A mounting tide of scientific evidence suggests that the old adage from Aesop's fables — "You are known by the company you keep" — also applies to the trillions of microscopic bacteria and viruses that live on the human body. Humanity's invisible but constant companions — more bacteria hang out on the palms of your hands than there are people on Earth — is the topic of an article in the current edition of Chemical & Engineering News (C&EN), the weekly news magazine of the American Chemical Society.
C&EN associate editor Sarah Everts notes in the article that the astonishing diversity of microbes inhabiting every inch of the skin and parts of the interior profoundly influences your quality of life — mostly for good — from cradle to grave. Microbes protect people from disease, make essential vitamins, and provide digestive enzymes needed to break down plant fibers for energy. Microbes also may have a say in whether people are skinny or fat and how they smell.
In the past three years, scientists have begun several large projects to map the diversity and activities of these microbes in hopes of linking them to health and disease. The projects include the National Institutes of Health's Human Microbiome Project and the European Union's Metagenomics of the Human Intestinal Tract. These and other projects are starting to reveal that every part of the body has its own ecosystem, much like the diversity of landscapes on Earth.