Blues has evolved from the unaccompanied vocal music and oral traditions of slaves imported from West Africa and rural Africans into a wide variety of styles and subgenres, with regional variations across the United States. Although blues (as it is now known) can be seen as a musical style based on both European harmonic structure and the African call-and-response tradition that transformed into an interplay of voice and guitar, the blues form itself bears no resemblance to the melodic styles of the West African griots. Additionally, there are theories that the four-beats-per-measure structure of the blues might have its origins in the Native American tradition of pow wow drumming. Some scholars identify strong influences on the blues from the melodic structures of certain West African musical styles of the savanna and sahel. Lucy Durran finds similarities with the melodies of the Bambara people, and to a lesser degree, the Soninke people and Wolof people, but not as much of the Mandinka people. Gerard Kubik finds similarities to the melodic styles of both the west African savanna and central Africa, both of which were sources of enslaved people.
No specific African musical form can be identified as the single direct ancestor of the blues. However the call-and-response format can be traced back to the music of Africa. That blue notes predate their use in blues and have an African origin is attested to by "A Negro Love Song", by the English composer Samuel Coleridge-Taylor, from his African Suite for Piano, written in 1898, which contains blue third and seventh notes.
The Diddley bow (a homemade one-stringed instrument found in parts of the American South sometimes referred to as a jitterbug or a one-string in the early twentieth century) and the banjo are African-derived instruments that may have helped in the transfer of African performance techniques into the early blues instrumental vocabulary. The banjo seems to be directly imported from West African music. It is similar to the musical instrument that griots and other Africans such as the Igbo played (called halam or akonting by African peoples such as the Wolof, Fula and Mandinka). However, in the 1920s, when country blues began to be recorded, the use of the banjo in blues music was quite marginal and limited to individuals such as Papa Charlie Jackson and later Gus Cannon.
Blues music also adopted elements from the "Ethiopian airs", minstrel shows and Negro spirituals, including instrumental and harmonic accompaniment. The style also was closely related to ragtime, which developed at about the same time, though the blues better preserved "the original melodic patterns of African music"
