diagnosis, pre-operative FOLFIRINOX could shrink the pancreatic tumor and increase the number of patients that are able to safely receive surgery.

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