The heterotrophic origin of life proposed by A. I. Oparin in the 1920s was part of a Darwinian framework that assumed that living organisms were the historical outcome of a gradual transformation of lifeless matter. Eighty years ago, he presented a much more detailed scheme of the processes that may have led to life. As argued here, the development of the heterotrophic theory has been shaped by an entangled scenario in which a number of technical and scientific developments concur, as well as non-scientific issues including the Stalinist period and the tensions of the Cold War atmosphere. What has been largely ignored until now is the key role played by Haeckel's ideas in shaping Oparin's theory. The heterotrophic theory has been erroneously described as a metabolism-first hypothesis in which genetic material was not included due to ideological pressures of the Soviet government. As shown here, both characterizations are mistaken. The development of Oparin's views and the ensuing debates cannot be understood without considering the confrontation between Mendelism and Darwinism during the first three decades of the past century, combined with the doubts surrounding the existence of genes.
Keywords: Heterotrophic theory; Mendelism; Oparin; Origin of life.