59 points pavel_lishin 2 days ago 33 comments
dekhn 2 days ago | parent
That's the first actual evidence I've seen (I am a DNA nerd and have been trying to understand what her contribution to the intellectual discovery of DNA's double-helix antiparalel).
I would need to go back to Judson's book (Eighth Day of Creation) and see if he actually missed this.
dnautics 2 days ago | parent
FTA:
The new paper does not challenge Watson and Crick’s achievement. Their model of DNA, rushed out in a brief article in Nature after Watson caught his glimpse of photograph 51, went well beyond Franklin’s understanding. [Watson and Crick's model's] two strands running in opposite directions and zipperlike arrangement of complementary base pairs explained how the molecule could carry genetic information and be copied each time a cell divides. “The fact that it was a helix, you know, was not the most exciting aspect of this structure,” says Soraya de Chadarevian, a science historian at the University of California, Los Angeles. Indeed, by 1952, other researchers striving to make sense of the molecule also suspected it was helical. [for example Pauling, who at one point thought DNA might be an alpha helix-like structure]
dekhn 2 days ago | parent
Instead, this new paper and several previous papers based on Franklin's notes:
https://link.springer.com/article/10.1007/s10739-026-09866-7 (the paper referenced in the article) -> Franklin's notes say "“evidence for [a] 2-chain […] helix.”Footnote21" where Footnote 21 is Notebook entry for 10 February 1953 (FRKN 1/1, Franklin Papers). The images of her notes are here: https://www.jessiemillsauthor.com/journalism/photo-49-the-x-... (I can't read her handwriting, so I'm taking the 2-chain helix on faith. Also, this article https://philpapers.org/archive/NIETNC-3.pdf interprets her notes to say she recognized the complementary bases: " Franklin’s notebook entry of January 19, 1953—“diads in A. Chargaff data” (Klug index, FRKN 1/1, p. 3)—demonstrates that she had inferred complementary base pairing from the conjunction of Chargaff’s ratios and the crystallographic dyad symmetry, eleven days before Watson saw Photo 51.
So based on the above interpretation, I would probably update my understanding from:
1) Gosling collected the fibre diffraction data and Franklin recognized both that it was a helix, and that the bases were on the inside and complementary. 2) Watson and Crick deduced that DNA formed a double helix with antiparallel chains.
And now I would update it to: 1) Gosling collected the fibre diffraction data and Franklin recognized both that it was a double helix, and that the bases were on the inside and complementary. At that point I think she would have recognized the chains were antiparallel due to dyad symmetry, right?) 2) Watson and Crick deduced that DNA formed a double helix with antiparallel chains.
That's the key bit- I had not previously seen any evidence that Franklin knew it was a double helix or that she knew about the complementary bases. And since this is an area that generates a lot of strong emotions, and there's a lot of noise, I'd like to see her exact text, but I simply cannot read her handwriting.
masfuerte 3 hours ago | parent
> Evidence for 2-chain (or 1-chain helix)?
> 49c - general trend is as for single containing helix
> (which differs from single * chain in integral no. residues/*
> only in contribn of high order J'n to the latter)
The crossed out bit says:
> and this is indistinguishable from double helix with residues on
> each having same ζ-value, since 2nd chain has opposite signs in
> ξ & η terms (eq 1 - 2), and eqn 2 contains only [...]
She was certainly thinking about double helixes.
Teever 2 days ago | parent
As for base complementarity it seems likely that she would have made that leap from everything else that she knew of at the time, but I'm no expert on this subject and have not read her notes.
titanomachy 1 hour ago | parent
> It is easy to feel great sympathy with Franklin. The fact remains that she never made the inductive leap... before she learned about the model proposed by Watson and Crick, she and Gosling began to draft a paper to state their conclusions so far about the B structure. That draft also survived among Franklin’s papers. It was vigorous, clear, and limited. Klug and I went over it one afternoon in his office. “You see, she was lacking one final step,” Klug said. “Well, two steps. What she missed was the presence of the dyad—the symmetry of the molecule. Which Francis had seen immediately from her information about the space group. And even though her notes earlier showed that she knew about Chargaff’s ratios, she never got to the base pairing.”
Seems like Judson accepts Klug's version of the story: she understood that the structure was helical, but not that it was doubled or base-pair. There's also a final essay at the end of the book "In defence of Rosalind Franklin" which basically reiterates this:
"She had not perceived that the backbones run in opposite directions. She had not started modelling the B form as a double helix and so had yet even to encounter the problem of fitting the bases inside."
philipallstar 2 days ago | parent
It was Watson and Crick who discovered the double helix, even if Franklin did write something down about a single helix from a previous photo that they didn't read.
dnautics 2 days ago | parent
She might have measured those parameters, but she still didn't know what she had (as evidenced by how she subsequently spent a ton of time on Z-dna)
dekhn 2 days ago | parent
dnautics 1 day ago | parent
bondarchuk 4 hours ago | parent
(edit: should note the HN submission title (at present "Despite what Watson said, Rosalind Franklin understood structure of DNA first") does not actually occur in TFA)
burnte 4 hours ago | parent
gumby 3 hours ago | parent
dang 2 hours ago | parent
Edit: Since https://news.ycombinator.com/item?id=49969073 was posted earlier and the comments there were more substantive, I've merged the thread thither and re-upped that one.
I have also re-upped 2 other excellent submissions you made - thank you!
scythe 3 hours ago | parent
https://en.wikipedia.org/wiki/History_of_molecular_biology#D...
>In 1948, [Linus] Pauling discovered that many proteins included helical (see alpha helix) shapes. Pauling had deduced this structure from X-ray patterns and from attempts to physically model the structures. (Pauling was also later to suggest an incorrect three chain helical DNA structure based on Astbury's data.) Even in the initial diffraction data from DNA by Maurice Wilkins, it was evident that the structure involved helices.
https://en.wikipedia.org/wiki/DNA#History
>Franklin told Crick and Watson that the [phosphate] backbones had to be on the outside. Before then, Linus Pauling, and Watson and Crick, had erroneous models with the chains inside and the bases pointing outwards.
The mere idea of a helix is not especially complex and could have existed in the minds of many theorists at the time. Franklin's discovery provided the final piece of the puzzle, but the desire to attribute major scientific discoveries to a single author or team is based on an incorrect interpretation of the scientific process. The real reason that Franklin didn't win the Nobel Prize is because she died:
>In 1962, after Franklin's death, Watson, Crick, and Wilkins jointly received the Nobel Prize in Physiology or Medicine.[210] Nobel Prizes are awarded only to living recipients. A debate continues about who should receive credit for the discovery.
A student of Franklin, Raymond Gosling, actually took Photo 51. He was not awarded the Prize.
bonsai_spool 1 hour ago | parent
Yes, how many students get Nobel prizes for the work of their graduate advisor that they didn’t go on to examine independently?
lacker 3 hours ago | parent
https://www.nature.com/articles/d41586-023-01313-5
It seems like there are several different parts to the discovery of the "structure of DNA" and different people contributed.
1. DNA is helical
2. DNA is a double helix
3. The ACGT copying mechanism
Part 1 was Franklin and Wilkins. Part 3 was Watson and Crick. Part 2 is the part under debate, to what degree was the double helix clear from just Franklin's imaging?
But really, how much does it matter? It seems like the four of them each contributed a lot. The Nobel prize only went to the other three, in large part because Franklin died before it was given out.
underlipton 28 minutes ago | parent
Watson's shadow would not extend so far if Franklin's role were known - not just because it would have diminished his, but also because her presence would have undermined attitudes that marginalized non-white-men, in the field of science and beyond. It matters a great deal, unfortunately. And it's a tough pill to swallow for a lot of people who have their pride wrapped up in what he represents.
hungryhobbit 3 hours ago | parent
But, when some male jerk tries to claim they invented X or discovered X, but really a woman did so (something that is not unique to here: https://en.wikipedia.org/wiki/Matilda_effect) it's good for people to correct the mistake and properly attribute the person who really made the discovery/invention.
tyjen 1 hour ago | parent