We are made up of 70 trillion cells, more than half of which are not part of the human body - they are microbes.  Microbes play a critical role in keeping us healthy, protecting us from pathogens, boosting our immune system, and even fighting off stress. It turns out that microbes also play a pivotal role in keeping the earth’s soil healthy. I talk with Dr. Rupa Marya, who is no average doctor. Rupa is a forceful social justice advocate, a world-renowned musician, an urban farmer, a mother to two incredible kids, and Associate Professor of Medicine at UCSF, who is investigating how soil health is connected to people’s health.