Watson and Crick Explain How DNA Carries Genetic Information
In 1953, when James Watson pushed around some two-dimensional cut-outs and was startled to find that an adenine-thymine pair had an isomorphic shape to the guanine-cytosine pair, he solved eight mysteries simultaneously. In that instant he knew the structure of DNA: a helix. He knew how many strands: two. It was a double helix. He knew what carried the information: the nucleic acids in the gene, not the protein. He knew what maintained the attraction: hydrogen bonds. He knew the arrangement: The sugar-phosphate backbone was on the outside and the nucleic acids were in the inside. He knew how the strands match: through the base pairs. He knew the arrangement: the two identical chains ran in opposite directions. And he knew how genes replicated: through a zipper-like process.
The discovery that Watson and Crick made is truly impressive, but I am also interested in what we can learn from the process by which they arrived at their discovery. On the surface, the Watson-Crick story fits in with five popular claims about innovation, as presented below. However, the actual story of their collaboration is more nuanced than these popular claims suggest.
It is important to have clear research goals. Watson and Crick had a clear goal, to describe the structure of DNA, and they succeeded.
But only the first two of their eight discoveries had to do with this goal. The others, arguably the most significant, were unexpected byproducts.
Experience can get in the way of discoveries. Watson and Crick were newcomers to the field and yet they scooped all the established researchers, demonstrating the value of fresh eyes.
However, Watson and Crick as a team actually had more comprehensive expertise than the other research groups. The leading geneticists didn't care about biochemistry; they were just studying the characteristics of genes. The organic chemists who were studying DNA weren't interested in genetics. In contrast Crick had a background in physics, x-ray techniques, protein and gene function. Watson brought to the table biology, phages, and bacterial genetics. Crick was the only crystallographer interested in genes. Watson was the only one coming out of the U.S.-based phage group interested in DNA.
Fixation on theories blinds you to the data. Many of the researchers at the time had been gripped by a flawed belief that proteins carried the genetic information, because DNA seemed too simple with only four bases. That was the handicap that the experienced researchers carried, not their expertise. Watson and Crick, being new to the field, weren't fixated by the protein hypothesis and were excited by new data suggesting that DNA played a central role in genetic information.
On the other hand, excessive reliance on data also carries a penalty because the data can be flawed. Rosalind Franklin was handicapped in her research by earlier results that had mixed dry and wet forms of DNA. She pursued the dry form of DNA, whereas she needed to be studying the wet form. She didn't have the over-arching theory of Watson and Crick that DNA must be a helix, which would have helped her make sense of her own data. She ignored an important photograph for 10 months whereas Watson was struck by its significance as soon as he saw it. As modelers, Watson and Crick benefited from a top-down perspective that helped them judge which kinds of data were important.
Also, Watson and Crick were gripped by a flawed theory of their own. They believed that DNA would be a triple helix, a belief that sent them off in some wrong directions but also provided them with concrete ideas they could test. They were in a "speculate and test" mode rather than trying to keep an open mind.
Pressure for results gets in the way of creativity. No granting agency was sponsoring their research. They didn't have to demonstrate progress in order to get funding renewal.
Actually, the two of them felt enormous pressure to unravel the mystery of DNA, particularly when Linus Pauling showed interest. Unlike Pauling or any of the other research groups, Watson and Crick perceived themselves to be in a frantic race for the prize.
Scientists need to safeguard their reputation for accuracy. Scientific reputations are important. You won't be taken seriously as a scientist if you are seen as doing sloppy research or jumping to unfounded conclusions. For example, Oswald Avery had shown in 1944 that bacterial genes were carried by DNA. But the scientific community thought that Avery's work lacked the necessary controls. He wasn't seen as a careful researcher and his findings weren't given as much credence as they deserved.
However, Watson and Crick weren't highly regarded either. Rosalind Franklin was put off by their eagerness to speculate about questions that would eventually be resolved by carefully gathering data. When Watson and Crick enthusiastically unveiled their triple helix model to her in Cambridge she had little difficulty shooting it down.
I think this last issue is the most important. Too many scientists are very careful not to make errors, not to make claims that later have to be retracted. For many, the ideal is to only announce results that can withstand all criticisms, results that can't possibly be wrong. Unfortunately, the safer the claim, the lower the information value. Watson and Crick embody an opposite tendency, to make the strongest claim that they can defend.