Hirsch believed that behaviors were so complex they could not be explained as the action of single genes, Benzer thought behaviors might be directed by single genes. Both researchers tried their ideas out on "Drosophila". Hirsch artificially selected for behaviors of interest over many generations, while Benzer used methods to isolate mutants for a particular behavior. Benzer and Hirsch's competing philosophies developed behavioral genetics, and helped it become a legitimate area of study in the scientific community.