Rosalind Franklin and Photograph 51. Credit: King’s College London Archives
Just a couple weeks ago, on April 25, scientists around the U.S. celebrated National DNA Day, an annual celebration recognizing the anniversary of scientists publishing the double helix structure of DNA for the first time in Nature. This year was extra special as 2023 commemorated both the 20th anniversary of the Human Genome Project’s completion and the 70th anniversary of the discovery of the DNA double helix.
Admiration and reverence for James Watson and Francis Crick as the fathers of DNA go hand-in-hand with April 25. Less often do we talk about Maurice Wilkins, a DNA researcher at King’s College London, who would later share the 1962 Nobel prize with Watson and Crick for the discovery of the molecular structure of DNA. And even less often do we talk about the fourth forgotten member of the DNA discovery team—Rosalind Franklin.
While she was not awarded the Nobel prize, we know that Franklin, a physical chemist, played a vital role in Watson and Crick’s ultimate discovery. Oral history says Watson made his big breakthrough after he was shown an X-ray image of DNA taken by Franklin—without her permission or knowledge. For this and many other reasons, Franklin has been portrayed as the “wronged heroine” in the DNA story, another female casualty of the male-dominated scientific industry.
But, new work by Matthew Cobb and Nathaniel Comfort at University of Manchester and Johns Hopkins University, respectively, argues the assumed perspective is not really how the events unfolded. In a commentary in Nature, the professors say they found an unstudied draft news article from 1953 meant for Time magazine that tells a different story. While visiting Franklin’s archive at Churchill College in the UK, the professors—who are separately writing biographies on Watson and Crick—also went through her notes, reconstructing the timeline and development of her ideas.
“Together, these documents suggest a different account of the discovery of the double helix. Franklin did not fail to grasp the structure of DNA. She was an equal contributor to solving it,” they write in Nature. “Getting Franklin’s story right is crucial because she has become a role model for women going into science. She was up against not just the routine sexism of the day, but also more subtle forms embedded in science—some of which are still present today.”
Early DNA ideas
In the early 1950s, the structure and function of DNA remained unclear. It had been found in every cell type investigated, and was known to consist of a phosphate backbone to which were attached four kinds of base—adenine, thymine, cytosine and guanine (A, T, C and G).
In 1951, Franklin joined Wilkins at King’s College London as an expert on using X-ray diffraction to study the structure of molecules, including potentially DNA. But, the two quickly clashed, stalling their collaboration, but not their similar research interests.
Franklin was quickly able to exploit a discovery that Wilkins had made earlier—DNA in solution could take two forms, what she called the crystalline or A form, and the paracrystalline, or B form. That same year, Franklin gave a seminar where she described both A and B collectively as “big helix with several chains, phosphates on outside, phosphate–phosphate interhelical bonds, disrupted by water.” However, unable to resolve the A-form structure, Franklin decided by the middle of 1952 that it was not actually helical.
Photograph 51
According to Watson, in early 1953, he visited King’s and got into an argument with Franklin. Wilkins, he wrote, rescued him from the confrontation and then showed him Photograph 51, a particularly clear image of the B form, taken 8 months earlier by Franklin and her graduate student. Watson says this is the image that told him a DNA helix must exist as only that structure could produce the marks clearly seen in the image.
“But Watson’s narrative contains an absurd presumption,” Cobb and Comfort write in their new commentary. “It implies that Franklin, the skilled chemist, could not understand her own data, whereas he, a crystallographic novice, apprehended it immediately.”
The two professors/biographers suggest it was not the photograph that led Watson to his breakthrough, but other measurements and data from Franklin and Wilkins in the duo’s Medical Research Council (MRC) report.
As Cobb and Comfort rehash, shortly after Watson saw Photograph 51, Crick’s supervisor, Max Perutz, handed them an informal report of the activity of the Franklin and Wilkin’s MRC unit, which Perutz had been given as part of an official visit to the unit in December 1952. This included a page from Franklin, describing her work. The letter was not confidential, but questions still remain on whether it was meant to be shared with Watson and Crick,
In her contribution to the MRC report, Franklin confirmed the 34 Å result for the B form. She also reported that the unit cell of DNA was huge. Franklin added some key crystallographic data for the A form, indicating that it had a “C2” symmetry, which in turn implied that the molecule had an even number of sugar-phosphate strands running in opposite directions.
“Notes by Crick for a lecture on the history of the double helix, given to historians of science at the University of Oxford in May 1961, together with formal and informal remarks made throughout his life, reveal that, unlike Photograph 51, this report was truly significant for confirming the structure that Watson and Crick eventually obtained,” write Cobb and Comfort. “In the end, neither Photograph 51 nor the MRC report ‘gave’ Watson and Crick the double helix. What did was six weeks of what they later described as trial and error—making chemical calculations and fiddling about with cardboard models.”
In a full description of DNA’s structure in a paper submitted in August 1953 and published in 1954, Crick and Watson acknowledged that their conclusions would have been “unlikely if not impossible” without the MRC report.
A missing piece of TIME
Three weeks after the DNA papers were published in Nature, they caught the attention of Joan Bruce, a London journalist working for Time. In the draft news article that Cobb and Comfort recently discovered, Bruce portrayed the DNA research as being done by two teams—one consisting of Wilkins and Franklin gathering experimental evidence using X-ray analysis; and the second comprising Watson and Crick working on theory.
To a certain extent, wrote Bruce, the teams worked independently, although “they linked up, confirming each other’s work from time to time, or wrestling over a common problem”. The professors point to two specific examples of Franklin’s work that they say “render [her] in a position of strength, every bit a peer of Wilkins, Crick and Watson.”
“[This] strengthens our case that Franklin was an equal member in a group of four scientists working on the structure of DNA. She was recognized by her colleagues as such, although that acknowledgement was both belated and understated,” write Cobb and Comfort.
Ultimately, Bruce’s article was scraped as it needed a lot of revisions to ger the science correct. Still, even as a draft, the article portrays franklin as a valued member of the four-person DNA team.
“It is tantalizing to think how people might remember the double-helix story had Bruce’s article been published, suitably scientifically corrected. From the outset, Franklin would have been represented as an equal member of a quartet who solved the double helix, one half of the team that articulated the scientific question, took important early steps toward a solution, provided crucial data and verified the result,” conclude Cobb and Comfort.