Sharpee and her colleagues analyzed odor molecules found in four familiar and unmistakable scents: strawberries, tomatoes, blueberries and mouse urine. The researchers calculated how often and in what concentrations certain molecules turned up together in these scents. They then created a mathematical model in which molecules that occurred together frequently were represented as closer in space and molecules that rarely did so were farther apart. The result was a “saddle”-shaped surface—a hallmark of a field called hyperbolic geometry, which obeys different rules from the geometry most people learn in school.

— Tatyana Sharpee is a neurobiologist at the Salk Institute for Biological Studies in La Jolla. She and her colleagues are working on ways to map odors. Read more at Unraveling the Mathematics of Smell at Scientific American, or see the research paper at Hyperbolic geometry of the olfactory space at Science Advances.