How changing a body's microbes leads to illness

Claire M. Fraser, PhD, in this TED talk explains how microbes affect our lives. We are more obsessed with cleanliness than ever: we use antibacterial cleansers, we keep our children away from dirt, and we give out antibiotics with little regard for long-term effects. But in the process, we are altering our microbiota, the microbes that live on and inside us. And it's causing us to be more sick.