Freud's theorising about anxiety has traditionally been based on its nosographical categories (anxiety neurosis, anxiety hysteria) or on the relationship between anxiety and repression (first and second theories of anxiety). While these types of approach have made it possible to identify some milestones in the development of the concept of anxiety, they have also obscured the relevance that Freud attributed to the phylogenetic argument. This article reviews the historical and conceptual context of Freud's main evolutionary references (Lamarck, Darwin, Haeckel, Weismann), and then analyses their presence and function in Freud's work, especially in his conception of anxiety. The article shows that while some of the evolutionary references became obsolete towards the end of the 19th century, they played such an important role in Freud's work that he never ceased to defend them. With respect to anxiety, though Freud did not make fully public his metapsychological hypothesis about the phylogenetic rationale, this perspective permeates his writing and is fundamental to his development of the concepts of neurotic anxiety/realistic anxiety and automatic anxiety/signal anxiety.
Keywords: Freud; anxiety; phylogenesis.