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Belly Buttons Called the Rain Forest of the Human Body: You Won't Believe What Scientists Found in There


"...went boldy where few had dared or really wanted to go before"

Rob Dunn points out in his article that he and his team have seen all type of belly buttons in their research, and not all were as nice a this. (Photo:

In an interesting personal narrative of research he helped conduct, Rob Dunn writes in Scientific American that he and a few other scientists "went boldly where few had dared or really wanted to go before" -- the belly button.

As a whole, not much has been researched about this now closed orifice that once connected fetus to mother. But Dunn and a team from a variety of universities have found that not only does the average navel has 50 different species of bacteria, many of these species are very rare in nature.

The researchers found a lot of variety when it comes to differences in types of bacteria seen in one person's belly button to another. The more belly buttons they sampled and cultured bacteria from, the more differences they found.

"We began to more seriously wonder what explained the differences from one person to the next," Dunn wrote. "We were finding hundreds and then thousands of species, many of which appear new to science.

"The belly buttons reminded me of rain forests," Dunn continued later in the article. "In some tropical rain forests, even though there are many species of trees, a few species are both present in most forests and common when present. Those species have been called oligarchs; the belly buttons seemed to also have oligarchs too.

After more swabbing, culturing and identifying  the researchers found that while there are many different species found in different people's belly buttons, some species seem to matter more than others and are more prevalent.

The abstract of the group's research published in the journal PLOS One stated: "Although it remains difficult to predict which species of bacteria might be found on a particular human, predicting which species are most frequent (or rare) seems more straightforward, at least for those species living in belly buttons."

But this isn't all they found. Dunn wrote that one man said he hadn't washed his belly button in many years. It turns out he, and another person they sampled, not only had bacteria but organisms from the domain Archaea. To put this discovery into perspective, Archaea is commonly referred to as a domain full of single-celled organisms considered "extremophiles" -- those that live in harsh environments like extreme heat, cold, acidity, salinity and more.

What the scientists are having a hard time determining is why certain bacteria -- those that are less common -- are found in different navels. They've tried to make connections among types of bacteria and gender, age, ethnicity and even innie versus outie, but none of them seemed to lead to any trends.

Dunn wrote that understanding more about these microbes and their genetic make-up is important.

After all, "they affect your health and odor each and every day," he wrote. "We just don’t have a clue what determines who they are, yet."

See Dunn's full article for more fascinating information about what they found inside of belly buttons and the potential implications here. Check out the study published in PLOS One here.

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