A castrato is a male soprano, mezzo-soprano, or alto voice produced either by castration of the singer before puberty or one who, because of an endocrinological condition, never reaches sexual maturity.
Castration before puberty (or in its early stages) prevents a boy's larynx from being transformed by the normal physiological events of puberty. As a result, the vocal range of prepubescence (shared by both sexes) is largely retained, and the voice develops into adulthood in a unique way. As the castrato's body grew, his lack of testosterone meant that his epiphyses (bone-joints) did not harden in the normal manner. Thus the limbs of the castrati often grew unusually long, as did the bones of their ribs. This, combined with intensive training, gave them unrivalled lung-power and breath capacity. Operating through small, child-sized vocal cords, their voices were also extraordinarily flexible, and quite different from the equivalent adult female voice, as well as higher vocal ranges of the uncastrated adult male (see soprano, mezzo-soprano, alto, sopranist, countertenor and contralto). Listening to the only surviving recordings of a castrato (see below), one can hear that the lower part of the voice sounds like a "super-high" tenor, with a more falsetto-like upper register above that.
Castrati were rarely referred to as such: the term musico (pl musici) was much more generally used; another synonym was evirato (literally meaning "unmanned").
History of castration
Castration as a means of subjugation, enslavement or other punishment has a very long pedigree, dating back to ancient Sumeria (see also Eunuch). In a Western context, eunuch singers are known to have existed from the early Byzantine Empire. In Constantinople around 400 AD the empress Eudoxia had a eunuch choir-master, Brison, who apparently established the use of castrati in Byzantine choirs. Whether Brison himself was a singer, and whether he had colleagues who were eunuch singers, has not been definitely established. By the ninth 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 by no means clear, though it seems likely that the Spanish tradition of soprano falsettists may have "hidden" castrati (it should be remembered that much of Spain was under Arab domination at various times during the Middle Ages, and that eunuch harem-keepers and the like, almost always taken from conquered populations, were a commonplace of that society: by sheer statistics, some of them are likely to have been singers).
Castrati in the European Classical tradition
Castrati, many of them having Spanish names, first appeared in Italy in the mid-sixteenth century. Alfonso II d'Este, Duke of Ferrara, was an early enthusiast (by 1556). There were castrati in the court chapel at Munich by 1574, where the Kapellmeister (music director) was Orlando di Lasso, and it is likely that Palestrina, director of the choir of St Peter's from 1576 to 1594, would have been keen to emulate his famous contemporary. In 1589, by the bull Cum pro nostri temporali munere, Pope Sixtus V re-organised that choir specifically to include castrati, and in 1599, they were first admitted into the Pope's personal choir of the Sistine Chapel: Pietro Paolo Folignato and Girolamo Rossini (it is likely that others, such as Padre Soto, appointed in 1562, joined earlier under the euphemism "falsettist"). Thus the castrati came to supplant both boys (whose voices broke after only a few years) and falsettists (whose voices were weaker and less reliable) from the top line in such choirs. Women were of course banned by the Pauline dictum mulier taceat in ecclesia ("let your women keep silent in church"; see I Corinthians, ch 14, v 34).
Castrati in opera
Castrati had parts in the earliest operas: in the first performance of Monteverdi's Orfeo (1607) they played subsidiary roles, including that of Euridice. By 1680, however, they had supplanted "normal" male voices in lead roles, and retained their hegemony as primo uomo for about a hundred years; an opera not featuring at least one renowned castrato in a lead part would be doomed to fail. Because of the popularity of Italian opera throughout 18th-century Europe (except France), singers such as Ferri, Farinelli, Senesino and Pacchierotti became the first operatic superstars, earning enormous fees and hysterical public adolation. The strictly hierarchical organisation of opera seria favoured their high voices as symbols of heroic virtue, though they were frequently mocked for their strange appearance and bad acting.
Castration "for music" was an almost totally Italian practice, and under the Catholic church's Canon Law, strictly illegal: it was mutilation, and thus punishable by excommunication. The music historian Charles Burney was sent from pillar to post in search of places where the operation was carried out: "I enquired throughout Italy at what place boys were chiefly qualified for singing by castration, but could get no certain intelligence. I was told at Milan that it was at Venice; at Venice that it was at Bologna; but at Bologna the fact was denied, and I was referred to Florence; from Florence to Rome, and from Rome I was sent to Naples... it is said that there are shops in Naples with this inscription: 'QUI SI CASTRANO RAGAZZI' ("Here boys are castrated"); but I was utterly unable to see or hear of any such shops during my residence in that city."
The training of the boys was rigorous. The regime of one singing school in Rome (c. 1700) consisted of one hour of singing difficult and awkward pieces, one hour practising trills, one hour practising ornamented passaggi, one hour of singing exercises in their teacher's presence and in front of a mirror so as to avoid unnecessary movement of the body or facial grimaces, and one hour of literary study; all this, moreover, before lunch. After, half-an-hour would be devoted to musical theory, another to writing counterpoint, an hour copying down the same from dictation, and another hour of literary study. During the remainder of the day, the young castrati had to find time to practice their harpsichord playing, and to compose vocal music, either sacred or secular depending on their inclination. This demanding schedule meant that, if sufficiently talented, they were able to make a debut in their mid-teens with a perfect technique and a voice of a flexibility and power no woman or ordinary male singer could match.
In the 1720s and 1730s, at the height of the craze for these artificially-preserved voices, it has been estimated that upwards of 4000 boys were castrated annually in the service of art. Many came from poor homes, and were more or less sold by their parents to the church or to a singing-master, in the hope that their child might be successful and lift them from their lowly status in society (this was the case with Senesino). There are, though, records of some young boys asking to be operated on to preserve their voices (e.g. Caffarelli, who was from a wealthy family: his grandmother gave him the income from two vineyards to pay for his studies). Caffarelli was also typical of many castrati in being famous for tantrums on and off-stage, and for amorous adventures with noble ladies. Some, as described by Casanova, preferred gentlemen (noble or otherwise). Modern endocrinology would suggest that the castrati's much-vaunted sexual prowess was more the stuff of legend than reality. Not all castrated boys had successful careers on the operatic stage; the better "also-rans" sang in cathedral or church choirs, while some, trained as they were in acting, may have turned to the straight theatre, or perhaps even prostitution.
Decline
By the late eighteenth century, changes in operatic taste and social attitudes spelled the end for the castrati. They lingered on past the end of the ancien régime (which their style of opera parallels), and two of their number, Pacchierotti and Crescentini, even entranced the iconoclastic Napoleon. The last great operatic castrato was Giovanni Battista Velluti (1781-1861), who performed the last operatic castrato role ever written: Armando in Il Crociato in Egitto by Meyerbeer (Venice, 1824). Soon after this they were replaced definitively as the first men of the operatic stage by the new breed of heroic tenor as incarnated by the Frenchman Gilbert-Louis Duprez, the earliest "king of the high Cs", whose successors are singers like Caruso, Franco Corelli, and Luciano Pavarotti.
After the reunification of Italy in 1870, castration for musical purposes was made officially illegal (the new Italian state had adopted a French legal code which expressly forbade the practice). In 1878, Pope Leo XIII prohibited the hiring of new castrati by the church: only in the Sistine Chapel and in other papal basilicas in Rome did a few castrati linger. A group photo of the Sistine Choir taken in 1898 shows that by then only six remained (plus the Direttore Perpetuo, the fine soprano castrato Domenico Mustafà), and in 1902 a ruling was extracted from Pope Leo that no further castrati should be admitted. The official end to the castrati came on St. Cecilia's Day, 22 November 1903, when the new pope, Pius X, issued his motu proprio, Tra le Sollecitudini ('Amongst the Cares'), which contained this instruction: "Whenever . . . it is desirable to employ the high voices of sopranos and contraltos, these parts must be taken by boys, according to the most ancient usage of the Church." The last Sistine castrato to survive was Alessandro Moreschi, the only castrato to have made recordings. On Moreschi, critical opinion varies between those who think him mediocre and only interesting as an historical record of the castrato voice, and others who regard him as a fine singer, judged on the practice and taste of his own time. He retired officially in March 1913, and died in 1922.