At some point, we all became germophobes: The shelves of our stores abound with disinfectant, antibacterial soap, and hand sanitizer — so much so that public-health authorities have long worried that humans are destroying helpful bacteria along with the harmful ones. A groundbreaking new study called the Human Microbiome Project only amplifies those concerns. The Broad Institute in Cambridge and three other research centers spent five years sequencing the genes of bacteria and other microorganisms collected from more than 200 healthy volunteers. The project found 10,000 species of microbes and over 8 million genes from microbes. The 100-trillion-odd microorganisms normally found in a typical human can weigh 2 to 6 pounds per person.
Inevitably, some news coverage emphasized the ick factor. “Even healthy humans can host 10,000 microbe species,” declared one headline. But squeamishness is misplaced. Individuals have different mixes of organisms riding around inside them, the study found, and those differences may help explain conditions from eczema to obesity. Preserving health may be less a matter of killing off the enemy, like in a war movie, than keeping a delicate ecosystem in balance, as in a National Geographic documentary. So don’t fret about all those bacteria in your body; it’s like traveling through life with trillions of friends.