Photo 51 was Rosalind Franklin's. Watson saw it without her knowledge. The Nobel Prize went to three men. Franklin died before it was awarded. The controversy never died.
| Category | Watson & Crick | Rosalind Franklin |
|---|---|---|
| Primary method | Model building — constructing physical molecular models and testing against data | X-ray crystallography — direct experimental measurement of molecular structure |
| Key data source | Franklin's Photo 51 and MRC report; Chargaff's base-pairing rules | Independently gathered; her own crystallographic work on DNA A and B forms |
| 1953 Nature paper | A structure for deoxyribose nucleic acid — proposed the double helix | Published in same issue with independent experimental confirmation of helical form |
| Awareness of use | Saw Photo 51 via Wilkins; saw MRC report via Max Perutz — neither disclosed to Franklin | Unaware her data had been shared until after Watson and Crick's model was published |
| Nobel outcome | Watson, Crick, Wilkins — Nobel Prize in Physiology or Medicine, 1962 | Died April 1958 — four years before the Nobel was awarded; ineligible posthumously |
| Historical credit | Celebrated in textbooks as discoverers of the double helix | Recognition grew from 1970s onward; now widely acknowledged as essential contributor |
The story of DNA's structure is one of the most dramatic in the history of science — a four-way competition between laboratories in Cambridge (Watson and Crick at the Cavendish), London (Rosalind Franklin and Raymond Gosling at King's College, and separately Maurice Wilkins also at King's), and Pasadena, California (Linus Pauling at Caltech). The prize was the structure of the molecule that carries genetic information — the physical explanation of heredity and the foundation of molecular biology.
James Watson arrived in Cambridge in 1951 as a 23-year-old American postdoctoral researcher. Francis Crick was a 35-year-old PhD student who had spent the war years working on naval mines. They were an unlikely pair: Watson brash and ambitious, Crick extroverted and theoretically brilliant, both convinced that the structure of DNA was the most important unsolved problem in biology. Their method was model building — constructing three-dimensional physical models of molecular structures and testing them against the available data, much as Linus Pauling had done in discovering the alpha helix structure of proteins in 1951.
Rosalind Franklin had arrived at King's College London in 1951, hired to bring her expertise in X-ray crystallography to the DNA problem. She was meticulous, technically brilliant, and committed to letting the data lead. She did not speculate beyond what her measurements could support. By early 1952 she had produced the clearest X-ray diffraction images of DNA ever obtained, and she was methodically building toward a complete structural analysis.
In May 1952, Franklin and her student Raymond Gosling produced Photo 51 — an X-ray diffraction image of the B form of DNA taken with an exposure time of over 60 hours. The image showed with extraordinary clarity the characteristic X-shaped pattern produced by a helical molecule. To a trained eye, it was decisive. The molecule was a helix; the cross pattern gave the pitch and diameter; the central solid regions indicated that the phosphate backbone was on the outside.
In January 1953, Maurice Wilkins showed Photo 51 to James Watson. Wilkins had not asked Franklin's permission. Whether he was within his rights to do so — the photograph was taken using laboratory equipment and might technically have been considered institutional property — has been debated ever since. What is beyond dispute is that Franklin did not know her image was being shared. Watson's own account, in his 1968 memoir The Double Helix, records his reaction: "The instant I saw the picture my mouth fell open and my pulse began to race." He left without taking notes, relying on his memory of the measurements encoded in the image.
Around the same time, Crick received from Max Perutz a Medical Research Council report that contained Franklin's detailed quantitative measurements of the DNA helix — the unit cell dimensions, the water content, the spatial group symmetry. Perutz later said he did not realize the report was confidential when he shared it. The information it contained was precisely what Watson and Crick needed to refine and confirm their model.
Watson and Crick submitted their paper on the structure of DNA to Nature in April 1953. It is 900 words long — one of the most consequential short documents in scientific history. The famous understatement near the end — "It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material" — casually describes the mechanism by which life replicates itself.
The paper appeared on April 25, 1953, in the same issue as papers by Franklin and Gosling, and by Wilkins, Stokes, and Wilson — three papers on the same molecule in the same journal issue, the experimental evidence and the structural model published simultaneously. Watson and Crick's paper acknowledged that they had been "stimulated by a general knowledge" of Franklin and Wilkins's unpublished results. This was a characteristically oblique acknowledgment of the data they had seen without her knowledge.
Franklin's own paper in that same issue provided independent experimental support for the helical structure. She died not knowing the full extent to which her data had been used. Watson's memoir, published in 1968, presented her as an obstacle — difficult, uncooperative, unlikely to understand the helical model — a caricature that drew stinging rebukes from Crick himself, who called Watson's portrayal "unjust."
Rosalind Franklin died on April 16, 1958, of ovarian cancer, aged 37. She had continued to work at Birkbeck College London after leaving King's, producing landmark research on tobacco mosaic virus and other viruses. She died with no awareness that her DNA work had been compromised, and she died still largely unrecognized for what her photographs had contributed.
The Nobel Prize in Physiology or Medicine was awarded in 1962 to Watson, Crick, and Maurice Wilkins "for their discoveries concerning the molecular structure of nucleic acids and its significance for information transfer in living material." The Nobel Committee limits each prize to a maximum of three living recipients. Franklin was dead. Wilkins — whose relationship with Franklin had been famously difficult — received the third share.
Whether Franklin would have been nominated had she lived is an open question. Aaron Klug, her close colleague at Birkbeck and the man who continued her work on viruses, won his own Nobel in 1982. He spent decades working to rehabilitate her reputation. By the late twentieth century, the consensus among historians of science had shifted decisively: Franklin's contribution was essential, her data was decisive, and the failure to credit her adequately — in the 1953 paper, in Watson's memoir, and implicitly in the Nobel selection — represents the most consequential injustice in the prize's history.
Franklin's contribution was essential and uncredited — the most consequential injustice in Nobel Prize history. The double helix model is correctly attributed to Watson and Crick in the sense that they proposed it and built it. But the empirical foundation on which it rested — the precise measurements of DNA's dimensions, the identification of the helical form, the location of the phosphate backbone — was Franklin's. Without Photo 51 and the MRC report data, Watson and Crick could not have solved the structure when they did. Watson acknowledged this privately and elliptically in the 1953 paper; he obscured it publicly in The Double Helix. The Nobel Committee, bound by its own rules on posthumous awards, could not correct the record. History must.
An X-ray diffraction image of DNA taken by Rosalind Franklin and Raymond Gosling in May 1952. It was the clearest image of DNA's helical structure ever produced at that point. When Watson saw it — shown by Wilkins without Franklin's knowledge — he immediately recognized its significance. He later admitted it was decisive for solving the structure.
Franklin died of ovarian cancer on April 16, 1958, aged 37. The Nobel was awarded in 1962 to Watson, Crick, and Wilkins. Nobel Prizes are not awarded posthumously, so Franklin was ineligible. Whether she would have been included had she lived remains one of science history's most debated counterfactuals.
Photo 51 and Franklin's MRC report data were shared with Watson and Crick without her knowledge or consent. Watson saw Photo 51 in January 1953; the double helix paper was published in April 1953. Most historians of science conclude that without access to her data, Watson and Crick could not have solved the structure when they did.
Franklin used X-ray crystallography to establish that DNA exists in two forms (A and B), that the phosphate backbone is on the outside of the helix, and that the molecule has a helical structure with precise dimensions. This was the decisive empirical foundation upon which Watson and Crick built their model.