Published today in Proceedings of the Royal Society B , anthropologists at UCL, in collaboration with researchers from Lanzhou University, China, explored lifelong religious celibacy in Tibetan monks in Western China.
The researchers found that parents used to make one son a Buddhist monk to help the economic and reproductive prospects of their non-celibate sons, ultimately helping their family thrive - and not simply for religious tradition.
Overall, the researchers found that religious celibacy can be essential for adaptive evolution, and conclude that celibacy can only evolve if it benefits the monk’s brothers, and the decision is taken by parents, and not the boys themselves.
To establish their findings, researchers undertook interviews with 530 households across 21 villages in the eastern part of the Tibetan Plateau, in Gansu Province, China. Respondents were asked about their family history, numbers of siblings, children, and grandchildren and whether any of them had ever been a Buddhist monk.
Lead-author Professor Ruth Mace (UCL Anthropology) said: "Many major world religions often require some of their practitioners to commit to lifelong celibacy, for example monks in Buddhism and priests in the Catholic Church. This behaviour is puzzling from an evolutionary perspective, as celibates - and their parents who often influence this decision - choose not to have children.
"Surprisingly, we found that men who sent one son to the monastery as a young boy have more grandchildren. This is because Buddhist monks cannot inherit property, so their non-celibate brothers are wealthier and can support larger families.
"Here we have shown that, when adopting a new custom, people consider the potential economic outcomes. Parents send a son to the monastery not simply because they follow religious tradition, but because this decision helps their family thrive."
The authors also built a mathematical model to understand the behaviour, allowing them to understand what conditions help a behaviour such as this become more common.
Co-author Dr Alberto Micheletti (UCL Anthropology) said: " The spread of new ideas and powerful institutions can lead people to act against their interests. But this is not always the case and evolutionary models allow us to understand what conditions help a behaviour become more common.
"In our model, celibacy can only evolve if it benefits the monk’s brothers and the decision is taken by parents, not the boys themselves. This is exactly what we found in our Tibetan study population. "
Evie Calder(0) 7858 152143
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