The Penguin History of the World

In a measure, the baton passed after 1945 from the physical to the biological or ‘life’ sciences. Their current success and promise have, once again, deep roots. The seventeenth-century invention of the microscope had first revealed the organization of tissue into discrete units called cells. In the nineteenth century, investigators already understood that cells could divide and that they developed individually. Cell theory, widely accepted by 1900, suggested that individual cells, being alive themselves, provided a good approach to the study of life, and the application of chemistry to this became one of the main avenues of biological research. Another mainline advance in nineteenth-century biological science was provided by a new discipline, genetics, the study of the inheritance by offspring of characteristics from parents. Darwin had invoked inheritance as the means of propagation of traits favoured by natural selection. The first steps towards understanding the mechanism that made this possible were those of an Austrian monk, Gregor Mendel, in the 1850s and 1860s. From a meticulous series of breeding experiments on pea plants, Mendel concluded that there existed hereditary units controlling the expression of traits passed from parents to offspring. In 1909 a Dane gave them the name ‘genes’.

Gradually the chemistry of cells became better understood and the physical reality of genes was accepted. In 1873 the presence in the cell nucleus of a substance that might embody the most fundamental determinant of all living matter was already established. Experiments then revealed a visible location for genes in chromosomes, and in the 1940s it was shown that genes controlled the chemical structure of protein, the most important constituent of cells. In 1944 the first step was taken towards identifying the specific effective agent in bringing about changes in certain bacteria, and therefore in controlling protein structure. In the 1950s it was at last identified as ‘DNA’, the physical structure of which (the double helix) was established in 1953. The crucial importance of this substance (its full name is deoxyribonucleic acid) is that it is the carrier of the genetic information that determines the synthesis of protein molecules at the basis of life. The chemical mechanisms underlying the diversity of biological phenomena were at last accessible. Physiologically, and perhaps psychologically, this implied a transformation of man’s view of himself unprecedented since the diffusion of Darwinian ideas in the previous century.

The identification and analysis of the structure of DNA was the most conspicuous single step towards a new manipulation of nature, the shaping of life forms. Already in 1947, the word ‘biotechnology’ had been coined. Once again, not only more scientific knowledge but also new definitions of fields of study and new applications followed. ‘Molecular biology’ and ‘genetic engineering’, like ‘biotechnology’, quickly became familiar terms. The genes of some organisms could, it was soon shown, be altered so as to give those organisms new and desirable characteristics; by manipulating their growth processes, yeast and other micro-organisms could be made to produce novel substances, too – enzymes, hormones or other chemicals. This was one of the first applications of the new science; the technology and data accumulated empirically and informally for thousands of years in making bread, beer, wine and cheese was at last to be overtaken. Genetic modification of bacteria could now grow new compounds. By the end of the twentieth century, three-quarters of the soya beans grown in the United States were the product of genetically modified seed, while agricultural producers like Canada, Argentina and Brazil were also raising huge amounts of genetically modified crops.