Gratitude is a complex emotional feeling associated with universally desirable positive effects in personal, social, and physiological domains. Why or how gratitude achieves these functional outcomes is not clear. Toward the goal of identifying its' underlying physiological processes, we recently investigated the neural correlates of gratitude. In our study, participants were exposed to gratitude-inducing stimuli, and rated each according to how much gratitude it provoked. As expected, self-reported gratitude intensity correlated with brain activity in distinct regions of the medial pre-frontal cortex associated with social reward and moral cognition. Here we draw from our data and existing literature to offer a theoretical foundation for the physiological correlates of gratitude. We propose that mu-opioid signaling (1) accompanies the mental experience of gratitude, and (2) may account for the positive effects of gratitude on social relationships, subjective wellbeing, and physiological health.

Spiritual traditions and practices promote a positive and lasting transformation of our experience of self and of the world. Such traditions and practices are ubiquitous in human societies, but it remains unclear why and how they developed. Existing theories on the nature of spirituality range from the suggestion that human minds are inherently predisposed to spirituality, to the idea that spirituality developed adaptively to offer moral guidance and to promote mutually beneficial, cooperative behaviors. Here, we assess this question from the perspective of biological and cultural evolution, and propose that spirituality developed as a cultural adaptation to a characteristic feature of human mental experiencethe duality, or differentiation, of mental subject and mental object. This model traces the development of spirituality to evolutionary events at the core of human exceptionalism, and supports the transformational potential of spirituality in language consistent with scientific knowledge.

In a previous article we proposed that spiritual traditions and practices emerged to counterbalance humans inherent “dualism”, or perceived separation from the world around us, by cultivating experiences of “subject-object nonduality” more commonly referred to as “unification with the divine” or “enlightenment”. This implies that religions (social and political institutions ostensibly based in spiritual practices) similarly aim towards overcoming the separation of self and other. However, many religions include dualistic elements. In particular, many religions incorporate “ethical dualism” in which certain individuals and groups are seen as essentially “good” or “bad”, a feature not seen in nondual traditions. Here, we explore this seeming paradox, highlighting an intriguing correspondence between the degree to which religions include dualistic or nondualistic elements and, respectively, the prevalence of conflict or cooperation as the organizing principle in their associated social context. We find major “dualistic” religions to be generally traceable to pastoral societies largely organized around intergroup conflict, whereas major “nondual religions” are generally traceable to societies in which large-scale cooperation and rule-based behavior was necessary for collective survival. Finally, we apply this pattern to the modern world, speculating that large-scale cooperation and rule-based behavior in modern society may be currently encouraging the renewal of nondual practices in modern social and political institutions that is indicated by the growing popularity of “spiritual but not religious” groups, and that this renewal of nondual practices may in turn set the frame for and reinforce behavior that will be necessary to address the historic challenges of our day like climate change and democratic backsliding.