The Invention of the Genetic Code
On the last day of February in 1953, according to James Watson, Francis Crick announced to the patrons of the Eagle pub in Cambridge, "We have discovered the secret of life." History supports the boast. If life ever had a secret, the double helix of DNA was surely it. And yet Watson and Crick had not laid bare all the secrets of molecular biology. The campaign to understand the code embodied in the double helix was just beginning, and the years ahead would be notable for frustration, false starts and brilliant ideas that turned out to be utterly wrong. It took another full decade to solve the code.
Some weeks ago I found myself browsing in the literature of that curious decade. I had come upon one paper by chance, while looking for something else, and was so intrigued that I tracked down some of the earlier works it cited. A few days later I came back to peel away another layer of references. Then I shifted forward in time to read later summations and histories. (This kind of truffle-hunting in the library stacks is especially engaging when you're supposed to be doing something else.)
What fascinated me about the code-breaking effort was how quickly a biochemical puzzle—the relation between DNA structure and protein structure—was reduced to an abstract problem in symbol manipulation. Within a few months, all the messy molecular complexities were swept away, and the goal was understood to be a mathematical mapping between messages in two different alphabets. The methods for devising codes came from combinatorics; the proposed solutions were judged largely by the criteria of information theory. Efficient storage and transmission of information seemed all-important. The coding theorists were trying to learn the language of the genes, but they might as well have been designing a communications protocol for a computer network.
I was fascinated for another reason as well: Some of the proposed codes were truly ingenious. Indeed, it was hard not to feel a twinge of regret on coming to the end of the story and learning the right answer. Compared with the elegant inventions of the theorists, nature's code seemed a bit of a kludge.