David L. Baltimore (born 7 March 1938) is an American biologist, university administrator, and Nobel laureate in Physiology or Medicine. He served as president of the California Institute of Technology (Caltech) from 1997 to 2006, and is currently the Robert A. Millikan Professor of Biology at Caltech. He also served as president of Rockefeller University from 1990 to 1991, and was president of the American Association for the Advancement of Science in 2007. As is traditional in the AAAS, he now serves as the Chairman of the Board of Directors.
Baltimore was born to Gertrude Lipschitz and Richard Baltimore in New York City. He graduated from Great Neck High School in 1956, and credits his interest in biology to a high-school summer spent at the Jackson Laboratory in Bar Harbor, Maine. He earned a BA at Swarthmore College in 1960, and received his Ph.D. at Rockefeller University in 1964. After postdoctoral fellowships at Massachusetts Institute of Technology (MIT) and Albert Einstein College of Medicine and a non-faculty research position at the Salk Institute, he joined the MIT faculty in 1968.
In 1975, at the age of 37, he shared the Nobel Prize for Physiology or Medicine with Howard Temin and Renato Dulbecco. The citation reads, "for their discoveries concerning the interaction between tumour viruses and the genetic material of the cell." At the time, Baltimore's greatest contribution to virology was his discovery of reverse transcriptase (RTase or RT). Reverse transcriptase is essential for the reproduction of retroviruses such as HIV and was also discovered independently, and at about the same time, by Mizutani and Temin.