Seymour Benzer

Seymour Benzer was an American molecular biologist who, in a series of experiments through the 1950s using the rII region of bacteriophage T4, a virus that infects bacteria, mapped the internal fine structure of a single gene in unprecedented detail, showing that a gene is not an indivisible unit but is itself built from a linear sequence of many smaller mutable sites, corresponding to what later became understood as individual nucleotide base pairs. This work helped establish the modern molecular understanding of gene structure and provided some of the first solid experimental evidence for the fine-grained, linear organization of genetic material. Later in his career Benzer shifted his research from bacteriophage genetics to behavioral genetics, turning to the fruit fly Drosophila melanogaster to search systematically for genes that influence behavior, and his laboratory at the California Institute of Technology identified mutant flies with disrupted circadian, or daily, activity rhythms, work that helped open the molecular study of the genes controlling biological clocks. Benzer's career, spanning physics, molecular biology and behavioral genetics, is often cited as an example of how fundamental discoveries can flow from moving deliberately between disciplines in pursuit of a clear experimental question.