Watson and Crick's Discovery of DNA Structure Explained

Introduction: An Unlikely Discovery

The fact that James Watson and Francis Crick were able to discover the structure of DNA is, in retrospect, somewhat shocking. By the early 1950s, it had become clear that the riddle of DNA's structure would be solved through X-ray crystallography, while Watson admits in the fourth chapter of The Double Helix that "I knew nothing about the X-ray diffraction techniques that dominated structural analysis" (Watson 31). Moreover, some of the best scientists who did have a knowledge of X-ray crystallography — like Linus Pauling in America and Rosalind Franklin in the UK — were consciously working on the structure of DNA at the same time that Watson and Crick became involved.

Additionally, Watson was extraordinarily young at the time of the discovery. Although Crick was "thirty-five, yet almost totally unknown" at the time of their collaboration (Watson 7), Watson was born in 1928 and was in his early twenties while working on the structure of DNA. Watson was thus eight years younger than Rosalind Franklin, twelve years younger than Crick or Maurice Wilkins, and almost thirty years younger than Linus Pauling. Finally, Watson's scientific background before his arrival in England had been in zoology rather than chemistry, making it seem utterly unlikely that he would solve a problem involving chemical structure. Nevertheless, the account given by Watson in The Double Helix goes a long way toward demonstrating how this unlikely duo managed to discover the structure of DNA.

Social and Cultural Factors in the Scientific Race

A large part of the discovery was due to non-scientific factors — particularly the social and cultural traditions that can affect the pursuit of science, but which in this case were overcome, often by the sheer force of Watson's personality. Watson emphasizes the most distinctive aspect of the social environment of England in the second chapter of The Double Helix, by way of explaining why Crick had not concentrated on the structure of DNA before Watson's arrival: "it would have looked very bad if Francis had jumped in on a problem" that had already been under study by Maurice Wilkins (Watson 15). Watson specifies that this problem was specific to England, where "it simply would not look right," and it would not have arisen in France "where fair play obviously did not exist," nor in America, where different researchers would be at different institutions and thus engaged in competition (Watson 15–16).

Watson's own account in The Double Helix emphasizes competitiveness and casts the discovery of DNA almost as a race in which Watson and Crick managed to beat out competitors like Pauling, Wilkins, and Franklin. However, it is crucial to note that Watson was also taking advantage of a long-standing scientific tradition in which it is customary for a scientist to share research with others working on the same problems. As The Double Helix makes clear, Watson and Crick would have been utterly unable to determine the correct structure without access to Rosalind Franklin's research. Moreover, as Watson describes in the twenty-third chapter, he gained access to Franklin's photographs not through Franklin herself but through Wilkins — a move that violates this scientific etiquette of research sharing. Watson rather outrageously suggests in that chapter that he obtained access to the photograph of the B-structure because his own conflicts with Franklin allowed him to bond with Wilkins over the "emotional hell he had faced during the past two years" while working with her (Watson 167). It was precisely these traditions of scientific etiquette — regarding not impinging on another person's research area and regarding the ethics of sharing research — that Watson and Crick had to finesse in order to make their discovery.

Borrowed Methods and the Modeling Approach

In terms of how Watson and Crick actually arrived at their discovery, it is clear that the traditional pattern of scientific inquiry was not closely followed in their quest for DNA's structure. The necessary empirical research for explaining the structure of DNA had largely been done by others: the chief field of empirical research required was X-ray crystallography, about which Watson admits he was almost completely ignorant, but which was the focus of Wilkins's and Franklin's laboratory work. The inclusion of Wilkins when the Nobel Prize was awarded is presumably a recognition that Watson and Crick could not have arrived at their conclusions without the photographic evidence of crystallography they obtained through him. Franklin was, of course, dead by the time of the Nobel Prize award, so whether she would have been a more fitting third recipient than Wilkins is ultimately a moot point.

Moreover, the theoretical approach that Watson and Crick brought to their analysis was also largely borrowed. Watson admits that they were following the example of Linus Pauling, who had the reputation at the time for being the greatest chemist then alive. Watson emphasizes in The Double Helix that, while Pauling was capable of understanding the findings in X-ray crystallographic photographs and deducing what they suggested about molecular structure, his major breakthrough in determining difficult structures of complex molecules — such as the alpha-helix structure of the peptide chain — was accomplished through the use of physical models. As Watson puts it, for Pauling's discovery "in place of pencil and paper, the main working tools were a set of molecular models superficially resembling the toys of preschool children" (Watson 50). In the seventh chapter of The Double Helix, Watson admits outright that the basic method for approaching the structure of DNA would be to "imitate Linus Pauling and beat him at his own game" (Watson 48). Watson also suggests that — despite her access to the best relevant empirical data — Franklin's inability to perceive the structure first was due to her unwillingness to try this approach, viewing it as beneath her dignity. As Watson puts it, "Of course Rosy knew of Linus' success but saw no obvious reason to ape his mannerisms…only a genius of his stature could play like a ten-year-old boy and still get the right answer" (Watson 69).