The human intestine is a swirling and churning environment that is host to microbial communities as diverse as those found in the Amazon rain forest. And like the regions beneath the soils that carpet the rain forest floor, much of what lies within the gut remains unexplored.

A series of papers in the March 28 issue of Science delves into this scientific frontier and begins to unravel the secrets of the complex and highly evolved microbial communities that teem throughout the length of our intestines.