Navels harbour an ecosystem of bacteria which is similar in their biodiversity to the world’s rainforests, a new study has claimed. US researchers found 2,368 species of bacteria, 1,458 of which may be new to science, after two years of literal navel gazing.
Just eight of these species were found in more than 70 per cent of individuals sampled. However, questions remain as to what factors govern which species will be found on which people, the Daily Mail reported. “The common, abundant species are from a relatively small number of evolutionary lines, indicating that they have evolved traits that make them at home on human skin,” said Rob Dunn of North Carolina State University.
“However, we are still trying to figure out what determines which of these species are found in a given person’s belly button,” Dunn said.
“We’ve looked at sex, age, ethnicity and a number of other factors — none of them are predictive of which species live in that person,” Dunn added.
Dunn and his team swabbed more than 500 belly buttons over the past two years, but concentrate on just 60 individuals for their study published in the journal PLoS One.
The researchers launched their project in part to investigate claims over recent years that the collection of organisms on human skin forms our first line of defence against pathogens. “We know that without these microbes our immune systems won’t function properly,” Dunn said.
“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,” Dunn added. The study identified 2,368 different phylotypes but only eight phylotypes - which the team dubbed ‘oligarchs’ - were found on at least 70 per cent of the study participants.
Those eight phylotypes - including varieties of Staphylococci, Corynebacteria, Actinobacteria, and Clostridiales, and Bacilli - were also among the most abundant, accounting for almost 50 per cent of the total abundance of bacteria in the samples.
Altogether, the researchers found that the average bellybutton among study participants contains 67 different phylotypes of bacteria.
“That makes the belly button a lot like rain forests,” Dunn told the National Geographic.
He explained that in any rainforest the range of flora will vary but scientists can count on a certain few dominant tree types present. “The idea that some aspects of our bodies are like a rain forest—to me it’s quite beautiful. I understand what steps to take next; I can see how that works,” he said.