Rosalind Franklin was a British chemist and X-ray crystallographer whose work was central to discovering the structure of DNA. Born on July 25, 1920, in London, she produced the famous “Photo 51,” an X-ray image that revealed DNA’s double helix shape and provided critical measurements that James Watson and Francis Crick used to build their model. She died of cancer on April 16, 1958, at age 37, four years before Watson, Crick, and her colleague Maurice Wilkins received the Nobel Prize for the discovery.
Education and Early Career
Franklin studied natural sciences at Cambridge University, where she earned her PhD in 1945. Her doctoral thesis explored the density and porosity of coal, a topic that sounds unglamorous but proved scientifically rich. She discovered that when coal is heated to carbonizing temperatures (600 to 1,000 degrees Celsius), its porosity increases even as its chemical reactivity decreases. She also found that at higher temperatures, the tiny pores in coal progressively shut out larger molecules first, then smaller ones, effectively filtering substances by molecular size.
This work led her to divide coals and other solid organic materials, including plastics, into two categories: those that convert readily into graphite when heated, and those that resist this transformation. She figured out that non-graphitizing carbons form a strong network of cross-links between their tiny crystal structures, physically preventing the material from rearranging into graphite. These non-graphitizing carbons are low-density, highly porous, and extremely hard. Her classification system became foundational in carbon science and remained relevant to materials research for decades.
The Work That Changed Biology
In 1951, Franklin joined King’s College London to study the structure of DNA using X-ray crystallography, a technique that bounces X-rays off a substance to reveal its molecular arrangement. She was exceptionally skilled at preparing samples and reading the resulting images. By May 1952, she and her graduate student Raymond Gosling captured Photo 51, an X-ray diffraction image of the “B” form of DNA. The image was strikingly clear and contained a distinctive X-shaped pattern that pointed directly to a helical structure.
Photo 51 wasn’t just a pretty picture. It contained precise measurements: a diameter of 20 angstroms, a distance of 3.4 angstroms between the chemical bases stacked inside the helix, and a repeat distance of 34 angstroms. It also suggested the helix had a slope of about 40 degrees and was likely made of two intertwined chains rather than three. These were exactly the numbers needed to build an accurate physical model of DNA.
How Watson and Crick Got the Data
The story of how those measurements reached Watson and Crick is one of the most debated episodes in the history of science. On January 26, 1953, Franklin showed Photo 51 to Maurice Wilkins, a colleague at King’s College with whom she had a notoriously difficult working relationship. Just four days later, on January 30, Wilkins showed the photograph to James Watson at Cambridge. Watson later wrote that seeing the image immediately confirmed the vital statistics he and Crick needed to build their B-form model.
Franklin was not told that her data had been shared. Watson and Crick published their landmark paper on the double helix structure in April 1953, and while Franklin published her own supporting X-ray data in the same issue of Nature, the full extent of her contribution was not acknowledged at the time. Watson’s 1968 memoir, “The Double Helix,” portrayed Franklin dismissively, describing her appearance and temperament rather than her scientific ability. This account shaped public perception of her for years and sparked a long-running reassessment of who deserved credit for the discovery.
Virus Research After DNA
Franklin left King’s College in 1953 and moved to Birkbeck College London, where she turned her X-ray skills to studying viruses. She did important work on tobacco mosaic virus, mapping its structure in detail, and later began investigating the structure of the polio virus. Her team’s research on virus architecture contributed to understanding how viral protein shells are assembled, work that had implications for vaccine development. This period was arguably the happiest of her career; she was leading her own lab, publishing prolifically, and working with colleagues who respected her.
Death and the Nobel Question
Franklin was diagnosed with ovarian cancer, likely linked to the extensive X-ray radiation exposure involved in her crystallography work. She continued working through her illness but died on April 16, 1958, at 37 years old.
In 1962, Watson, Crick, and Wilkins shared the Nobel Prize in Physiology or Medicine for determining the structure of DNA. Franklin received no mention. The Nobel Prize cannot be awarded posthumously, and nominations for deceased individuals are not accepted. Even under the pre-1974 rules, which allowed posthumous awards only if the person had been nominated before February 1 of the prize year, Franklin would not have qualified unless someone had put her name forward. Whether the Nobel committee would have included her had she lived remains one of science’s most persistent “what ifs.”
Franklin’s reputation has grown enormously since the 1990s, aided by Brenda Maddox’s 2002 biography “Rosalind Franklin: The Dark Lady of DNA” and increasing scrutiny of how her contributions were minimized. She is now widely recognized not as a footnote to the DNA story, but as one of the scientists who made the discovery possible.