February 28th · 1953 · Science & Technology
The Secret of Life: Cracking the Structure of DNA
On 28 February 1953, James Watson and Francis Crick worked out the double-helix structure of DNA at Cambridge, revealing how living things copy and pass on their genetic information.
According to James Watson’s own account, Francis Crick walked into a Cambridge pub at lunchtime on 28 February 1953 and announced that the two of them had “found the secret of life.” Whether or not the line was delivered quite so theatrically, the claim was essentially true.
The molecule everyone was chasing
By the early 1950s it was widely accepted that DNA carried the genetic instructions of living things, but no one knew how a single kind of molecule could store information and copy itself. Several groups were racing to solve its structure, including Linus Pauling in California and the team of Rosalind Franklin and Maurice Wilkins at King’s College London. [1]
The double helix
Working with cardboard and metal models at the Cavendish Laboratory, Watson and Crick arrived at the answer: two strands winding around each other in a double helix, held together by paired bases on the inside. [2] The crucial insight was base pairing — adenine always pairs with thymine, and guanine with cytosine. That rule meant the two strands were complementary: each could serve as a template to reconstruct the other.
Standing on Franklin’s data
The model depended heavily on experimental evidence the pair did not generate themselves. Rosalind Franklin’s X-ray diffraction images — especially the famous “Photograph 51” — and her measurements were instrumental, and were shown to Watson without her knowledge. [1] Her contribution went largely unrecognized for decades.
”It has not escaped our notice”
Watson and Crick published their model in Nature on 25 April 1953 in a paper barely a page long, closing with one of the most understated sentences in the history of science: “It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material.” [2] Watson, Crick, and Wilkins shared the Nobel Prize in 1962; Franklin had died in 1958 and was not eligible.