In the intestines alone, the average person houses around 100 trillion microbes, and for every human cell in the body there are 10 microbial cells-making us more microbial than human. Scientific studies are beginning to show that these bacteria may be playing a much larger role in our lives than we originally thought. It appears that microbes may be influencing our brain and behavior, and many conditions, including schizophrenia, depression, and autism, have been linked to microbial abnormalities within the body. Elaine Hsiao, a 2015 National Geographic emerging explorer, is working on the cutting edge of this science to better understand how our microbiota influences our health. Is it possible that in the future we could treat health conditions with the right microbes?