Brewing and wine production are among the oldest technologies and their products are almost indispensable in our lives. The central biological agents of beer and wine fermentation are yeasts belonging to the genus Saccharomyces, which can accumulate ethanol. Recent advances in comparative genomics and bioinformatics have made it possible to elucidate when and why yeasts produce ethanol in high concentrations, and how this remarkable trait originated and developed during their evolutionary history. Two research groups have shed light on the origin of the genes encoding alcohol dehydrogenase and the process of ethanol accumulation in Saccharomyces cerevisiae.