Researchers at the Baylor College of Medicine have found the key to longevity in Caenorhabditis elegans (C. elegans) worms — and maybe, someday, humans. The team noticed that genetically identical worms would occasionally live for much longer, and looked to their gut bacteria to find the answer. They discovered that a strain of E. coli with a single gene deletion might be the reason that its hosts’ lives were being significantly extended.

This study is one among a number of projects that focus on the influence of the microbiome — the community of microbes which share the body of the host organism — on longevity. Ultimately, the goal of this kind of research is to develop probiotics that could extend human life. “I’ve always studied the molecular genetics of aging,” Meng Wang, one of the researchers who conducted the study, told The Atlantic. “But before, we always looked at the host. This is my first attempt to understand the bacteria’s side.”

Even in cases like this, where it seems fairly obvious that the microbiome is influencing longevity, parsing out the details of how and why this happens among a tremendous variety of chemicals and microbe species is extremely complex. The team, in this case, was successful because they simplified the question and focused on a single relationship.