Annual crops have been domesticated for nearly 10,000 years, whereas no commercial perennial grains have yet been developed. It is unclear exactly why perennial grains were not domesticated alongside annual grains during the agricultural revolution. Annuals may have been more predisposed to domestication for several reasons. For one, wild annuals were likely easier targets for early domestication efforts because they generally have greater single-year yields than wild perennials. Because the fitness of annual plants depends on the reproductive output of a single year, annuals naturally invest heavily in seed production (typically the product of interest for agriculture). In contrast, perennials have to balance seed production with overwinter survival in any given year and thus tend to produce lower yields per year. Second, annual plants have a shorter generation time, facilitating faster gains through the artificial selection process. Third, early agriculture used tilling to clear fields for the following year’s crop and the practice of annual tilling, which clears the soil of existing plants in preparation for new ones, is not compatible with perennial grains. Finally, once annual grains were domesticated there was a reduced incentive to pursue the domestication of new perennial grains.