Hood also made generative discoveries in the field of molecular immunology. His studies of the amino acid sequences of immunoglobulins (also known as antibodies) helped to fuel the 1970s’ debate regarding the generation of immune diversity and supported the hypothesis advanced by William J. Dreyer that immunoglobulin (antibody) chains are encoded by two separate genes (a constant and a variable gene). He (and others) conducted pioneering studies on the structure and diversity of the antibody genes. This research led to verification of the "two genes, one polypeptide" hypothesis and insights into the mechanisms responsible for the diversification of the immunoglobulin variable genes.