The practice of castrating humans began in Asia, where eunuchs served as the chamberlain of a harem. It reached its epitome under the Byzantine Empire in Constantinople and was subsequently employed by the Ottoman sultans. The practice of using eunuchs in choirs can also be traced to Constantinople.
Castrating a man in ancient culture lowered his social standing. Since he had no wife, offspring or in-laws, the eunuch was considered less influenced by outside forces. The emperor could have the castrated male put to death at will with no lasting consequences.
Castrated males served in the courts of the pharaoh through the Lagid dynasty, ending with Cleopatra. In China, the practice of castrating humans served as a means of punishment and a way of finding employment. When the Ming dynasty ended, more than 70,000 castrated men were employed by the emperor, with many serving outside the palace.
In some cultures, young boys were castrated before developing their secondary sex characteristics in order to maintain their childlike voice. While these castrati were trained in music, there was no guarantee that castration would cause them to maintain the voice. The decision had to be made before the boy was old enough to make the conscious choice to sacrifice his sexual potency for a singing voice. The last eunuch of the Sistine chapel died in 1922.