A new study of Rosalind Franklin’s papers and photographs suggests she understood DNA’s double-helix structure before James Watson and Francis Crick published it. The research, published Monday in the Journal of the History of Biology, examines the famous Photograph 51 and finds that Franklin deliberately prepared it for publication, not as an experimental shot.
The Photograph That Changed Everything
Photograph 51 was taken in May 1952 and later published to show the double-helix structure. Live Science’s study reveals it was a new exposure of a sample Franklin had already photographed. She started Photograph 51 the same day she saw Photograph 49, her first picture of the sample.
“She took it because she wanted to get a really refined version,” said study co-author Alistair Sponsel, a historian of science at the Science History Institute in Philadelphia. He added that the effort to improve the image “is a sign she knew she had something really important on her hands.”
What Watson Saw
Franklin’s photographs were central to the discovery. In his 1968 autobiography “The Double Helix: A Personal Account of the Discovery of the Structure of DNA,” Watson wrote that seeing Photograph 51 was his “aha” moment. “The black cross of reflections which dominated the picture could only arise from a helical structure,” he wrote.
The Two Structures
Franklin’s notes reveal she noted the possible helical shape in her first picture of the sample, Photograph 49. In her mind, Sponsel said, the two images served different purposes. Photograph 49 was the experimental image revealing new data. Photograph 51 was the polished image meant to convey those findings clearly.
Why She Didn’t Publish
Sponsel and Brian Sutton, a molecular biophysicist at King’s College London, think Franklin’s notes explain why she delayed publication. Her February 1952 report laid out her goal: to understand the two forms of DNA, then known as A and B.
| Date | Event |
|---|---|
| February 1952 | Franklin writes report laying out goal to study DNA’s two forms |
| May 1952 | Photograph 51 taken |
| 1962 | Watson, Crick and Wilkins share Nobel Prize |
Structure B, shown in Photographs 49 and 51, turned out to be the natural double helix. Structure A is the form DNA takes when dehydrated in the lab. Photograph A appeared richer with data, so Franklin decided to study that first.
How the Scoop Happened
While she worked, Maurice Wilkins showed Watson her photographs of structure B. Together with Crick, they built a model of DNA’s double helix. Franklin died of ovarian cancer in 1958, making her ineligible for the Nobel Prize.
The Archive Behind the Study
The project began when the Science History Institute acquired a new collection of Franklin’s material, including work by her graduate student Raymond Gosling. Sponsel and Sutton also reviewed archives at King’s College London, where Franklin worked when she took the photos.
What the Study Changes
The new research challenges the idea that Franklin missed a major discovery because she published little about Photograph 51. Instead, it suggests she recognized its significance and planned it carefully.
“In Franklin’s mind, they were two different types of scientific image.”
The Record Now Stands
The study adds to the record of Franklin’s contributions. Her photographs were the foundation of the 1962 Nobel Prize in Medicine, awarded to Watson, Crick and Wilkins. The prize excluded her entirely.
The new work, published as “Photograph 49 is the Key to Understanding the History of Rosalind Franklin’s DNA Photograph 51,” offers a fresh look at what Franklin actually knew and recorded.
Source material: “'She knew she had something really important on her hands': Rosalind Franklin figured out DNA's helical structure before Watson and Crick, study suggests,” Live Science.
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