Metabolism, Heredity and Catalysis

Reading Iris Fry's The Emergence of Life on Earth Chapter 6

Not much progress on understanding the origin of life was possible until some understanding of the mechanisms of life was achieved. Some physics and a lot of chemistry were required before it could be discovered how living things went about the business of growing, developing, and reproducing.

Underlying all living activity is metabolism - the systematic production of chemical changes that consumed energy, changed its form, and used it to produce motion or new components of living things. It gradually became understood that highly specific catalysts (enzymes) were the master chemists at work in living cells. Meanwhile, Mendel's laws of genetics had made possible an "atomic theory" of inheritance. Heredity was apparently embodied in discrete form, rather than as some mysterious and continuously variable fluid.

Leonard Trolland, writing in 1914, realized that a gene too could be considered a sort of catalyst - a catalyst that catalyzed not only its own production but also production of other things. He was thus able to suggest a plausible candidate for original life - a molecule that could catalyze its own production and also the production of some other substance or substances of use to it. At that point, of course, little was understood of the structure of biological catalysts (enzymes) and nothing was understood of the structure of genes.

These two aspects of life, metabolism and heredity, became the respective foci of the the origin of life pioneers Alexander Oparin and J. B. S. Haldane. Oparin, working in the Soviet Union in the twenties and thirties was in an ideology broadly sympathetic to his kind of ideas about the origin of life - they fitted well with some ideas of dialectical materialism and Friedrich Engels. Fry notes that:

...many historians of science and scientists

are of the opinion that it is not mere coincidence that Haldane, Oparin, and several other pioneers in the science of origins were Marxists. Whatever.

Perhaps the biggest contribution of this age was the Oparin-Haldane Hypothesis: the notion that conditions on the primeval Earth were much different from the present, and especially that it then had reducing atmosphere which would favor the formation of organic molecules which would be destroyed by the modern oxygen atmosphere. As earlier noted by Darwin, organic molecules which today would be quickly scarfed up by life would not suffer such a fate on a prebiotic Earth.