The 'inner life' of animals revealed by Frans de Waal: the 'point of no return' for the concept of animal wellbeing

This paper explores Frans de Waal’s pivotal role in reshaping scientific and ethical perspectives on animal emotions and their relevance for contemporary understandings of animal wellbeing. Building on evolutionary continuity, de Waal challenged “anthropodenial” and demonstrated that emotions are evolutionarily conserved, embodied states shared across species that regulate adaptive responses across taxa. Evidence from neurobiology, endocrinology, and behavior supports the view that animals express evolutionary homologous emotional responses and rely on these states for social communication, coordination, and decision-making. Mechanisms such as emotional contagion, sympathetic concern, and empathy – conceptualized through the Perception-Action Model and the “Russian doll” framework – highlight the depth of animals’ affective lives. The paper further examines cognitive bias paradigms as tools for assessing emotional states and emphasizes how environmental conditions shape animals’ expectations and emotional outlook, and how captive environments, by restricting agency and altering perceptual experience, may impair wellbeing. Drawing on philosophical notions of eudaimonia, hedonia, and social connectedness, the paper argues for a shift toward wellbeing-centered approaches that prioritize animals’ inner lives. Recognizing animals’ emotional subjectivity marks a turning point for welfare science, shifting focus from resource-based definitions to wellbeing-centered frameworks grounded in affect, agency, and experiential quality