Religious rituals are universal human practices that play a seminal role in community bonding. In two experiments, we tested the role of mu-opioids as the active factor fostering social bonding. We used a mu-opioid blocker (naltrexone) in two double-blind studies of rituals from different religious traditions. We found the same effect across both studies, with naltrexone leading to significantly lower social bonding compared with placebo. These studies suggest that mu-opioids play a significant role in experiences of social bonding within ritual contexts.

Religious rituals are universal human practices, generally practiced in groups. Social scientists have highlighted for over 100 years its role in bonding individuals, but the mechanisms underlying this function have yet to be explored. Here we tested the role of mu-opioids in fostering social bonding in rituals across two double-blind studies. For both studies a mu-opioid blocker (Naltrexone) was taken before the ritual and we assessed strength of social bonding before and after the ritual. Participants were randomly allocated into a placebo or Naltrexone condition. For study 1 (N = 9), we conducted a pilot, yoga-based ritual session in our lab. In study 2 (N = 24), we conducted a naturalistic field study with participants who regularly attended an Afro-Brazilian religious ritual. We found the same effect across both studies, where Naltrexone lead to significantly lower social bonding compared to placebo. These studies show that mu-opioids play a significant role in experiences of social bonding within ritual contexts.

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