THE CENTURY OF THE GENE

The author of Refiguring Life (1995) assesses a hundred years of progress in genetics, perhaps the most exciting area in modern science, focusing on the conceptual problems inherent in the little understood nature of the gene itself.

As Keller (History and Philosophy of Science/MIT) points out, the word “gene” came into being in 1906 as a shorthand term for the elementary unit of heredity implied by Mendel’s experiments. It took nearly half a century for biologists to understand what it meant. First came the recognition that the expression of a gene was in the form of specific enzymes, then the realization that one particular molecule, DNA, guided the formation of enzymes. Genetics found its “central dogma” when Crick and Watson described the structure of DNA and explained how it passes its information to messenger RNA to instruct ribosomes which proteins are to be made. Complications in this model began to arise shortly after it was announced, for example in the discovery of “junk DNA,” which (while very common) appears to fulfill no genetic purpose. Other genes have been found to code for more than one protein, a clear contradiction of the earlier concept. The focus for the last two decades has been on the idea of a “genetic program,” the interaction of genes to produce an entire living organism. This process must be extremely subtle; humans and chimpanzees differ in their genetic makeup by only 1.5 percent, yet the external differences are obvious to a child. In the end, Keller argues, we may have reached the point where the concept of the “gene” has become a hindrance to understanding what is really going on in a given organism or species. A new vocabulary is beginning to emerge that will make it possible for both scientists and laypeople more clearly to describe the ongoing progress in our understanding of how life works on the most fundamental level.

A detailed, often highly technical examination of a key scientific idea of the past century.