Religious celibacy brings inclusive fitness benefits

Abstract

The influence of inclusive fitness interests on the evolution of human institutions remains unclear. Religious celibacy constitutes an especially puzzling institution, often deemed maladaptive. Here, we present sociodemographic data from an agropastoralist Buddhist population in western China, where parents sometimes sent a son to the monastery. We find that men with a monk brother father more children, and grandparents with a monk son have more grandchildren, suggesting that the practice is adaptive. We develop a model of celibacy to elucidate the inclusive fitness costs and benefits associated with this behaviour. We show that a minority of sons can be favoured to be celibate if this increases their brothers’ reproductive success, but only if the decision is under parental, rather than individual, control. These conditions apply to monks in our study site. Inclusive fitness considerations appear to play a key role in shaping parental preferences to adopt this cultural practice.

Monks relax sibling competition over parental resources in Tibetan populations

“…We have shown elsewhere that the long-term fitness of parents sending boys to the monastery to become celibate monks is not reduced (Micheletti, Ge, Zhou et al 2022). Here, we test the hypothesis that this is due to decreased competition between sons for parental resources.…”

Religious celibacy brings inclusive fitness benefits

“…Data files for the sociodemographic study are available on the Dryad Digital Repository: [ 67 ] (we reduced the number of covariates to protect the identity of the participants). Electronic supplementary material, information regarding both the sociodemographic study and the inclusive fitness model, and code used to analyse the data and generate the figures are provided in the electronic supplementary material [ 68 ].…”

“…We thank Mark Dyble, Eva Brandl, Mark Pagel, Gonçalo Faria and Andy Gardner and three anonymous reviewers for useful comments. A previous version of this manuscript was deposited as a preprint in OSF Preprints [69] and is available here: https://osf.io/5gur7/.…”

Sex and the clergy: An insider perspective on attitudes towards celibacy

“…Hence, the question of the effects of celibacy on manhood is crucial to understand to ensure the wellbeing of these people. To those who do not commit to abstinence, religious celibacy can be seen as puzzling (Micheletti et al, 2022). Some argue that such a vow is a display of deep commitment to one's beliefs, which in turn aids the perpetuation of the religion because it increases the credibility of the perpetuator (Henrich, 2009).…”