<Tr> <Td> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> </Td> </Tr> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> <P> Blues is a music genre and musical form originated by African Americans in the Deep South of the United States around the end of the 19th century . The genre developed from roots in African musical traditions, African - American work songs, spirituals, and the folk music of white Americans of European heritage . Blues incorporated spirituals, work songs, field hollers, shouts, chants, and rhymed simple narrative ballads . The blues form, ubiquitous in jazz, rhythm and blues and rock and roll, is characterized by the call - and - response pattern, the blues scale and specific chord progressions, of which the twelve - bar blues is the most common . Blue notes (or "worried notes"), usually thirds or fifths flattened in pitch, are also an essential part of the sound . Blues shuffles or walking bass reinforce the trance - like rhythm and form a repetitive effect known as the groove . </P> <P> Blues as a genre is also characterized by its lyrics, bass lines, and instrumentation . Early traditional blues verses consisted of a single line repeated four times . It was only in the first decades of the 20th century that the most common current structure became standard: the AAB pattern, consisting of a line sung over the four first bars, its repetition over the next four, and then a longer concluding line over the last bars . Early blues frequently took the form of a loose narrative, often relating the racial discrimination and other challenges experienced by African - Americans . </P>

What were the roots of the blues aesthetic
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