Mark ở vũ trụ khác · Another Universe Genes and Rare Diseases #1 · DNA structure · History of science

Photo 51

Franklin & Gosling, Watson & Crick, Wilkins · Nature 171 · 25 April 1953

The storywho really helped find the double helix of DNA
FindingDNA is two twisted strands, A pairs with T, G with C
The photo"Photo 51", taken in May 1952 at King's College London
LabelSolid on the structure; the familiar story needs fixing

Source: Watson and Crick (1953), Nature 171: 737–738; Franklin and Gosling (1953), Nature 171, same issue; King's College London, "The story behind Photograph 51" (date taken).

For reading and understanding, not a substitute for medical advice.

One-minute recap

Essence

An X-shaped photoIn May 1952 Rosalind Franklin's group X-rayed DNA. The X pattern is the signature of a helix.
Data took a detourThe photo and a report with Franklin's measurements reached Watson and Crick without anyone asking her first.
Double helix, A with T, G with COn 25 April 1953 Nature ran three papers in one issue. Watson and Crick's model explained how DNA copies itself.
A quartet, not a duoIn 2023 Cobb and Comfort reread the archives: Franklin was an equal contributor, not a "robbed victim".
From structure to the clinicIf DNA is a string of letters, wrong letters can be read. In 2021, genome sequencing diagnosed 1 in 4 rare-disease patients in an English project.

Source: King's College London (date of the photo); NLM Profiles in Science, Francis Crick Papers (MRC report); Watson and Crick (1953); Cobb and Comfort (2023), Nature 616: 657; Smedley et al. (2021), NEJM 385: 1868–1880 (25%).

Part 1

The question

Who found the double helix of DNA? The textbook answer is "Watson and Crick". The internet answer is "they stole Franklin's photo". The original archives tell a third story, truer than both.

Question and wording are Mark's, based on Cobb and Comfort (2023), Nature 616: 657.

1952MeasureFranklin and Gosling X-ray DNA in London.
→
1953Build a modelWatson and Crick in Cambridge combine the measurements with base pairing.
→
2023RetellOld papers show a quartet solving the problem together.
Part 2

The story

Who, where, when, and in what setting.

1869 · DNA is foundYoung Swiss physician Friedrich Miescher isolates a substance from cell nuclei and calls it "nuclein". DNA had a name long before; what nobody knew was its shape.
1951 · Franklin joins King's College LondonA 31-year-old physical chemist who specialised in X-raying crystals. In the same building was Maurice Wilkins, also working on DNA. The two did not get on.
May 1952 · Photo 51The camera was set up on 2 May and the film developed on 6 May. Raymond Gosling, Franklin's PhD student, photographed DNA fibres in the wet "B" form. The clearest X pattern anyone had seen.
15 Dec 1952 · A report takes a detourBritain's Medical Research Council (MRC) visited the lab. Its report included Franklin's unit-cell measurements. Max Perutz, a committee member, passed it to Watson and Crick in Cambridge. Franklin was not asked.
Jan 1953 · Wilkins shows Watson the photoFranklin was about to move to Birkbeck College and hand her DNA data back to the King's group. Wilkins showed Photo 51 to Watson without her knowledge.
10 Feb 1953 · Franklin was getting close tooHer notes consider that the B form might be a two-chain helix.
25 Apr 1953 · Three papers, one issue of NatureWatson and Crick propose the model. Next come Wilkins and colleagues, then Franklin and Gosling with Photo 51. Watson and Crick only thank the King's group for "unpublished experimental results".
16 Apr 1958 · Franklin diesOvarian cancer, aged 37. In her last years she worked on virus structure at Birkbeck with Aaron Klug.
1962 · The Nobel PrizeThe Physiology or Medicine prize goes to Crick, Watson and Wilkins.
1968 · A book changes the tellingWatson's The Double Helix frames seeing Photo 51 as a "eureka" moment and paints Franklin as difficult and unable to read her own data.

Source: Dahm (2005), Developmental Biology 278: 274–288 (Miescher 1869); King's College London and UKRI, "From the archive: Photo 51" (2 and 6 May 1952, Gosling, B form); NLM Profiles in Science, Francis Crick Papers (visit of 15 Dec 1952, Perutz); Berkeley "Understanding Science" (notes of 10 Feb 1953); King's College London (Wilkins showing the photo as Franklin prepared to leave); Watson and Crick (1953); Aaron Klug's Nobel autobiography, nobelprize.org (Birkbeck, viruses); History of Physics Group, Institute of Physics (date of death, age); nobelprize.org (1962 prize). Age in 1951 computed from birth year 1920 (secondary source). The clash with Wilkins and the 1968 book's portrayal follow Cobb and Comfort (2023).

Context: why did two groups 80 km apart share data?

The labs at King's (London) and the Cavendish (Cambridge) were both MRC-funded. Sharing internal reports between MRC groups was normal. The problem was that nobody asked Franklin.

A 1953 letter from a King's colleague to Crick suggests Franklin knew the MRC report data would reach Cambridge and did not object. So "stealing" is too strong; "used without due credit" is closer to the truth.

Source: Cobb and Comfort (2023), Nature 616: 657, via the University of Manchester press release and Chemistry World (secondary sources). The London–Cambridge distance is Mark's estimate.

Part 3

How genes work, in 3 sentences

1. DNA is two strands twisted round each other like a spiral ladder. Each rung is a pair of "letters": A always pairs with T, G always with C.

2. The order of the letters is the information. A gene is a stretch of letters the cell reads to make a protein.

3. When a cell divides, the strands separate and each serves as a template for a new one. A wrong letter is copied too, and many rare genetic diseases start from one wrong letter like that.

Source: Watson and Crick (1953) (A–T, G–C pairing, the copying hint); MedlinePlus Genetics, "What is DNA?" and "What is a gene?" (US National Library of Medicine).

Double helix diagram. Two strands wind round each other; rungs are A–T and G–C pairs. Rungs are 3.4 ångström apart; every 10 rungs make one full turn, 34 ångström. Right: the strands separate and each templates a new one. ATGCTACGATGC one turn = 10 rungs = 34 Å rungs 3.4 Å apart (1 Å = one ten-billionth of a metre) copying: split, then rebuild A G T Cold strand T C A Gnew strand built on it T C A Gold strand A G T Cnew strand built on it a wrong letter in the old strandgets copied into the new one
Biology's most famous understatement. The 1953 paper ends by saying the pairing they propose "immediately suggests a possible copying mechanism for the genetic material". Drawing not to scale.Source: Watson and Crick (1953), Nature 171: 737–738 (3.4 Å spacing, repeat after 10 residues, i.e. 34 Å; quoted sentence); checked against teaching material from Newcastle University and the Max Planck Institute Heidelberg, full text not opened.
Three pieces that made the model. Piece 1: Photo 51's X pattern shows DNA is a helix. Piece 2: the MRC report's unit-cell measurements show the two strands run in opposite directions. Piece 3: Chargaff's rule and A–T, G–C pairing. Together: the double helix. 1 · Photo 51 (King's) X shape: DNA is helical 2 · MRC report strands run opposite 3 · Pairing (Cambridge) A = T G ≡ C fits, explains Chargaff double helix model, 25 Apr 1953
No piece was enough on its own. Photo 51 says DNA is helical, not how many strands. Crick later said the unit-cell dimensions in the MRC report were essential to see that the two strands run in opposite directions.Source: NLM Profiles in Science, Francis Crick Papers (MRC report, Crick's 1959 lecture notes); KCL and UKRI (Photo 51); Watson and Crick (1953) (pairing). Chargaff's rule: amounts of A equal T, G equal C.
Part 4

Fact check: facts and myths

12 things often said about Photo 51, checked against the archives and the original papers. Tap a row for the reason.

SOLIDPhoto 51 was taken in May 1952 at King's College by Gosling, in Franklin's group

Camera set 2 May, film developed 6 May 1952 (King's College London; UKRI). Sources differ on whether "51" counts Franklin's or Gosling's photos.

SOLIDWilkins showed Watson Photo 51 in January 1953 without Franklin knowing

King's College London; Berkeley "Understanding Science". Some secondary sources give 30 January 1953.

SOLIDThe MRC report with Franklin's measurements reached Watson and Crick via Max Perutz

Visit on 15 December 1952; Perutz sat on the committee (NLM Profiles in Science, Francis Crick Papers).

SOLIDThree DNA structure papers appeared in one issue of Nature on 25 April 1953

Watson and Crick (pp. 737–738), Wilkins, Stokes and Wilson (pp. 738–740), Franklin and Gosling, Nature 171 no. 4356.

SOLIDA–T, G–C pairing immediately suggests how DNA copies itself

Watson and Crick's closing sentence (1953). Later experiments confirmed each strand templates a new one.

SOLIDThe 1962 Nobel Prize in Physiology or Medicine went to Crick, Watson and Wilkins

"For their discoveries concerning the molecular structure of nucleic acids and its significance for information transfer in living material" (nobelprize.org).

CAUTION"Watson and Crick stole Photo 51"

The data reached them without Franklin being asked. But a 1953 letter suggests she knew the MRC data would be shared. Cobb and Comfort (2023) call it a collaboration told wrongly, not a theft.

CAUTION"Franklin missed the Nobel only because she was a woman"

She died in 1958; the prize came in 1962. Under the rules then, a prize went to someone who had died only if they had been nominated while alive (PRI and Nature blogs, 2011, secondary). Bias against women scientists was real, but it cannot explain the Nobel on its own.

CAUTION"X-rays definitely caused Franklin's cancer"

A popular hypothesis, never proven. Some point to a possible inherited family risk. No test exists to settle it (Time, Jewish News, secondary).

FALSE"DNA was discovered in 1953"

1953 is when its shape was found. Friedrich Miescher isolated DNA in 1869 (Dahm 2005).

FALSE"One look at Photo 51 and Watson saw the double helix"

The photo shows a helix, not whether there are two or three strands. The MRC measurements and base pairing decided it. Cobb and Comfort call the 1968 "eureka" moment a literary device.

FALSE"Franklin did not understand her own data"

Her notes of 10 February 1953 consider a two-chain helix. A 1953 draft article for Time magazine, written in consultation with her, described the King's and Cambridge groups as two halves solving one problem (Cobb and Comfort 2023).

Source: as noted in each row; full list in Part 9.

Part 5

Where we are today

From a twisted ladder to the genetics lab.

1954 · Watson and Crick say it themselvesIn a longer paper they wrote that without the King's data, building the model would have been "most unlikely, if not impossible".
1958–1982 · A legacy in virusesAfter Franklin's death Aaron Klug led the group on virus structure. Klug won the 1982 Nobel Prize in Chemistry.
2021 · Reading DNA to find rare diseasesEngland's 100,000 Genomes pilot: 4,660 people from 2,183 families, 161 rare diseases. Whole-genome sequencing gave a diagnosis to 25% of patients; 35% for disorders likely caused by one gene, only 11% for complex ones.
Apr 2023 · Retelling the storyExactly 70 years on, Cobb and Comfort wrote in Nature that Franklin was "an equal member of a quartet" that solved the double helix.
6 Nov 2025 · The last of them diesJames Watson died aged 97. In 2019 Cold Spring Harbor Laboratory had cut all ties with him over racist remarks.

Source: Crick and Watson (1954), Proceedings of the Royal Society A, quote via ScienceAlert 2023 (secondary); Aaron Klug's Nobel autobiography, nobelprize.org; Smedley et al. (2021), NEJM 385(20): 1868–1880; Cobb and Comfort (2023), Nature 616: 657; NPR, Scientific American, Chemistry World Nov 2025 (secondary).

Share of rare-disease patients diagnosed by whole-genome sequencing in the 100,000 Genomes pilot: overall 25%; disorders likely caused by one gene 35%; complex disorders 11%. diagnosed by reading the whole genome (England, 2021) overall, all patients25% likely single-gene disorder35% complex, many factors11%
Reading the letters does not always find the error. Three quarters of patients in the project still had no diagnosis. Single-gene diseases are far easier to pin down than diseases of many genes plus environment, the topic of piece #2.Source: Smedley et al. (2021), "100,000 Genomes Pilot on Rare-Disease Diagnosis in Health Care", NEJM 385(20): 1868–1880.
Part 6

Verdict

Scores are Mark's assessment based on the sources in Part 9, not figures from a study.

Soundness of the model
5/5
Impact on medicine
5/5
Fair credit (in 1953)
2/5
Popular story matches facts
2/5
Worth remembering
  • The model was right and explained heredity at once
  • Three groups, two cities, one result
  • The foundation of today's genetic testing
Needs correcting
  • Data used without asking the person who made it
  • The 1953 paper credited Franklin too faintly
  • The 1968 book built a "eureka" myth

Label: SOLID on the science. The story deserves retelling: not two geniuses and a victim, but four people solving one problem.

More: why doesn't Mark label the "theft" story False?

Because two things are true at once: the data reached Watson and Crick without anyone asking Franklin, and Franklin herself knew the MRC data would be shared. "Theft" overstates it; "nothing happened" understates it. Caution is the honest label.

The "More" box is Mark's comment, based on sourced facts in Parts 2 to 5.

Part 7

Lesson: ask "whose data is this, and how was it measured?"

The Photo 51 story teaches a habit that works even when you hold a test report.

For reading and understanding, not a substitute for medical advice.

Four habits: ask who measured; doubt the eureka moment; read genetic results on five levels; ask your doctor three questions. 1 · who measured?find the originnot just the teller 2 · doubt "eureka"discovery is assemblyask "who else helped?" 3 · read gene results5 levels, not 2"uncertain" ≠ "disease" 4 · ask the doctor3 questionssee cards below Franklin measured, Watson and Crick assembled. Know who did what to read results right.
Each habit rests on a sourced fact. Genetic test reports usually place a variant in one of 5 levels: pathogenic, likely pathogenic, uncertain significance, likely benign, benign.Source: Richards et al. (2015), ACMG and AMP guideline, Genetics in Medicine 17(5): 405–424 (5 levels); the habits are Mark's suggestions.
Ask who measuredWhen you see a number, find who produced it: which lab, which method, which year.
Doubt the "eureka""One person looked and understood" stories often leave out the people who did the measuring.
Read "uncertain" correctly"Variant of uncertain significance" means science lacks data, not "you have the disease".
Three questions for the doctorWhich part of my genes did the test read? Which level is this result? Should relatives be tested?
Self-check: read a "discovery" headline in 5 minutes

1. Pick a science news story you just read online.

2. Underline the names mentioned. Find the original paper: how many authors? Who ran the experiments, who analysed?

3. Does the story feature a sudden "it all clicked" moment? If so, find who did the measuring before it.

4. If it is about a gene that "causes disease", check which of the 5 levels the source gives.

The self-check is Mark's suggestion, not a study protocol.

Part 8

Read next

Cobb and Comfort (2023), "What Rosalind Franklin truly contributed to the discovery of DNA's structure"Nature 616. Short, a 15-minute read, with archival images.
Brenda Maddox (2002), Rosalind Franklin: The Dark Lady of DNAThe fullest biography. Read alongside Watson's The Double Helix (1968) to see both tellings.
MedlinePlus Genetics, "Help Me Understand Genetics"Free material from the US National Library of Medicine explaining DNA, genes and mutations in plain words.
Genes and Rare Diseases #02: There is no "intelligence gene"Why are rare diseases often caused by one gene, while height or intelligence come from thousands of small ones?
Part 9

Sources

Main sources are the original papers in Nature and NEJM and science archives. The working environment blocks nature.com, PubMed and nobelprize.org, so figures were checked against those pages' own excerpts in search results (looked up 16 Oct 2026), without opening full texts. Secondary sources are marked.

  1. Watson JD, Crick FHC (1953), "Molecular Structure of Nucleic Acids: A Structure for Deoxyribose Nucleic Acid", Nature 171(4356): 737–738. nature.com
  2. Wilkins MHF, Stokes AR, Wilson HR (1953), "Molecular Structure of Nucleic Acids: Molecular Structure of Deoxypentose Nucleic Acids", Nature 171: 738–740.
  3. Franklin RE, Gosling RG (1953), "Molecular Configuration in Sodium Thymonucleate", Nature 171 (same issue 4356, with Photo 51).
  4. Cobb M, Comfort N (2023), "What Rosalind Franklin truly contributed to the discovery of DNA's structure", Nature 616: 657.
  5. Smedley D et al. (2021), "100,000 Genomes Pilot on Rare-Disease Diagnosis in Health Care – Preliminary Report", NEJM 385(20): 1868–1880.
  6. Richards S et al. (2015), "Standards and guidelines for the interpretation of sequence variants", Genetics in Medicine 17(5): 405–424.
  7. Dahm R (2005), "Friedrich Miescher and the discovery of DNA", Developmental Biology 278(2): 274–288.
  8. nobelprize.org, The Nobel Prize in Physiology or Medicine 1962; Aaron Klug's autobiography (Chemistry 1982). nobelprize.org
  9. US National Library of Medicine (NLM), Profiles in Science, Francis Crick Papers, section on DNA structure (MRC report 1952). profiles.nlm.nih.gov
  10. MedlinePlus Genetics, "What is DNA?", "What is a gene?". medlineplus.gov
  11. King's College London, "The story behind Photograph 51"; UKRI, "From the archive: Rosalind Franklin's famous Photo 51". kcl.ac.uk
  12. University of California Museum of Paleontology, Understanding Science, "The structure of DNA: cooperation and competition" (notes of 10 Feb 1953). undsci.berkeley.edu
  13. Secondary sources: University of Manchester press release and Chemistry World, Apr 2023 (Time draft, 1953 letter); ScienceAlert 2023 (Crick and Watson 1954 quote); History of Physics Group, Institute of Physics (date of death, age); PRI and Nature blogs, Oct 2011 (Nobel rule on posthumous awards); Time, Jewish News (cancer hypotheses); NPR, Scientific American, Chemistry World, Nov 2025 (Watson's death).