The ciliatologist David Ledbetter Nanney was born in Abingdon, Va., on October 10, 1925, the son of T. Grady and Pearl Ledbetter Nanney. As an infant, David's father, a Baptist minister, moved from the Blue Ridge Mountains to the oil boom town of Wewoka, Oklahoma, capitol of the Seminole Nation. Although not highly educated in a formal sense, his family was nevertheless strongly oriented toward learning. After graduating high school and being excluded from military service due to the effects of childhood ailments, Nanney entered Oklahoma Baptist University in Shawnee, Okla., with the class of 1946. Studying literature and philosophy, he racked up a mixed academic record, and when his hopes of securing funding to continue his studies in the humanities fell by the wayside, he seized the opportunity to enter a field where funding was deeper and the need for graduate students more acute: zoology.

Following this rather uncommon path into science, Nanney entered Indiana University in the fall of 1946. In the post-war years, Indiana was home to a vibrant, often fractious collection of biologists, including the future Nobel laureates Herman J. Muller and Salvador Luria and the distinguished geneticist, Tracy M. Sonneborn. Despite Nanney's meager background in biology, Sonneborn agreed to become his research advisor, and fairly soon thereafter, Nanney became immersed in research on Paramecium aurelia, the ciliate with which Sonneborn was most closely identified. The Sonneborn lab included an exceptionally talented group of researchers, including John Preer (Sonneborn's first graduate student), Richard Siegel, P.K. Chao, and Ruth Dippell, all of whom went on to notable careers, and the group of experimental ciliatologists grew to include Ko Hiwatashi, Janine Beisson, Renzo Nobili, and Klauss Heckmann, notable figures in the study of Paramecium in Japan, France, Italy, and Germany, respectively. James Watson, a Luria student and future Nobel laureate, was another frequent associate.

During Nanney's years a grad student, Indiana was at the center of vigorous debate over the nature of the evolutionary process, with Sonneborn's theory of cytoplasmic inheritance pitted against Muller's "nucleic hegemony." Nanney's contributions to this debate were somewhat unexpected. In his dissertation research on quantitative differences in kappa particles between two mating types in Paramecium, he concluded that some form of epigenetic control system (to use a term that would not be coined until several years later), rather than cytoplasmic inheritance, was at work in regulating activity states in nucleic information. Reluctantly, and graciously, Sonneborn agreed. The resulting paper on epigenetic control systems, one of the first significant contributions of his career, earned Nanney a place in . Sonneborn, without doubt, was the most significant influence on Nanney's career, not only serving as his entry point into the field, but as a mentor, sounding board, and model on whom to build a research career.

Shortly after receiving his doctorate in June 1951, Nanney married Jean Kelly, a graduate student in piano and reviewed his career options. Though tempted by the offer of a National Research Council Postdoctoral Fellowship to work with Max Delbruck at CalTech and delve into phage genetics, Nanney declined in favor of a permanent position in the Department of Zoology at the University of Michigan, and shortly after his wedding, he packed up and moved.

By 1952, Nanney was searching for a new organism to develop into a model for genetic research, and through a colleague, Del Elliott, he began to work with Tetrahymena, the organism with he remained most closely associated throughout the rest of his career. His early research centered on the isolation of mating types, cytological studies of conjugation, and the genetics of mating type differentiation, laying the sort of solid foundation that has made Tetrahymena a model. He did, however, feel somewhat isolated in Michigan, sharing little with his colleagues, with Sonneborn continuing to serve as his primary scientific ally and critic. At Michigan, Nanney also became interested in reforming undergraduate biological education to keep pace with rapid developments in the field. His ideas for curricular reform at Michigan, however, were consistently thwarted by what he saw as an ossified system. In this aspect, too, Michigan seemed less than an ideal match.

When his first sabbatical cycle rolled around in 1958, Nanney was forced to turn down a Fulbright Fellowship to work with Boris Ephrussi in Paris (fearing that it would make him eligible for the draft), but he returned to thoughts of CalTech, and received funds to spend a year working there with Ray Owen. Removed from Ann Arbor, Nanney's frustrations with the pace of curricular reform reached a head, and when offered a position at the University of Illinois, where the varied departments that dealt with biology had recently been consolidated into a new School of Life Sciences (SOLS), he jumped. The presence of Luria, Marcus Rhoads, and Sol Spiegelman sweetened the deal.

Nanney's arrival at Illinois coincided with the major upsurge of support for science education in the wake of Sputnik and the Cold War, giving him an opportunity to act upon his curricular ideas. The National Science Foundation provided significant funding for Illinois to re-emphasize the undergraduate laboratory experience, stressing a model curriculum built around the "mantra" of the Cell, the Organism, and the Population. While the Illinois project never became the model for others to follow as it was intended, the new curriculum was adopted by the honors program in SOLS and was considered a long-term success. In addition to his curricular work at Illinois, Nanney also served as a member of the Biological Sciences Curriculum Study group, which resulted in the publication of his widely-adopted textbook .

With the rapid evolution of the life sciences since the 1960s, reorganizations of the schools and departments became increasingly necessary, and increasingly common. Nanney was involved in several later initiatives to reformulate biological instruction at the university and reorganize the school, taking part in a systematic study of how SOLS faculty related to one another in theory and practice. The result was a series of departmental realignments and reorganizations. Returning from a Humboldt Fellowship in Munster, Germany, in 1984, Nanney discovered that his department, then called Genetics and Development, had actually been disbanded. Rather than return to the reorganizational fray, he accepted an opportunity to join the interdisciplinary Center for Advanced Studies, which eventually spawned a Science and Technology Studies program in which Nanney was active. Nanney has subsequently written at length about the history of protistology, Sonneborn, ciliate genetics, and evolutionary biology.

In Illinois, Nanney built an active research program in Tetrahymena. From the analysis of cortical pattern during the 1960s and 1970s, he and his lab studied genic control, cortical variation and the constancy that "lurks behind this variation," and by the 1970s, he and his students Dennis Borden and Elizabeth Miller, along a colleague Greg Whitt, began work on isozymes to sort out species in Tetrahymena. The precision he was able to bring in distinguishing strains paved the way for valuable work in the study of molecular evolution, including his later work comparing RNA sequences. Nanney's publications contributed to a growing debate over the rates of phenotypic versus molecular evolution, with Nanney arguing that in ciliates, at least, evolution at the molecular and morphological levels are relatively uncoupled.

During his career, Nanney served on editorial boards of several journals, including the , , , , and , and he was active in a number of professional organizations, including the American Genetic Association (president, 1982), Genetics Society of America, Society of Protozoologists, and the International Society for Evolutionary Protistology. Since his retirement in 1991, he has remained in Urbana and continues to write on the history of his discipline.