Field hollers, cries and hollers of the enslaved people and later sharecroppers working in cotton fields, prison chain gangs, railway gangs (gandy dancers) or turpentine camps were the precursor to the call and response of African American spirituals and gospel music, to jug bands, minstrel shows, stride piano, and ultimately to the blues, rhythm and blues, jazz and African American music in general. Spirituals were primarily expressions of religious faith. Some may also have served as socio-political protests veiled as assimilation to white American culture. They originated among enslaved Africans in the United States. Slavery was introduced to the British colonies in the early 17th century, and enslaved people largely replaced indentured servants as an economic labor force during the 17th century. In the United States, these people would remain in bondage for the entire 18th century and much of the 19th century. Most were not fully emancipated until the ratification of the Thirteenth Amendment to the Constitution in 1865. Enslaved people were forbidden to speak their native languages, and were generally converted to Christianity. With narrow vocabularies, enslaved people would use the words they did know to translate biblical information and facts from their other sources into song. While some slave owners believed that Christian slaves would be more docile, others came to feel that stories of Moses leading the Israelites out of bondage were counterproductive. Forced conversion only worked to a point since church attendance might be required, but control could not extend to thoughts and feelings. Some enslaved people became Christians voluntarily, either because it helped them endure hardships or because membership may have offered other benefits. Many of the enslaved people turned towards the Baptist or Methodist churches. In some places enslaved Africans were permitted, or even encouraged, to hold their own prayer meetings. Because they were unable to express themselves freely in ways that were spiritually meaningful to them, religious services were, at times, the only place enslaved people could legitimately congregate, socialize, and safely express feelings. During these meetings, worshipers would sing, chant, dance and sometimes enter ecstatic trances. Along with spirituals, shouts also emerged in the Praise Houses. Shouts begin slowly with the shuffling of feet and clapping of hands (but the feet never cross because that was seen as dancing, which was forbidden within the church). Drums were used as they had been in Africa, for communication. When the connection between drumming, communication, and resistance was eventually made drums were forbidden. Enslaved people introduced a number of new instruments to America: the bones, body percussion, and an instrument variously called the bania, banju, or banjar, a precursor to the banjo but without frets.