This paper challenges the prevalent characterization of domesticated horses as prey species that inherently view humans as predators. Drawing on evolutionary, ethological, and cognitive evidence, we propose the "mutualistic coevolution hypothesis", which posits that horses and humans have evolved a partnership marked by cooperation rather than fear. We critically assess the "prey hypothesis", emphasizing a predator-prey model, which dominates equine training and the literature, and we argue that it inadequately explains horses' morphology, behaviors, and cognitive capacities. Comparative studies on horses' socio-cognitive skills suggest that domestication has fostered emotional, behavioral, and cognitive adaptations supporting a human-horse bond. This review examines evidence from archaeological findings and experimental research on horses' responsiveness to human gestures, emotions, and social cues, underscoring their complex cognition and capacity for collaboration. Furthermore, morphological and behavioral analyses reveal inconsistencies in using orbital orientation or predation-related traits as evidence for categorizing horses as prey species. By emphasizing the coevolutionary dynamics underlying human-horse interactions, we advocate for replacing traditional training models centered on fear and submission with approaches that leverage horses' mutualistic and social nature. This perspective offers insights for enhancing horse welfare and improving human-equine relationships.