Precellular System Models and the Struggle Against Reductionism: Revisiting a Scientific and Philosophical Debate

This article provides a discussion of the scientific, intellectual, and ideological frameworks that influenced Oparin's formulation of the heterotrophic theory of the origin of life. Based on a Darwinian perspective, Oparin rejected the generally accepted idea that the first entities were photosynthetic microbes. He proposed instead that life had emerged through a gradual, stepwise, non-teleological process of prebiotic evolution that started with the abiotic synthesis and accumulation of organic compounds on primitive Earth. Influenced by Haeckel's and Timiriazev's evolutionary ideas and by biochemical oxidation processes proposed by Bakh, Oparin concluded that the first organisms were anaerobic heterotrophs that had evolved from colloidal aggregates such as gels and coacervate-like systems. In sharp contrast to proposals that explained the origin of life with the chance appearance of viruses or living molecules, Oparin's theory connected the emergence of fermentative cells as the first life-forms with the early evolution of Earth. The construction of a stepwise, slow evolution of different stages suggested by Oparin with colloids and coacervate as models of precellular evolution separated the biochemical and chemical origin of life from the idea of spontaneous generation and led to the development of a multi- and interdisciplinary research program.