Nevertheless, toward the end of 1951, an unusual paper by biochemist Edward Ronwin, then at the University of California at Berkeley, intrigued Pauling sufficiently to prod him into action. The paper, entitled “A Phospho-tri-anhydride Formula for the Nucleic Acids,” appeared in November 1951. In it, Ronwin proposed a new “design” for DNA, in which each phosphorus atom connected to five oxygen atoms, while Pauling—the consummate structural chemist—was absolutely convinced that it had to link only to four. Annoyed, Pauling fired a quick communication to the editor of the Journal of the American Chemical Society (together with chemist Verner Schomaker) in which they first noted that “in formulating a hypothetical structure for a substance, one must take care that the structural elements of which use is made are reasonable ones.” Their conclusion was even more dismissive: “The ligation of five oxygen atoms about each phosphorus atom is such an unlikely structural feature,” they said, that the proposed formula for DNA “deserves no serious consideration.” Ronwin retorted by pointing out that other substances in which phosphorus was bonded to five oxygen atoms did exist. Pauling and Schomaker had to withdraw their disparaging statement, but they still insisted correctly on the fact that structures of this type were extremely sensitive to moisture, which made them unlikely candidates for DNA. This exchange would have been insignificant except that it did get Pauling thinking about how DNA might be constructed. To make progress, however, he needed high-quality X-ray diffraction photographs of DNA, since the ones available in print were old photos taken by William Astbury and Florence Bell in 1938 and 1939. Unfortunately, good X-ray photos were not easy to come by. Caltech did produce new photographs in the early 1950s, but, surprisingly, those turned out to be of inferior quality to those of Astbury and Bell. While weighing his options, Pauling heard that Maurice Wilkins of King’s College, London, had generated what were described as “good fibre pictures of nucleic acid.” Deciding that he had nothing to lose, Pauling wrote to Wilkins to inquire whether the latter was prepared to share those photos. Unbeknown to Pauling, however, the activity around DNA in England was rapidly approaching frenzy.

Three separate events, all happening in 1951, proved to be fateful for the “race” to uncover the structure of DNA. In that year, Francis Crick, at age thirty-five, was working at Cambridge toward a PhD degree in biology after having been bored with physics. (He later described his work on the viscosity of water as “the dullest problem imaginable.”) His mathematical background would be crucial for the discoveries to come. In the same year, James Watson, then twenty-three, arrived at Cambridge to learn about X-ray diffraction from Max Perutz. Watson had completed his PhD at the University of Indiana on the effects of X-rays on viruses and later had some training in nucleic acid chemistry at the University of Copenhagen. Also in 1951, Rosalind Franklin, then thirty-one, came to King’s College, after having completed three years of research in Paris, where she became proficient in X-ray diffraction techniques.

Franklin, who came from an erudite banking family, had earned her PhD from Cambridge in 1945. When she arrived at King’s College, physicist Maurice Wilkins was hoping that by virtue of her being an accomplished crystallographer, she would help him in his studies of molecular structure. That Wilkins would expect that of Franklin was not at all surprising, since at the time, according to Watson’s account, “molecular work on DNA in England was, for all practical purposes, the personal property of Maurice Wilkins.” This was not at all, however, what Franklin had in mind when she signed up to come to King’s, and she had good reasons for her different presumption. Sir John Randall, director of the college’s Biophysics Research Unit, had written her a letter in which he described her job as follows: “This means that as far as the experimental X-ray effort is concerned there will be at the moment only yourself and Gosling [Raymond Gosling, who was a graduate student at the time], together with the temporary assistance of a graduate from Syracuse, Mrs. Heller.” Franklin was therefore under the logical impression that she was going to be her own boss as far as the DNA work was concerned—an attitude that clearly conflicted with Wilkins’s assumptions. Consequently, Franklin and Wilkins were bound to clash, and they did. Later, they ended up working separately, even though they shared the same laboratory quarters.

By contrast, Watson and Crick, who were sharing an office at Cambridge, hit it off right away. Watson described Crick as “no doubt the brightest person I have ever worked with and the nearest approach to Pauling I have ever seen.” The two men brought together rather different but complementary expertise, traits, and temperaments. As Crick noted in an interview, “The interest was that his [Watson’s] background was in phage work which I had only read about and did not know first hand and my background was in crystallography which he had only read about and did not know first hand.” It is amusing to read how they described each other’s personality. Referring to Crick’s assuredness, puckish wit, and habit to speak his mind, Watson wrote about him, “I have never seen Francis Crick in a modest mood.” He also added that Crick “talked louder and faster than anyone else.” On the other hand, Crick wrote about Watson, “Jim was distinctly more outspoken than I was.” Despite the different backgrounds, something clicked immediately between the two. Crick suspected that this was “because a certain youthful arrogance, a ruthlessness, and an impatience with sloppy thinking” came naturally to both of them. Their thought processes were also fairly similar. In Crick’s words, “He was the first person I had met who thought the same way about biology as I did . . . I decided that genetics was the really essential part, what the genes were and what they did.”

There was something else that made the Watson-Crick collaboration truly powerful. Because neither of them was professionally senior to the other, they could afford to be brutally honest in criticizing each other’s ideas. This type of intellectual honesty is sometimes missing in relationships burdened by formal politeness, bowing to one’s superiority, or by one or the other pulling rank. This is how Crick himself described his interaction with Watson: “If either of us suggested a new idea, the other, while taking it seriously, would attempt to demolish it in a candid but nonhostile manner.” According to Crick, Watson “was determined to discover what genes were and hoped that solving the structure of DNA might help.” This turned out to be absolutely true.