Much of the beauty—and challenge—of biology lies in its complexity. That's especially true in the microbial world, where hundreds or thousands of different bacterial species may co-exist in a patch of soil or in a section of the human gut. Each species has its own way of life, but each also interacts with the others to shape the ecosystem. But is there hope for some order in that complexity? A new paper in Science co-authored by Mikhail Tikhonov, an associate professor of physics at Washington University in St. Louis, has pierced through the apparent chaos to find surprising levels of predictability in microbial systems.