The X-Ray Crystallographer Whose Photo 51 Gave Watson and Crick the DNA Helix and Whose Name Was Left Off the Nobel

Rosalind Franklin (1920–1958) was the senior X-ray crystallographer in Maurice Wilkins’s DNA research group at King’s College London from 1951. She had taken her PhD at Cambridge in 1945 on the porosity of coal, then spent four years in Paris at the Laboratoire Central des Services Chimiques de l’État developing the X-ray diffraction techniques that would dominate the rest of her career. King’s hired her specifically to apply those techniques to DNA fibres.

The working relationship with Wilkins broke down within months. Wilkins had assumed Franklin would be his junior assistant; Franklin had been recruited as an independent senior researcher. Neither had been told the other’s understanding of the appointment.

Photo 51

On 2 May 1952 Franklin and her graduate student Raymond Gosling took an X-ray diffraction photograph of the hydrated B-form of DNA. The exposure required approximately 100 hours of continuous X-ray illumination. The resulting image — labelled Photo 51 — showed an unmistakable helical cross pattern with a measured 3.4 ångström repeat distance along the fibre axis and a 34 ångström helical pitch.

The image meant DNA was a helix. The dimensions specified the geometry. Anyone with the photograph and the standard Cochran-Crick-Vand helical diffraction theory (published 1952) could in principle solve the structure.

January 1953

On 30 January 1953 Wilkins showed Photo 51 to James Watson, who was visiting from Cambridge. Franklin had not authorised this. Watson took the structural information back to Cambridge, where he and Francis Crick built a physical model of the double helix within six weeks.

The 25 April 1953 issue of Nature contained three back-to-back papers: Watson and Crick’s structural proposal, Wilkins’s experimental support, and Franklin and Gosling’s separate X-ray data — written as if the three groups had reached the same conclusion independently. Franklin had not been told that Watson and Crick had seen her photograph.

She moved to Birkbeck College in March 1953 and spent the remaining five years of her career on the structure of the tobacco mosaic virus and the polio virus. The viral work would have been a Nobel candidate in its own right.

Death

Franklin was diagnosed with bilateral ovarian cancer in autumn 1956. She died on 16 April 1958 at the Royal Marsden Hospital, aged 37. The cancer was almost certainly caused by years of X-ray exposure without modern protective equipment — the same mechanism that had killed Marie Curie twenty-four years earlier.

The 1962 Nobel Prize in Physiology or Medicine was awarded jointly to Watson, Crick, and Wilkins for the discovery of the structure of DNA. Nobel Prizes are not awarded posthumously; Franklin had been dead for four years. Her name does not appear on the citation.

The Royal Society’s 2003 Rosalind Franklin Award is the most prestigious British prize for early-career women scientists.