This story appeared in the November 2020 issue as "Bacteria and the Brain." Subscribe to Discover magazine for more stories like this.
It’s not always easy to convince people that the human gut is a sublime and wondrous place worthy of special attention. Sarkis Mazmanian discovered that soon after arriving at Caltech for his first faculty job 14 years ago, when he explained to a local artist what he had in mind for the walls outside his new office.
The resulting mural greets visitors to the Mazmanian Lab today. A vaguely psychedelic, 40-foot-long, tube-shaped colon that’s pink, purple and red snakes down the hallway. In a panel next to it, fluorescent yellow and green bacteria explode out of a deeply inflamed section of the intestinal tract, like radioactive lava from outer space.
The mural is modest compared with what the scientist has been working on since. Over the last decade or so, Mazmanian has been a leading proponent of the idea that the flora of the human digestive tract has a far more powerful effect on the human body and mind than we thought — a scientific effort that earned him a $500,000 MacArthur Fellowship “Genius Grant” in 2012. Since then, Mazmanian and a small but growing cadre of fellow microbiologists have amassed a tantalizing body of evidence on the microbiome’s role in all kinds of brain disorders, including schizophrenia, Alzheimer’s disease, Parkinson’s disease and depression.
