10 Things About Your Belly Button That You’ve Probably Never Thought About Before
When was the last time you gazed at your navel? The belly button deserves more attention thanks to all the secrets it’s hiding.
Your delivery has nothing to do with your belly button
You’re getting a belly button regardless of how your birth goes, and the idea that your delivery room doctor has any influence over this is just one of the many myths surrounding pregnancy and birth. The belly button marks the area where your umbilical cord used to be attached, says Christopher S. Baird, PhD, a physics researcher, instructor, and adjunct professor at the West Texas A&M University.
When you’re in the womb, your umbilical cord attaches to your navel at one end and your placenta—a mass of blood vessels attached to the wall of your mother’s uterus—at the other. Your mother’s food and oxygen goes through her blood to the uterus where they are exchanged to your blood, which carries the nutrients from the placenta, down the umbilical cord, through your navel, and finally into your body.
Once you are born, the umbilical cord becomes useless now that your mouth, lungs, and digestive tract are functioning. The body responds to the transition by closing up the point where the umbilical cord connected to your body and created a belly button.
To free the body of the useless umbilical cord, your doctor cuts it down to a mere stub that hangs off your stomach. Within a few days to weeks, the stub will fall off as a result of the belly button naturally closing. Check out the surprising purposes of eight strange body parts.
Not all mammals have a belly button
Every human gets one, and each is distinctive—with twins, the belly button might be the easiest way to tell them apart. By the time you’re born, the belly button’s job receiving oxygen and nutrients through the umbilical cord is finished.
You would expect all mammals to have a belly button, but there are a couple of exceptions: Marsupials (like kangaroos and opossums) and the two egg-laying mammals (platypus and echidna). With the egg-layers, it makes sense that they could skip this valuable port into the digestive system. But how do marsupials get away with it? The fetus is incubated for much less time—about four to five weeks, so their need for in utero nutrition is less. After birth, they crawl up to mom’s pouch and latch on to a nipple, and do the rest of their fetal development there. Yes, your dog or cat has one—you just may not have noticed them because they’re usually smooth or flat and covered by fur.
Most start as outies
While most belly buttons begin as outies, the majority pop in to form innies, with only 10 percent of people holding onto their outies through adulthood. The reasons reinforce the idea that a doctor has little to do with the end result.
“The difference between an ‘innie’ and an ‘outie’ belly button has nothing to do with management of the umbilical cord at birth,” reports Trey Eubanks, MD, chief of Surgery and medical director of Trauma Services for Le Bonheur Children’s Hospital in an article for the hospital. This reinforces the lack of a doctor’s role in your belly button. “Most people who have an ‘outie’ fall into one of two categories: Either they were born with a tiny umbilical hernia, which is most likely, or had a small infection at the base of the umbilical cord that went unnoticed. This will cause unusual tissue called granulation tissue to form. Later in life, this looks like a knot or polyp of skin protruding from the base of the umbilicus.”
While there is a 90 percent chance that any child born with an outie will eventually have an innie by the time they are five years old, the chances of it switching are slim to none after this age. Here are some strange facts about the the things you’ve always wondered about your body.
It’s teeming with bacteria
Despite its proximity to you, the belly button goes largely ignored, unless you adorn it with body jewelry or are fond of midriffs. But it’s actually one of several body parts that accumulates weird gunk. According to a 2011 study conducted by scientists from the biology department of North Carolina State University, and the Nature Research Center at the North Carolina Museum of Natural Sciences, the belly button has 2,368 bacterial species, 1,458 of which may be new to science. The researchers even found that one person’s belly button had bacterium previously found only in soil from Japan, though the man had never been there before.
Belly button plastic surgery is a big deal
Not everyone is keen on their belly button, which is why belly button plastic surgery is kind of a big deal: About 2,000 people undergo it annually. The elective surgery is called umbilicoplasty and, according to Richard Chaffoo, MD, president of the San Diego Plastic Surgery Society and chief of plastic surgery at Scripps Memorial Hospital, in Encinitas, California, the popularity of showing off tummies has caused a massive uptick in the number of requests for it. Most people have the surgery to change their outie into an innie.
“What I often see is a patient comes in with an outie and it’s actually a small umbilical hernia,” explains Scot Glasberg, MD, a plastic surgeon in private practice in New York City and past president of the American Society of Plastic Surgeons. “You go in and fix the hernia and then you tack it down to the tissues underneath to try to make it an innie. That’s the most common scenario,” he said. Make sure you know the scientific explanations behind 20 quirky body reactions.
Despite the growing Western trend of belly button exposure, it hasn’t always been that way, and, in some cultures, it’s still considered taboo.
In Western culture, the belly button was considered indecent until recently. In 1951, the National Association of Broadcasters created its Code of Practices for Television Broadcasters, which prohibited the exposure of a woman’s navel, along with a lot of other things. (It’s true: With few exceptions, I Dream of Jeannie was remarkably navel-free.) The Code was upheld, astonishingly, until 1983.
However, it is has long been acceptable and celebrated for women in Indian culture, while in northern Japan, during the Jomon period, the belly button was often exaggerated in art, symbolizing the center where life begins.
Some are considered more attractive than others
The science of attraction is real, and it extends to navel-gazing. According to University of Helsinki researcher Aki Sinkkonen, people prefer navels that are T-shaped or oval, and vertical with a little hooding. While outies are considered unattractive, it may come of surprise that innies that are too deep are also given the cold shoulder.
Sinkkonen also says that a woman’s navel is indicative of her reproductive potential as well. In the study, he proposes that “the symmetry, shape, and position of umbilicus can be used to estimate the reproductive potential of fertile females, including risks of certain genetically and maternally inherited fetal anomalies.” These are the biggest unsolved mysteries about the human body.
Belly button lint is pretty gross
Bokeh Blur Background/Shutterstock
Certainly not the most enjoyable part of the belly button, lint is made up of stray fibers from clothing, along with dead skin cells and body hair. According to University of Sydney researcher Karl Kruszelnicki, navel lint is more often found in middle-aged, overweight men with a hairy abdomen than anyone else.
According to the findings of both an online survey as well as collected samples from willing volunteers, lint buildup is generated in part by the friction of belly hair on clothing fibers. For his work, Kruszelnicki received an Ig Nobel Prize in 2002, which is an award given for research that “first makes you laugh, and then makes you think.”
Want to avoid lots of lint? Try wearing older shirts, as they shed less. Check out these other explanations for gross substances on your body.
Pregnancy changes innies to outies
While people born with outies can experience a shift to an innie early in childhood, there’s one instance where the general rule of thumb goes the opposite direction. The expanding abdomen of pregnancy can pop some innie belly buttons out. (This does not necessarily indicate the baby is done.) The structure goes relatively unchanged, however and, after delivery, mothers can expect their belly button to return to its typical shape.
The belly button is an erogenous zone
Media has done a great job of hyping up this body part as sexually explicit, but the navel’s heightened sensitivity may also attribute to its status as sensual.
“Simply viewing the belly button area can be a sexual trigger, psychologist Leon F. Seltzer, PhD, writes in Psychology Today. “From heterosexual man’s point of view, seeing the exposed navel and surrounding area can be very attractive. It accentuates a woman’s waistline, her curves and brings out the beauty and fertility of a woman’s body.”
Based on touch, he notes that the navel and genitals have a common tissue origin that accounts for similar sensations. Here are 20 obscure facts you never knew about your own body.