In the fall of 1951, Pauling was not the only one thinking about the structure of DNA.

James Watson realized earlier than most that DNA was the key to learning about genes. In 1951, Watson was on a European postdoctoral fellowship, ostensibly to study microbial metabolism and nucleic acid biochemistry, topics he quickly tired of. In a meeting in Naples, he found a new inspiration when he saw Maurice Wilkins display some of his x-ray photos of DNA. Although Watson did not know much about x-ray crystallography, he realized that Wilkins's work showed that DNA had a regular, repeating structure. He tried to talk his way into Wilkins's lab but knew very little about x-ray crystallography and was turned down; he ended up instead, in the fall of 1951, learning how to diffract x-rays from proteins with John Kendrew at the Cavendish. It was thought wise to give someone with such changeable interests as Watson as much guidance as possible, so he was assigned to share an office with a graduate student of Perutz's who knew crystallography inside and out. His name was Francis Crick. The two men hit it off immediately.

Watson and Crick made quite a pair: Crick, in his mid-thirties, old for a graduate student-his scientific progress delayed by wartime work-but self-confident and outgoing, talkative to a fault, with fashionably long sideburns and a love of three-piece suits; Watson, young, thin, and shy, with his American tennis shoes and crew cut. Erwin Chargaff painted an unkind contemporary picture of them: "One 35 years old, with the looks of a fading racing tout. . . an incessant falsetto, with occasional nuggets gleaming in the turbid stream of prattle. The other, quite undeveloped. . . a grin, more sly than sheepish. . . a gawky young figure." Crick and Watson, he said, looked like "a variety act." But they certainly impressed each other.

When Watson arrived, Crick was ripe for a project that would free him from endless attempts at the mathematical interpretation of hemoglobin diffraction patterns. Within a few days, Watson piqued his interest in a relatively simple and potentially more important target: DNA. They quickly agreed on a method of attack. As Watson put it, they would "imitate Linus Pauling and beat him at his own game."