A cappella (, also , ; ) music is a performance by a singer or a singing group without instrumental accompaniment, or a piece intended to be performed in this way. The term a cappella was originally intended to differentiate between Renaissance polyphony and Baroque concertato musical styles. In the 19th century, a renewed interest in Renaissance polyphony, coupled with an ignorance of the fact that vocal parts were often doubled by instrumentalists, led to the term coming to mean unaccompanied vocal music. The term is also used, rarely, as a synonym for alla breve. Early history A cappella could be as old as humanity itself. Research suggests that singing and vocables may have been what early humans used to communicate before the invention of language. The earliest piece of sheet music is thought to have originated from times as early as 2000 B.C. while the earliest that has survived in its entirety is from the first century A.D.: a piece from Greece called the Seikilos epitaph. Religious origins A cappella music was originally used in religious music, especially church music as well as anasheed and zemirot. Gregorian chant is an example of a cappella singing, as is the majority of secular vocal music from the Renaissance. The madrigal, up until its development in the early Baroque into an instrumentally accompanied form, is also usually in a cappella form. The Psalms note that some early songs were accompanied by string instruments, though Jewish and Early Christian music was largely a cappella; the use of instruments has subsequently increased within both of these religions as well as in Islam. Christian The polyphony of Christian a cappella music began to develop in Europe around the late 15th century AD, with compositions by Josquin des Prez. The early a cappella polyphonies may have had an accompanying instrument, although this instrument would merely double the singers' parts and was not independent. By the 16th century, a cappella polyphony had further developed, but gradually, the cantata began to take the place of a cappella forms. Sixteenth-century a cappella polyphony, nonetheless, continued to influence church composers throughout this period and to the present day. Recent evidence has shown that some of the early pieces by Palestrina, such as those written for the Sistine Chapel, were intended to be accompanied by an organ "doubling" some or all of the voices. Such is seen in the life of