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  • Near the turn of this century, scientist Georg Steinhauser had a problem.

  • He was fascinated by the question: Why do some belly buttons collect more lint than others?

  • But no one knew the answer.

  • So for three years he collected his own belly-button lint to find out.

  • And after interviewing friends and analyzing 503 of his own samples, Steinhauser discovered the culprit: stomach hair.

  • It scratches off tiny T-shirt fibers and directs them towards the belly button.

  • So that might be one mystery solved, but lint isn't the only thing inside these bizarre human crevices.

  • Your belly button is a scar, your very first one.

  • It forms when a doctor snips your umbilical cord, and, depending on how it heals, you could have an outie or, more likely, an innie.

  • And innies are ripe for colonization, not only by lint, hair, and dead skin cells, but also by bacteria.

  • In one study, 60 volunteers swabbed their belly buttons.

  • Researchers then analyzed the samples and found more than 2,300 kinds of bacteria.

  • That's an average of 67 different kinds per belly button.

  • Now, many of those microbes aren't unique to belly buttons, like staphylococcus, which can lead to staph infections.

  • It shows up in noses, throats, hair, and, yes, even belly buttons.

  • But the researchers also discovered other bacteria never before seen on human skin, like marimonas, which scientists had previously only seen in the ocean.

  • And they even found bacteria that chefs use to make cheese, and, yes, somebody did exactly that.

  • She grew the belly-button bacteria in a petri dish and then added it to milk.

  • Sure enough, after a few hours, the milk curdled into cheese.

  • Belly-button Brie, anyone?

  • Now, for the most part, the microbes in your navel are harmless.

  • In fact, recent studies suggest that bacteria on your body may strengthen your skin's defense system.

  • But if you never clean your belly button, they'll grow unencumbered, and that can be a problem.

  • The best-case scenario is that your belly button will start to smell.

  • When common navel microbes, like corynebacterium, build up, they emit pungent odors, similar to body odor.

  • But the worst case is that your navel will get infected, not just by staph but also by microbes that cause strep throat and yeast infections.

  • That's right, you can get a yeast infection in your belly button, which can lead to itching and redness, and cause a clear or off-white discharge to leak out, which almost looks like cottage cheese.

  • So how does that cheese sound now?

  • While microbes colonize your belly button from the outside, there could also be an invader from the inside.

  • We're talking about belly-button hernias.

  • In the womb, the umbilical cord runs from your mom to you, passing through an opening in your abdominal muscles.

  • Normally that opening seals up after you're born, but, in some cases, it never really closes all the way.

  • This can allow internal organs to slip through, creating a bulge behind your belly button.

  • Navel hernias affect as many as one in five newborns in the US, but they're rarely life-threatening, and are far less common in adults.

  • In fact, as long as you rinse your belly button with warm, soapy water once a week, the worst you'll have to put up with is a little fluff.

Near the turn of this century, scientist Georg Steinhauser had a problem.

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