This article studies how our understanding of population-level disease transmission has evolved over time. The main question is: what happens to ‘facts’ in the course of their life history? The concept of life history captures the process that shapes the facts of disease transmission, mobilizes them via mathematical and graphical representations, and allows them to evolve and change over time. Hence, this concept provides continuity from knowledge production to utilization. Life history is developed through phases in the ‘lives’ of ‘facts’: birth and youth, adulthood and reproductive years, and old age. The life-history approach consists of a set of ‘facts’ binding together knowledge of a disease, its routes of transmission, and the susceptibility of the exposed population; it thus provides an adequate framework to explore the complex nature of population-level disease transmission. The analytical focus of this article is concerned with how these ‘facts’ are disseminated via model-based or mathematical representations. Just as life histories are stories full of interactions, surprises and struggles, this article highlights the underlying contingencies in the dissemination and accumulation of factual knowledge.