by Dimitris Xygalatas | Aeon
On the Day of Ashura, Shia Muslims around the world gather to mourn the Imam, Husayn ibn Ali, and his defeat in the battle of Karbala (in present-day Iraq) in 680 AD. They slash their heads and backs using swords or iron chains with blades until the streets are covered in blood.
Every Good Friday, Catholics in the Philippines re-enact the suffering of Jesus Christ. These devotees are voluntarily crucified by having nails hammered through the palms of their hands and their feet. And every October, thousands of people converge on Phuket in Thailand to celebrate the Vegetarian Festival in veneration of Chinese deities and ancestors; practitioners remove parts of their skin, perform bloodletting, and impale their cheeks and limbs with anything from knives and skewers to antlers and umbrellas—all while burning firecrackers are tossed at them by the crowd.
Widespread participation in such voluntary rites over millennia of human history raises an important evolutionary question: Given the high cost, why does the practice go on? . . .