Narrator: This is Science Today. About 5 pounds of your body weight is from bacterial cells, not human cells. Now, before you get spooked, realize that this is a good thing.
Pollard: Just in a healthy normal individual, we couldn't do all the things we need to do. We couldn't extract all the nutrition from our food, for example, without certain microbes living in our guts. So, they are us.
Narrator: Katherine Pollard is an investigator at the University of California, San Francisco-affiliated Gladstone Institutes and she is part of a consortium of scientists mapping the human body's bacterial ecosystem. It's called the Human Microbiome Project.
Pollard: We're really interested in two things going forward: moving from describing what organisms are there to really understanding what they're doing and figuring out what all the proteins are in the genomes of the organisms. And the other thing that we're interested in, going forward, is moving from healthy individuals to understanding disease.
Narrator: For Science Today, I'm Larissa Branin.