VSL:SCIENCE // Obsessive hand-washers: Don’t read this

The very first study to use “metagenomics” to analyze the hand’s microbial community has revealed that run-of-the-mill skin-culture tests have dramatically undercounted the germs we carry: On average, our hands host 150 species of bacteria — three times as many as inhabit the forearm, and far more than live in the mouth, the esophagus, or even the lower intestine.

One of the study’s many surprises was the discovery that women harbor 40 percent more bacterial species than men do — according to researcher Noah Fierer, that’s because men’s skin is more acidic. But when he was asked if men should worry about holding hands with their girlfriends, Fierer’s lab partner, Rob Knight, gave the correct answer. “I guess it depends on which girl,” he said.

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