Reframing oxytocin as a behavioral flexibility hormone

Oxytocin is a neuropeptide that has historically been recognised for its role in childbirth, lactation, and sexual reproduction. Subsequently, research expanded its influence to include social bonding and behaviors, emphasising its role in facilitating interpersonal relationships. More recent studies, however, have revealed its broader influence, extending to non-social behaviors and cognitive processes, underscoring its ability to modulate a diverse array of behavioral and mental functions. This evolving understanding calls for a critical re-evaluation of oxytocin's classification as a "social" hormone. The Allostatic Theory of Oxytocin, which integrates both psychological and physiological dimensions, provides an alternative framework that accounts for how oxytocin modulates both social and non-social behaviors. At the core of this framework is behavioral flexibility, which is essential for adapting to dynamic environments. In this review, we explore the role of oxytocin in facilitating behavioral and cognitive flexibility using mechanistic and evolutionary perspectives. Additionally, we describe the neurobiological mechanisms that support oxytocin's influence on behavioral flexibility. Collectively, our findings underscore the benefits of reframing oxytocin's function in behavior within a broader framework that encompasses both social and non-social aspects. This more expansive perspective not only deepens our understanding of oxytocin's multifaceted roles, but also opens avenues for novel research approaches.