A Twist Of Fate

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But while biologists freely used the word gene to mean the "smallest unit of genetic information," they didn't have a clue what a gene actually is. And with far more self-assurance than a newly minted 22-year-old Ph.D. had any right to possess, Watson decided he would figure it out. His first stop was Copenhagen for a postdoctoral fellowship with the biochemist Herman Kalckar, who was studying DNA's chemical properties. The fellowship ended in a hurry. "Herman," writes Watson in The Double Helix, "did not stimulate me in the slightest." Even worse, he decided Kalckar's research would not immediately lead to an understanding of the gene.

During a conference in Naples, Italy, in the spring of 1951, Watson happened to sit in on a lecture by Maurice Wilkins of King's College, London, who was using X-ray diffraction to try to understand the physical structure of the DNA molecule. When you shine X rays on any sort of crystal--and some biological molecules, including DNA, form crystals--the invisible rays bounce off atoms in the sample to create complex patterns on a piece of photographic film. In principle, you can look at the patterns and get important clues about the structure of the molecules that make up the crystal. In practice, the patterns in DNA are hellishly hard to disentangle.

But Watson was elated. Wilkins' image suggested that DNA had a regular crystalline structure. By figuring out what that structure is, moreover, one might be in a better position to understand how genes work. Here was someone who appreciated what Watson already believed but which many scientists didn't yet accept: that the genetic code was somehow tied up in the physical structure of DNA. He realized he needed to understand X-ray diffraction and wanted to join Wilkins in London but never got an opportunity to ask him. So Watson wangled the next best position--a fellowship at the Cavendish Laboratory in Cambridge, where the director, Sir William Lawrence Bragg, had (with his father Sir William) developed X-ray crystallography in 1912-14.

It was there, in the fall of 1951, that Watson initially met Crick. (He actually met Crick's wife Odile first. Her only comment afterward: "He had no hair!"--a reference to Watson's crew cut.) Like Wilkins, Crick was a physicist who switched into biology; like Wilkins and Watson, Crick had been impressed with Schrodinger's What Is Life? He wasn't actually studying DNA, though; at age 35, thanks in part to a hiatus for military work in World War II, he was still pursuing his Ph.D. on the X-ray diffraction of hemoglobin, the iron-carrying protein in blood. Watson, meanwhile, had gone to Cambridge to use X-ray diffraction to understand the structure of another protein, myoglobin.

But whatever their formal duties, both men were determined to figure out what genes were, and both were convinced that understanding the structure of DNA would help them do that. "Now, with me around the lab always wanting to talk about genes," writes Watson in The Double Helix, "Francis no longer kept his thoughts about DNA in a back recess of his brain ... No one should mind if, by spending only a few hours a week thinking about DNA, he helped me solve a smashingly important problem."