El origen de la vida

Review

Endeavour

Vol.30 No.1 March 2006

The origins of research into the origins of life
Iris Fry
The Cohn Institute for the History and Philosophy of Science and Ideas, Tel Aviv University, Tel Aviv 69978, Israel

Most scientists at the end of the 19th and the beginning of the 20th century chose to ignore the question of the origin of life on Earth, regarding it as too mysteriousand complex to handle. Yet, in the early 1950s an experimental field devoted to the study of the problem made its first steps. The pioneering theories of several scientists in the first decades of the 20th century played a major role in this transformation, notably those of the Russian biochemist Alexander I. Oparin and the British geneticist and biochemist J.B.S. Haldane. The ideas of the lesser-knownAmerican psycho-physiologist Leonard Troland also made a significant contribution to subsequent developments in origin-of-life research. Therefore, it is well worth taking a look at the professional, philosophical and ideological commitments that shaped the approaches of the three scientists to origin-of-life research. Introduction In the fall of 1951, Stanley Miller, a young doctoral student atthe University of Chicago, was fascinated and inspired by a lecture delivered by the Nobel Laureate physicist and chemist, Harold Urey. In his lecture, Urey discussed physical and chemical conditions that might have existed on the primordial Earth, and their potential relevance to the emergence of life. Miller convinced Urey to let him try his hand at experimentally simulating these conditions. InMiller’s simulated primordial atmosphere and ocean, contained in a glass apparatus that he designed with Urey, the synthesis of organic molecules, mainly amino acids – the building blocks of proteins, was experimentally demonstrated for the first time in the spring of 1953. The Miller–Urey experiment and many others that followed in the 1950s and 1960s led to the creation of an experimentalscientific field devoted to the elucidation of the origin of life on Earth. Both the empirical setup of these experiments and the philosophical assumptions underlying them can be traced back to several theoretical developments in the early 20th century. In the 1920s and the 1930s, the Russian biochemist Alexander I. Oparin and the British biochemist and geneticist J.B.S. Haldane described possible scenariosfor the emergence of life on Earth, the common elements of which came later to be known as the Oparin– Haldane hypothesis [1]. However, this hypothesis and the theory formulated by the American psycho-physiologist
Corresponding author: Fry, I. (iris.fry@gmail.com).

Leonard Troland in the 1910s had to overcome an impasse in scientific attitudes to the origin of life before they could be acceptedby the scientific community (Figure 1). Two key developments in the late 19th century played a major part in creating this impasse [2]. Experiments performed in the 1860s by the French chemist Louis Pasteur convinced most scientists that organisms, including microorganisms, originated only from their parents and were not, as believed for ages, repeatedly and spontaneously generated from inanimatematter. Simultaneously, Charles Darwin’s Origin of Species, published in 1859, focused attention on the primordial earth. Although it did not explicitly discuss the emergence of life, the concept of Darwinian evolution led to the question that challenged Pastuer’s logic: how did primitive life forms originate in the first place? By the beginning of the 20th century several other factors hadexacerbated this intellectual quandary. New cytological studies revealed the crucial function of the nucleus, which contrasted sharply with established views about the homogeneity of the protoplasm and following the rise of biochemistry, enzymes were being discovered and isolated. The realization that even the simplest of cells was enormously complex convinced many scientists that an ‘impassable...