Figure and Ground -- Whose Idea Was This?

The root of modern molecular genetics grew from the 1944 findings by Avery, MacLeod, and McCarty and the 1952 experiment of Hershey and Chase (sometimes called the "Waring Blender experiment" because it involved using a blender to purée bacteria cultures) that demonstrated that DNA is genetic material. Shortly after that, Watson and Crick determined the structure of DNA, and over the course of the next decade it was demonstrated that: DNA contains descriptions of protein sequences; it is used to create RNA as an intermediary; gene expression is regulated by proteins that interact with regulatory sites on the DNA; and other varieties of RNA, along with ribosomes, are what catalyze the final translation to proteins. All these parts of the basic, high-school-biology picture of DNA, along with the interpretation of the protein-encoding code were in place by the middle of the 1960's. Together it all makes a consistent and appealing picture of how development works, including how genetic information is transferred from one generation to another.

In their landmark 1961 paper describing the apparatus by which gene expression is regulated, François Jacob and Jacques Monod suggested that the combination of protein encodings and regulatory apparatus would make an organism's DNA comparable to a "program" which would produce a cell or an organism, when executed. Evelyn Fox Keller writes that this was the first use of the idea in the scientific literature.¹¹ Though talk of the "code" was by then common, this was the first serious theoretical hypothesis about it. Keller points out that because the regulatory agents (proteins) are also genetic products, it was easy to conclude that the whole is a self-contained process, with the regulatory products interspersed with the regulators themselves. Though the protein code was not known at the time, its elucidation was imminent, and it was easy to make the leap into the realm of the abstract.

Most of the early molecular geneticists avoided much theorizing beyond the biochemical domain in which they worked. The great advances of the 1950's and 1960's were almost all framed as problems in biochemistry: not "How does inheritance work?", but "What are the steps in protein synthesis?" Not "What is the language of life?", but "How does DNA code for proteins?" The landmark achievements were accomplished with years of painstaking experiment. What few purely theoretical efforts had been made had largely led to dead ends, like George Gamow's various code attempts, and Francis Crick's development of the comma-free code, an elegant, but mistaken, hypothesis.¹² Indeed, several of the vanguard rebuffed attempts at assistance from mathematicians and information theorists.¹³ But what the first generation found easy to resist, the next generation found irresistible, and though the first generation resisted, their casual use of language encouraged those who followed. In several papers, published and unpublished, and in correspondence, the leading lights of molecular biology spoke about "codes," "cybernetics," and "information." For example, in the follow-up to their famous paper elucidating the structure of DNA, Watson and Crick said:

The phosphate-sugar backbone of our model is completely regular, but any sequence of the pairs of bases can fit into the structure. It follows that in a long molecule many different permutations are possible, and it therefore seems likely that the precise sequence of the bases is the code which carries the genetical information.¹⁴

Abstracted as a language or a code, genetic "information" can exist in its own abstract domain, available for theoretical analysis on its own terms, and dissociated from the dull considerations of mere "context"-- energy budgets, coenzymes, and the like. But in fact, this context in which DNA exists--the nucleus of a cell--is itself filled with implicit information and information-bearers. Considering genetic information apart from its context, and expecting to be able to do anything with it, is an error roughly comparable to imagining that a dictionary would be all one would need for a useful translation of Huckleberry Finn into Bwaidoka.

To translate that book, or this one, into a culture unlike ours, you have to add what would be understood here. In a place where elevators are scarce you might have to add information about elevators. To readers who won't know about cells, you need to add something about them. To translate the DNA into a human-readable form, you have to add information about the context in which the DNA is to be read. You have to make explicit information that is implicit in the construction of the cell from which the DNA came.