GUT INSTINCT.

When Larry Smarr pulls out a plastic model of his colon that he made with a 3D printer and simultaneously projects on a screen behind him a magnetic resonance image of his guts, it becomes abundantly clear that he believes a presentation benefi ts from a most personal touch. Smarr started out as an astrophysicist and has followed an intriguing career arc from probing black holes to his own bowels. Three decades ago, he helped establish a network of supercomputer centers in the United States and was a cyber pioneer. (His grad student made the fi rst Internet browser.) Today, the University of California, San Diego, professor runs the California Institute for Telecommunications and Information Technology (Calit2), a multidisciplinary center meshing nanotechnology with wireless communications, genomics, and computer science. Calit2, Smarr hopes, will become a force in personalized medicine—and his colon has become the centerpiece of a campaign to show the world how patients can take a more active role in their own health care by exploiting technological advances to collect genomic, biochemical, and physical data. For several years, Smarr has intensely monitored his health, a preoccupation that in 2010 helped him diagnose, ahead of his doctors, infl ammatory bowel disease. In a talk he has given everywhere from Harvard Medical School to the U.S. National Institutes of Health, Smarr shows startling graphics that chart myriad biochemical and physical perturbations in his body linked to what he believes is a condition with features resembling Crohn’s disease and ulcerative colitis. He paid a company to measure blood markers that standard tests ignore, and, with the help of the J. Craig Venter Institute’s genomic analysis of his fecal samples, he has documented how his body has killed off many benefi cial bacterial species in his gut while allowing harmful ones to thrive. His plastic colon and the MRI scans fi ll out the sad picture of a gut gone haywire. By blending systems biology and personal drama, Smarr’s talks bowl audiences over. He speaks plainly; is passionate about his data (without bathing in self-pity about his disease); and makes the abstract concrete with his plastic colon, a prop that he passes around the audience. “I’ve given hundreds if not thousands of talks on so many different topics, and I’ve never had the kind of reaction I’ve had in the last few years,” Smarr says. “When you talk about what’s going on inside the human body, everyone relates.” A critical moment in his talk comes when he emphasizes that 90% of the DNA in our bodies is bacterial, and we can now sequence that foreign material to understand our health. “A lot of the reaction is, ‘How did I miss the memo that 90% of the cells in my body aren’t human?’ ” Smarr says. “It’s a moment of massive discovery essential to every single human on Earth. These moments don’t come along more than a couple times in a century.” Few scientists have the luxury of drawing on data from their own bodies to captivate an audience, but one technique of Smarr’s is widely applicable: Don’t miss the forest for the trees. He suggests scientists imagine themselves as a baker—not a fl our specialist—explaining how to make a fancy cake. “It’s the integration of several ingredients over time,” he says. “We aren’t trained to think that way. We’re trained just the opposite.” –J. C.