On his eighth day of life, a newborn Jewish boy is taken to his family’s synagogue. His mother hands him to the kvatters, who place him in the Chair of Elijah for his bris. So begins the Jewish ritual of circumcision, which tradition says seals Abraham’s covenant with God as described in Genesis 17. A Muslim family teaches their sons that the Prophet Muhammad was born without a foreskin. To emulate the prophet, Muslim boys are circumcised, usually in a hospital, sometime before the age of 12. People of many cultures and religions, including Jews, Muslims, ancient Egyptians and tribal people around the world, have practiced male circumcision for centuries. No one knows for sure exactly when it started, but some historians say it may have begun as a puberty rite among Australian aboriginal tribes in 10,000 BC. Later, tribes in Northern East Africa and the Arabian Peninsula would adopt the practice. Circumcision has fallen in and out of favor throughout history, but the story of its introduction to nonreligious, Western populations is interesting. Outside of Jewish and Muslim communities, it was uncommon to routinely circumcise boys until the late 19th and early 20th centuries, when doctors began promoting it as a way to prevent masturbation and some diseases.