Larry Smarr, Founding Director, CALIT2, examines the 90% of cells in the body that aren’t human, most of which reside in the large intestine. A recent study used metagenomic sequencing of DNA from stool samples to identify the myriad species of microbes in the gut. He advises doctors to view gut microbes not as an enemy, but as an ecological garden. Read more about Larry Smarr. Filmed at Exponential Medicine, in February 2013, at Singularity University.