Self-denial by shamans promotes perceptions of religious credibility Manvir Singh* and Joseph Henrich Department of Human Evolutionary Biology, Harvard University, Cambridge, MA 02138 *Corresponding author:
[email protected] 3 July 2019 Abstract Religious leaders refrain from sex and food across human societies. Researchers argue that this self-denial promotes perceptions of credibility, invoking such associations in explanations of shamanism and prosocial religion, but few, if any, quantitative data exist testing these claims. Here we show that shamans in a small-scale society observe costly prohibitions and that observers infer three dimensions of credibility – cooperativeness, religious belief, and supernatural power – from shamans’ self-denial. We investigated costly prohibitions on shamanic healers, known as sikerei, among the rainforest horticulturalist Mentawai people of Siberut Island. We found that shamans must observe permanent taboos on various animals, as well as prohibitions on sex and food during initiation and ceremonial healing. Using vignettes, we evaluated Mentawai participants’ inferences about self-denial, testing three mechanisms of religious credibility: cooperative costly signaling, credibility-enhancing displays, and supernatural otherness. We found support for all three mechanisms: Mentawai participants infer self-denying shamans to be (1) cooperative, (2) sincere believers in the religious rules, and (3) dissimilar from normal humans and with greater supernatural powers. These data provide novel, quantitative evidence that self-denial develops to promote perceptions of practitioners’ religious credibility. Introduction Religious self-denial, whether enforced or apparently voluntary, is ubiquitous. The renunciation of sex, valuable food, or social contact has been practiced by Catholic priests, Buddhist and Jain clergy, Taoist monks and nuns, Christian monastic sects, and many other practitioners who devote themselves to communing with the divine (Bell & Sobo, 2001; Gross, 1992).