Eric Alm bursts into the Massachusetts Institute of Technology lab and grabs a small, maroon-colored sports duffel bag. "Give me seven and a half minutes," he says with a sense of urgency. "I'm taking a sample and I know exactly how long that takes me." Into the duffel bag he stuffs a disposable plastic commode about the size of a fedora hat, latex gloves, an autoclaved sampling tube, and a biohazard container.
"I've been extremely stressed out today," Alm says.
"Have you been taking your blood pressure?" Lawrence David asks eagerly.
"Yeah, it was really high. This should be interesting."
Alm, an evolutionary microbiologist, and David, his graduate student, are engaged in what they're calling the HuGE (Human Gut Ecology) Project—an effort to track how the microbial communities in their own digestive tracts change over time. "The point is to figure out the normal dynamics of what's probably the densest ...
