The microbes living in and on your body outnumber your own cells by a factor of 10 to 1. That's approximately $$10^{13}$$ microbes -- for a visual the microbes of your gut could fill a can to overflowing. Recent evidence suggest that these microbes influence far more than the metabolic activities in the gut; experiments in animal models show that microbes alter social behavior, intelligence, susceptibility to disease, and overall health and fitness. This course will survey new findings in the microbial underpinnings of animal and human health and behavior through literature, simple hands-on experiments, and lecture.