Entomologists Ted Schultz and Seán Brady at the Smithsonian's National Museum of Natural History have been providing new insight into the agricultural abilities of ants and how these abilities have evolved throughout time. Using DNA sequencing, the scientists were able to construct an "evolutionary tree" of fungus-growing ants, which revealed a single pioneering ancestor that discovered agriculture approximately 50 million years ago. In the past 25 million years, four different specialized agricultural systems have evolved, leading to the most recently evolved and best-known fungus-growing ant species--"leaf-cutter ants."