(ORDO NEWS) — Why would someone join an organization that deprives him of the possibility of family life and requires him to be celibate? After all, reproduction is at the heart of the evolution that has shaped us.
However, many religious institutions around the world require just that. This practice has led anthropologists to wonder how celibacy could have come about in the first place.
Some have suggested that practices that cost individuals dearly, such as never having children, can still emerge when people blindly follow norms that benefit the group cooperation is another cornerstone of human evolution.
Others argue that people end up creating religious (or other) institutions because it serves their own selfish or family interests, and reject those who are not involved.
Now our new study, published in the Royal Society Proceedings B and conducted in Western China, addresses this fundamental question by examining lifetime religious celibacy in Tibetan Buddhist monasteries.
Until recently, it was customary for some Tibetan families to send one of their young sons to a local monastery to become a lifelong celibate monk.
Historically, up to one in seven boys became monks. Families usually cited religious motives for having a monk in the family. But were there also economic and reproductive considerations?
Together with our colleagues from Lanzhou University in China, we interviewed 530 families in 21 villages in the eastern Tibetan Plateau, in Gansu province. We reconstructed the family genealogy by gathering information about each person’s family history and whether any of their family members were monks.
These villages are inhabited by the patriarchal Tibetans of Amdo, who raise herds of yaks and goats and cultivate small plots of land. Wealth in these communities is usually passed down through the male line.
We found that men whose brother was a monk were richer and owned more yaks. However, the sisters of the monks had almost no advantages. This is probably due to the fact that brothers compete for parental resources, land and livestock.
Since monks cannot own property by sending one of their sons to a monastery, the parents put an end to this fraternal conflict. The first-born sons usually inherit the parent household, while the monks are usually the second or later sons.
Surprisingly, we also found that men with a monk brother had more children than men with non-celibate brothers; and their wives, as a rule, gave birth to children at an earlier age.
Grandparents with a monk son also had more grandchildren, as their non-celibate sons faced less or no competition from their brothers. Thus, the practice of sending a son to a monastery without being costly to the parents is in their reproductive interests.
Mathematical model of celibacy
This hints that celibacy may evolve through natural selection. To find out the details of how this happens, we built a mathematical model for the evolution of celibacy, in which we examined the effects of becoming a monk on the evolutionary fitness of a man, his brothers, and other members of the village.
We modeled both the case when the decision to send the boy to the monastery is made by the parents, as was the case in our field study, and the case when the boy makes the decision himself.
If the monks remain unmarried, this means that there are fewer men in the village who want to marry women. But while all the men in the village stand to gain if one of them becomes a monk, the monk’s decision is not conducive to his own genetic health. Therefore, celibacy should not evolve.
However, the situation changes if having a monk brother makes men richer and therefore more competitive in the marriage market. Now religious celibacy can evolve through natural selection, because although the monk has no children, he helps his brothers have more children.
But, importantly, if the choice to become a monk depends on the boy himself, then most likely he will remain rare – from the point of view of the individual, this is not very profitable.
In the model, we show that celibacy only becomes much more common if parents decide that it should happen. Parents benefit from all their children, so they will send one of them to a monastery if it benefits the others.
The fact that boys were sent to the monastery at a young age, with great triumph, and were threatened with disgrace if they subsequently abandoned their role, speaks of a cultural practice shaped by parental interests.
This model could potentially also shed light on the evolution of other kinds of parental favoritism in other cultural contexts – even infanticide.
A similar pattern may explain why female celibacy (nuns) is rare in patriarchal societies such as Tibet, but may be more common in societies where women are in more competition with each other for example, where they have more inheritance rights (as in some parts of Europe).
We are currently developing new research to understand why the frequency of monks and nuns varies across religions and parts of the world.
It is often assumed that the spread of new ideas – even irrational ones – can lead to the creation of new institutions as people conform to the new standard. But it may turn out that institutions can also be shaped by people’s reproductive and economic decisions.
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