The human body is an ecosystem, Lita Proctor, director of the Human Microbiome Project at the US National Institutes of Health, tells Rob Stein from NPR's Morning Edition as he embarks on a tour of the human microbiome. While there are distinct habitats, Stein notes that the microbes living in each do communicate with one another and with host cells.
In the segment, Stein finds that the mouth is home to diverse microorganisms — the Amazonian jungle of the body, he calls it — and Proctor notes that the microbes living on the roof of the mouth differ from those found on the tongue. Similarly, the armpit is also a lush area for microorganisms. The most diverse area, Stein adds, is the gut.
"There is apparently a role for the microbiome in the way diet is metabolized and how fat is deposited," Proctor says, adding that there is a close link between changes in the microbiome and obesity.
Stein notes that obese people appear to have less diverse microbiomes than lean people do. He adds that there also tentative links between antibiotic use, increased cleanliness, and other facets of modern life, like increased C-sections, that may lead to less contact with microoganisms and thus less diverse microbiomes and then, possibly, to diseases like obesity or asthma.