RESUMO
We examine the emergence of the field of life-history strategies during the 1950s. (We consider a 'field' an area of scientific activity consisting of a theoretical core, a subject of research, a vocabulary and research tools). During the late 1940s and early 1950s, population ecology faced many problems, concerning its conceptual framework, its mathematical models, experimental deficiencies, etc. Research on life-history characteristics remained descriptive, lacking explanations about the causes and significance of phenomena. This was due to the deficiencies of the theoretical framework of population ecology up to the 1950s. The catalyzing factor for the emergence of the new field was the interdisciplinary impacts, and especially the impact of neodarwinism. The elaboration of a new theoretical core, invoking also methodological shifts, was the triggering factor, conditioning the emergence of the new field.