The Black Box of Biology by Michel Morange

Author:Michel Morange
Language: eng
Format: epub, pdf
Publisher: Harvard University Press

23

Molecular Biology and Evolution

DURING THE YEARS when the molecular vision of life was emerging, it might have seemed to the outside observer that the relationship between molecular biology and evolutionary biology was plain sailing. Both the evolutionary biologists who adopted the Modern Synthesis and the new band of molecular biologists were convinced that all organisms shared common mechanisms that could explain their properties and their evolution. Darwinism was central to the thinking of Max Delbrück, one of the leaders of the phage group which was so active in the development of molecular biology, while Theodosius Dobzhansky, one of the founders of the Modern Synthesis, paid considerable attention to the early results of molecular biology, highlighting Oswald Avery’s discovery even before it was published.

Perhaps surprisingly, the fundamental evolutionary process of variation and selection played a huge part in molecular biologists’ day-to-day experiments on bacteria and bacteriophages; indeed, one of the earliest and most significant contributions of Delbrück and Salvador Luria was to show that the raw material of evolution by natural selection—mutations—arose spontaneously in bacteria, irrespective of the environmental conditions.1 The chief strategy employed by the bacterial and phage geneticists was to explore a particular biological mechanism by creating or isolating mutants that affected the process being studied. This approach was also to prove extremely influential later in the century as researchers turned their attention to more complex, multicellular model systems. The pioneer molecular biologists had no doubt that they would be able to obtain the mutants they needed, whatever the genetic properties they were seeking. Implicitly, they fully acknowledged the creative power of the process of variation and selection, a central aspect of the Modern Synthesis.

In reality, relations between molecular biologists and evolutionary biologists were not quite so amicable. There were repeated disputes, sometimes prompted by professional jealousies as well as conceptual differences. The first signs of disagreement appeared at the beginning of the 1960s, when Ernst Mayr and George Simpson openly opposed the growing power of molecular biologists in universities; this was accompanied by an emphatic distinction between two different forms of biology, and between two different types of questions raised by biologists, which was first put forward by Ernst Mayr.2 Functional biologists, including molecular biologists, asked “how” questions, Mayr argued, whereas evolutionary biologists asked “why” questions. By arguing that evolutionary biology and molecular biology were complementary, Mayr was seeking to defend evolutionary biology against the growing influence of its new rival.

Rather than outlining the transformations of evolutionary biology over the last fifty years, this chapter describes the gradual dovetailing of molecular biology and evolutionary biology, and the difficulties that scientists encountered along the way.

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