One Health: An epistemological genealogy.

The concept of One Health is commonly framed as an integrative model linking human, animal, and environmental health. While this articulation has been essential for policy development and institutional alignment, it remains descriptive mainly and can obscure the paradigm's epistemological foundations. This article argues that One Health should be understood not merely as a coordination framework, but as the contemporary consolidation of a long-standing interdisciplinary mode of knowing health. Using a genealogical approach, we trace convergent lines of thought across philosophy, ecology, medicine and veterinary science, public health, nursing, and social sciences. Across these traditions, recurring commitments emerge: health as relational and situated; causality as multi-level, non-linear, and distributed across human-animal-environment interactions; and ethical responsibility toward the ecological conditions that sustain life. Recognising this lineage reframes One Health as a way of knowing: one that requires concepts, methods, and responsibilities commensurate with entangled human-animal-environment realities.