The learning curve of wine can be steep. Grape varieties? Thousands. Soils? More than your brain can hold. Regions? Buckle up and get your map out. But one mercifully simple part of wine education is yeast. There’s really only one yeast to memorize: Saccharomyces cerevisiae, usually just called yeast. Those studying for wine exams don’t have to spend a Saturday highlighting books about yeast to get a passing grade.

However—perhaps to the chagrin of future wine students—winemakers have increasingly started to experiment with lesser-known yeasts. Tempted by the prospect of new flavors or reduced reliance on sulfur, these winemakers seek to reintroduce non-Saccharomyces yeasts that have been largely banished from winemaking by better technology and increased sanitation. Meanwhile, laboratory research into the properties of these yeasts has provided unprecedented knowledge about what they can do for winemaking.

Technically, yeast just means “single-celled fungus.” In other words, yeast is a name for a fungal growth form rather than a single family or species. Single-celled fungi have evolved separately in many different branches of the fungal family tree, which means yeasts are a polyphyletic group—that is, they’re grouped by traits they share rather than evolutionary relationships. But when talking about wine yeast, we’re usually talking about a single species: Saccharomyces cerevisiae. Other yeasts in the Saccharomyces genus are used in winemaking—for example, S. beticus, which is responsible for the flor that grows on the surface of Sherry—but S. cerevisiae is unquestionably the most popular.

What makes S. cerevisiae unique? Why did it edge out other single-celled fungi to become the star player in winemaking and brewing? When it comes to wine, S. cerevisiae has many advantages. It can grow anaerobically—that is, without oxygen—and, compared with other