Humanity

Sixteen years ago, when Calliope Holingue was in high school, she had a problem. Two, actually. She developed gastrointestinal symptoms severe enough to force her to give up running, plus she had a long history of anxiety and obsessive-compulsive disorder.

"And I wondered if maybe there was a link between my mental health and the GI symptoms I was experiencing," she recalls now.

Her doctors shrugged off her questions. "That led me to start reading a lot about the gut microbiome, the autonomic nervous system, and their connection with the brain and mental health," she says.

Today, Holingue has joined the ranks of scientists seeking to understand the interplay between the brain (and the rest of the nervous system) and the gut microbiome – that is the vast array of organisms, including bacteria, fungi and viruses, that thrive in the human gut.