How did Rosalind Franklin miss the helix in her iconic DNA image? She didn't

If I read Franklin's notes this establishes that she did in fact conceive of a double helix and base complementarity in the center (I can't see if she also recognized it was antiparallel).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. reply: I happen to be reading Judson right now. Quoting from it here:> 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....

I think this is a better article on the topic:https://www.nature.com/articles/d41586-023-01313-5It seems like there are several different parts to the discovery of the "structure of DNA" and different people contributed.1. DNA is helical2. DNA is a double helix3. The ACGT copying mechanismPart 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. reply: > 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.A Nobel can only be split among 3. Agree with the rest of your post.

Clickbait headline which misframes the controversy, to nobody's benefit.Helical DNA was the strongest candidate by 51, in part because earlier and cruder X-ray diffraction images had existed for some time (10+ years) and were suggestive of this structure. All of the scientists in question, and many others, collaborated on that possibility at that time, and long before 'Photo 51'. It was not a surprise, but rather the focus of their work.Franklin was making the famous improved images with the explicit intent of revealing or disproving the helical structure. She and her lab produced the most definitive evidence for helical B-DNA (Photo 51) in early 52, but during 52 the conclusion was still a matter of debate (and humor) amongst them - in particular Franklin was not convinced that A-DNA was helical. From Wiki:> In July 1952, as a practical joke on Wilkins (who frequently expressed his view that both forms of DNA were helical), Franklin and Gosling produced a funeral notice regretting the 'death' of helical A-DNAThis left the molecular structure and number of strands as open questions. Triple helix models had been attempted by Pauling, Watson and Crick at that time....

> Science historian Alistair Sponsel of the Science History Institute and crystallographer Brian Sutton of KCL argue Franklin knew the earlier photo had revealed a helix—the epiphany Watson claimed for himself—and that is precisely why she made a second, more refined version, photograph 51.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.

So did Franklin provably realize the double-helix structure of DNA first or not? A lot of beating about the bush here but the article stops just short of actually explicitly making the claim it's working so hard to imply, AFAICT...(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) reply: It's hard to say because the helix existed as a theory before it could be verified. From Wikipedia: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....

what? she was doing a form of crystallography that ONLY makes sense if it's a helix? Like, any time you are doing fiber diffraction it's pretty much "a helix". Who claimed she didn't realize it was a helix? I thought the claim was that she didn't recognize the significance of the helical parameters, which of course she couldn't, she wasn't a chemist and didn't have a model in mind with knowable parameters.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) reply: I beleive fibre diffraction also works on parallel fibres (non-helical). For example, long chains of beta-sheet (look at beta keratin, which is one of the early non-helical structures analyzed by Astbury).

This is not a case where she was running to the scientific society saying “double helix!” and they told her to get lost. She was sitting on evidence. We’ll never know how long it would have taken her to figure out its meaning, but we know Watson was first to recognize it out loud.If any of you have time, I’ll tell you how I invented Twitter, Reddit, and AI assistants.

dupe, see older post here: https://news.ycombinator.com/item?id=49998006

Related: https://www.nature.com/articles/d41586-023-01313-5

Why does attributing any bit of mankind's progress to a specific individual matter? It matters because history is really boring if it's just about groups: we humans love individual human stories.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.