Harold E. Varmus is an American scientist who won a share of the 1989 Nobel Prize in Physiology or Medicine. Along with J. Michael Bishop, he discovered the cellular origin of retroviral oncogenes and developed a new theory of the origin of cancer, which holds that the disease arises from mutations in some of our own normal genes. The duo also found out that the genes that are susceptible to such mutations are closely related to genes in a number of cancer-causing viruses. Born as the son of a physician, he was expected to follow in his father’s footsteps. But as a young man Varmus was more interested in literature and went on to earn a graduate degree in English at Harvard University. However, he changed his mind and entered the Columbia University College of Physicians and Surgeons, earning his MD in 1966. He was first exposed to laboratory science when he joined the Public Health Service at the National Institutes of Health where he performed research under Ira Pastan. He later began post-doctoral studies with Michael Bishop at University of California, San Francisco, under a fellowship from the California Division of the American Cancer Society. His scientific collaboration with Bishop led to many significant medical discoveries that are of much importance to the study of cancer causing viruses.