The Information - James Gleick [137]
Plasticule did not catch on, and almost everyone had the wrong idea about heredity anyway. So in 1910 a Danish botanist, Wilhelm Johannsen, self-consciously invented the word gene. He was at pains to correct the common mythology and thought a word might help. The myth was this: that “personal qualities” are transmitted from parent to progeny. This is “the most naïve and oldest conception of heredity,”♦ Johanssen said in a speech to the American Society of Naturalists. It was understandable. If father and daughter are fat, people might be tempted to think that his fatness caused hers, or that he passed it on to her. But that is wrong. As Johannsen declared, “The personal qualities of any individual organism do not at all cause the qualities of its offspring; but the qualities of both ancestor and descendent are in quite the same manner determined by the nature of the ‘sexual substances’—i.e., the gametes—from which they have developed.” What is inherited is more abstract, more in the nature of potentiality.
To banish the fallacious thinking, he proposed a new terminology, beginning with gene: “nothing but a very applicable little word, easily combined with others.”♦ It hardly mattered that neither he nor anyone else knew what a gene actually was; “it may be useful as an expression for the ‘unit-factors,’ ‘elements,’ or ‘allelomorphs.’… As to the nature of the ‘genes’ it is as yet of no value to propose a hypothesis.” Gregor Mendel’s years of research with green and yellow peas showed that such a thing must exist. Colors and other traits vary depending on many factors, such as temperature and soil content, but something is preserved whole; it does not blend or diffuse; it must be quantized.♦ Mendel had discovered the gene, though he did not name it. For him it was more an algebraic convenience than a physical entity.
When Schrödinger contemplated the gene, he faced a problem. How could such a “tiny speck of material” contain the entire complex code-script that determines the elaborate development of the organism? To resolve the difficulty Schrödinger summoned an example not from wave mechanics or theoretical physics but from telegraphy: Morse code. He noted that two signs, dot and dash, could be combined in well-ordered groups to generate all human language. Genes, too, he suggested, must employ a code: “The miniature code should precisely correspond with a highly complicated and specified plan of development and should somehow contain the means to put it into action.”♦
Codes, instructions, signals—all this language, redolent of machinery and engineering, pressed in on biologists like Norman French invading medieval English. In the 1940s the jargon had a precious, artificial feeling, but that soon passed. The new molecular biology began to examine information storage and information transfer. Biologists could count in terms of “bits.” Some of the physicists now turning to biology saw information as exactly the concept needed to discuss and measure biological qualities for which tools had not been available: complexity and order, organization and specificity.♦ Henry Quastler, an early radiologist from Vienna, then at the University of Illinois, was applying information theory to both biology and psychology; he estimated that an amino acid has the information content of a written word and a protein molecule the information content of a paragraph. His colleague Sidney Dancoff suggested to him in 1950 that a chromosomal thread is “a linear coded tape of information”♦:
The entire thread constitutes a “message.” This message can be broken down into sub-units which may be called “paragraphs,” “words,” etc. The smallest message unit is perhaps some flip-flop which can make a yes-no decision.
In 1952 Quastler organized a symposium on information theory in biology, with no purpose but to deploy these new ideas—entropy, noise, messaging, differentiating—in areas