RESUMEN
Georgy Gause (1910-1986) is best known for his contribution to ecology and evolutionary theory. His book "The Struggle for Existence" (1934) inspired generations of ecologists. Yet his scientific interests were diverse, embracing many aspects of the life sciences and medicine. The most notable shift in his research took place in the early 1940s when he began to study antibiotics and discovered Gramicidin S. Superficially, this shift looked like an attempt to switch from purely theoretical to applied research during the years of World War II, but Gause's decision may also have been seriously affected by the "Great Purge" and the growth of Lysenkoism. Personal factors played a significant role in his career too. In this article, we propose four factors which drove Gause to switch his focus from ecology to antibiotics: the inner logic of his scientific research, Stalin's science policy and the growth of Lysenkoism, the sociopolitical influence of World War II, and personal relationships. We will also show how all these factors are interdependent to some extent.