b'Evolutionary biologists have long probed how genes encode an individuals chances for successTheir ultimate goalis to or fitnessin a specific environment. To revealuse this predictivepower to a potential evolutionary trajectory, biologists measure the interactions among genes to seeengineerthe microbiome.which combinations are most successful. An evolving organism should take the most successful path. This concept is called a fitness landscape,interactions. Their mathematical method measures and various mathematical techniques have beeninteractions in multidimensional space, where each developed to describe it. Like genes in a genome,species has its own dimension. gut microorganisms interact, but there has not been37a widely accepted mathematical framework to mapThe team is now comparing different landscapes, these ecological interaction patterns to host fitness. which they hope will point to general principles of how microbial interactions affect host health. Ludingtons To measure these complex interactions, Ludingtonnext goals are to uncover molecular mechanisms and coworkers developed a new mathematicalby which hosts and their complex gut microbial framework. They built a technique that describescommunities interact. The multiscale approach the ecology of a microbiome, coupled to its host,connects the molecular interactions between microbes by calculating the geometric structure of theto the physiology of the whole animal. Will Ludington joined the Carnegie staff in June 2018 from his lab at U.C.-Berkeley.Image courtesy Navid Marvi, Carnegie Institution for Science'