As evidenced by various posts at this site, I have long been intrigued by the idea that religious rituals are adaptive in that they constitute expensive displays of group loyalty. I recently found a 2004 article by anthropologist Richard Sosis, who has come to this same conclusion. His article, which was published in 2004 by American Scientist (Volume 92), is entitled "The Adaptive Value of Religious Ritual." Sosis holds that "rituals promote group cohesion by requiring members to engage in behavior that is too costly to fake." He thus argues that religious rituals are adaptive in an evolutionary sense. Sosis begins his article by surveying various tedious or grueling religious rituals. His examples include ultraorthodox Jews who wear stiflingly hot clothing in the hot summer, but it also includes Moonies who shave their heads and "Jain monks of India [who] wear contraptions on their heads and feet to avoid killing insects." The list also includes various types of surgical alteration including circumcision and Native American religious rituals that include icy baths, and one ritual that requires the person to lie motionless while being bitten by hordes of ants. The questions raised by these rituals include A) why do people engage in such practices? and B) Is it "rational" to do such things to one's self? Sosis relies upon the research done by "a new generation of anthropologists" in concluding that

The strangeness of religious practices and their inherent costs are actually the critical features that contribute to the success of religion as a universal cultural strategy . . . To understand this unexpected benefit we need to recognize the adaptive problem that ritual behavior solves.