The Cheshire Cat’s DNA

In 1900, three biologists independently rediscovered Mendel’s laws, according to which the characteristics of organisms are determined by hereditary units, each kind being present once in a gamete, sperm or egg, and hence twice in the fertilized egg. In effect, it was an atomic theory of heredity. The term “genetics” was introduced by William Bateson in 1906, and, for the hereditary units themselves, the word “gene” by Wilhelm Johannsen in 1909. By 1930, Thomas Hunt Morgan and his colleagues, working with the fruit fly Drosophila, had shown that genes are arranged linearly along chromosomes.

In 1953, James Watson and Francis Crick elucidated the structure of DNA, the material of which genes are made, and by so doing suggested a mechanism whereby genes could carry genetic information, and could replicate. There followed in rapid succession the discovery that genes produce their effects by determining the sequence of amino acids in proteins, that they do so by means of a “code” in which a triplet of bases in the DNA specifies an amino acid, and that there is a process whereby one gene can regulate the activity of another. During the last twenty years there has been an explosion in our knowledge of how genes influence the development of animals and plants. Finally, in the year 2000, we await the publication of the complete sequence of the human genome.

It is this history that Evelyn Fox Keller celebrates, and criticizes, in her book. A professor of the history and philosophy of science at MIT, she is at the same time enthusiastic about the light that has been shed on the nature of life and critical of the oversimplifications that she feels have been made. Later in this review I shall argue with some of her conclusions, so I must start by emphasizing that she is well qualified to draw them. She has an admirable grasp of recent research in molecular genetics—certainly wider and more detailed than my own—and has read widely in the history of genetics. I was delighted to meet again in her pages biologists who influenced me when I was starting in research, but whose work I imagined had been forgotten. She has also thought hard about both the history and the current state of the subject. Our disagreements are not of the kind that can be settled by specific experiments or observations; they concern differences about the best strategy to pursue when faced by the complexities of living organisms. I know that the world is complicated, but always seek for simple explanations of the complexity. For Keller, living organisms only work because they are complex; to simplify them is to leave out their essence.

The book can be read by those without previous knowledge of molecular genetics. However, it is not the kind of account I would write if I was aiming at a nonprofessional readership; I would leave out a lot of the complications. Clearly, this is not an option for Keller, because for her …

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