Eunuch is a more general term, since historically many eunuchs were castrated after puberty and thus the castration had no impact on their voices.Castration as a means of subjugation, enslavement or other punishment has a very long history, dating back to ancient Sumer.By the 9th century, eunuch singers were well-known (not least in the choir of Hagia Sophia) and remained so until the sack of Constantinople by the Western forces of the Fourth Crusade in 1204.Their fate from then until their reappearance in Italy more than three hundred years later is not clear.In a Western context, eunuch singers are known to have existed from the early Byzantine Empire.In Constantinople around AD 400 the empress Aelia Eudoxia had a eunuch choir-master, Brison, who may have established the use of castrati in Byzantine choirs, though whether Brison himself was a singer and whether he had colleagues who were eunuch singers is not certain.A castrato (Italian, plural: castrati) is a type of classical male singing voice equivalent to that of a soprano, mezzo-soprano, or contralto.The voice is produced by castration of the singer before puberty, or it occurs in one who, due to an endocrinological condition, never reaches sexual maturity.
In 1589, by the bull Cum pro nostro pastorali munere, Pope Sixtus V re-organised the choir of St Peter's, Rome specifically to include castrati. Reader, if of the City, thou mayest probably have seen in the Fields of Islington or Mile-End or, If thou art in the environs of St James', thou must have observed in the Park with what Ease and Agility a cow, heavy with calf, has rose up at the command of the Milk-woman's foot: thus from the mossy bank sprang the DIVINE FARINELLI.
There were certainly castrati in the Sistine Chapel choir in 1558, although not described as such: on 27 April of that year, Hernando Bustamante, a Spaniard from Palencia, was admitted (the first castrati so termed who joined the Sistine choir were Pietro Paolo Folignato and Girolamo Rossini, admitted in 1599).
Surprisingly, considering the later French distaste for castrati they certainly existed in France at this time also, being known of in Paris, Orléans, Picardy and Normandy, though they were not abundant: the King of France himself had difficulty in obtaining them.
Prepubescent castration for this purpose diminished greatly in the late 18th century and was made illegal in Italy in 1870.
As the castrato's body grew, his lack of testosterone meant that his epiphyses (bone-joints) did not harden in the normal manner.Although female roles were performed by castrati in some of the papal states, this was increasingly rare; by 1680, they had supplanted "normal" male voices in lead roles, and retained their position as primo uomo for about a hundred years; an Italian opera not featuring at least one renowned castrato in a lead part would be doomed to fail. I enquired throughout Italy at what place boys were chiefly qualified for singing by castration, but could get no certain intelligence.