James Watson and Francis Crick with their DNA model at the Cavendish Laboratories in 1953. Photograph by C. Barrington Brown. Courtesy C. Barrington Brown. To request permission to use this photo, please visit the Science Photo Library Web site at www.sciencephoto.com. Francis Crick (1916–2004) Francis Crick was among the many physicists who retrained themselves as molecular biologists from the 1930s through the 1950s. Crick’s graduate studies in physics were interrupted by World War II, during which Crick worked on naval mines for the British Admiralty. After the war he resumed his studies at Cambridge University’s Cavendish Laboratory, changing his focus from physics to molecular biology. Crick’s early work involved the X-ray crystallographic study of helical proteins, work that no doubt readied him to consider helices in other biomolecules. When James Watson joined his research group, the two became friends and fruitful collaborators. Using the X-ray crystallographic data of Rosalind Franklin (unbeknownst to Franklin), they formulated their double-helical model of DNA in 1953. This model allowed Watson and Crick to hypothesize a mechanism for DNA replication in which two strands of the double helix separate, each becoming the template for the production of a new strand. After discovering the double helix, Crick continued to study DNA, helping to decipher the genetic code. Crick, Watson, and Maurice Wilkins shared the 1962 Nobel Prize for physiology or medicine for elucidating the structure of DNA.