Rhythm and blues
Afro-Cuban rhythmic influence

African American music began incorporating Afro-Cuban rhythmic motifs in the 1800s with the popularity of the Cuban contradanza (known outside of Cuba as the habanera). The habanera rhythm can be thought of as a combination of tresillo and the backbeat.

For the more than a quarter-century in which the cakewalk, ragtime and proto-jazz were forming and developing, the Cuban genre habanera exerted a constant presence in African American popular music. Jazz pioneer Jelly Roll Morton considered the tresillo/habanera rhythm (which he called the Spanish tinge) to be an essential ingredient of jazz. There are examples of tresillo-like rhythms in some African American folk music such as the hand-clapping and foot-stomping patterns in ring shout, post-Civil War drum and fife music, and New Orleans second line music. Wynton Marsalis considers tresillo to be the New Orleans "clave" (although technically, the pattern is only half a clave). Tresillo is the most basic duple-pulse rhythmic cell in Sub-Saharan African music traditions, and its use in African American music is one of the clearest examples of African rhythmic retention in the United States. The use of tresillo was continuously reinforced by the consecutive waves of Cuban music, which were adopted into North American popular culture. In 1940 Bob Zurke released "Rhumboogie", a boogie-woogie with a tresillo bass line, and lyrics proudly declaring the adoption of Cuban rhythm:

Harlem's got a new rhythm, man it's burning up the dance floors because it's so hot! They took a little rhumba rhythm and added boogie-woogie and now look what they got! Rhumboogie, it's Harlem's new creation with the Cuban syncopation, it's the killer! Just plant your both feet on each side. Let both your hips and shoulder glide. Then throw your body back and ride. There's nothing like rhumbaoogie, rhumboogie, boogie-woogie. In Harlem or Havana, you can kiss the old Savannah. It's a killer!

Although originating in the metropolis at the mouth of the Mississippi River, New Orleans blues, with its Afro-Caribbean rhythmic traits, is distinct from the sound of the Mississippi Delta blues. In the late 1940s, New Orleans musicians were especially receptive to Cuban influences precisely at the time when R&B was first forming. The first use of tresillo in R&B occurred in New Orleans. Robert Palmer recalls:

New Orleans producer-bandleader Dave Bartholomew first employed this figure (as a saxophone-section riff) on his own 1949 disc "Country Boy" and subsequently helped make it the most over-used rhythmic pattern in 1950s rock 'n' roll. On numerous recordings by Fats Domino, Little Richard and others, Bartholomew assigned this repeating three-note pattern not just to the string bass, but also to electric guitars and even baritone sax, making for a very heavy bottom. He recalls first hearing the figure – as a bass pattern on a Cuban disc.

In a 1988 interview with Palmer, Bartholomew (who had the first R&B studio band), revealed how he initially superimposed tresillo over swing rhythm:

I heard the bass playing that part on a 'rumba' record. On 'Country Boy' I had my bass and drums playing a straight swing rhythm and wrote out that 'rumba' bass part for the saxes to play on top of the swing rhythm. Later, especially after rock 'n' roll came along, I made the 'rumba' bass part heavier and heavier. I'd have the string bass, an electric guitar and a baritone all in unison.

Bartholomew referred to the Cuban son by the misnomer rumba, a common practice of that time. Fats Domino's " Blue Monday ", produced by Bartholomew, is another example of this now classic use of tresillo in R&B. Bartholomew's 1949 tresillo-based "Oh Cubanas" is an attempt to blend African American and Afro-Cuban music. The word mambo, larger than any of the other text, is placed prominently on the record label. In his composition "Misery", New Orleans pianist Professor Longhair plays a habanera-like figure in his left hand. The deft use of triplets is a characteristic of Longhair's style.

Gerhard Kubik notes that with the exception of New Orleans, early blues lacked complex polyrhythms, and there was a "very specific absence of asymmetric time-line patterns (key patterns) in virtually all early-twentieth-century African American music... only in some New Orleans genres does a hint of simple time line patterns occasionally appear in the form of transient so-called 'stomp' patterns or stop-time chorus. These do not function in the same way as African timelines." In the late 1940s, this changed somewhat when the two-celled timeline structure was brought into the blues. New Orleans musicians such as Bartholomew and Longhair incorporated Cuban instruments, as well as the clave pattern and related two-celled figures in songs such as "Carnival Day", (Bartholomew 1949) and "Mardi Gras In New Orleans" (Longhair 1949). While some of these early experiments were awkward fusions, the Afro-Cuban elements were eventually integrated fully into the New Orleans sound.

Robert Palmer reports that, in the 1940s, Professor Longhair listened to and played with musicians from the islands and "fell under the spell of Perez Prado's mambo records." He was especially enamored with Afro-Cuban music. Michael Campbell states: "Professor Longhair's influence was... far-reaching. In several of his early recordings, Professor Longhair blended Afro-Cuban rhythms with rhythm and blues. The most explicit is 'Longhair's Blues Rhumba,' where he overlays a straightforward blues with a clave rhythm." Longhair's particular style was known locally as rumba-boogie. In his "Mardi Gras in New Orleans", the pianist employs the 2–3 clave onbeat/offbeat motif in a rumba boogie " guajeo ".

The syncopated, but straight subdivision feel of Cuban music (as opposed to swung subdivisions) took root in New Orleans R&B during this time. Alexander Stewart states that the popular feel was passed along from "New Orleans—through James Brown's music, to the popular music of the 1970s," adding: "The singular style of rhythm & blues that emerged from New Orleans in the years after World War II played an important role in the development of funk. In a related development, the underlying rhythms of American popular music underwent a basic, yet generally unacknowledged transition from a triplet or shuffle feel to even or straight eighth notes. Concerning the various funk motifs, Stewart states that this model "... is different from a time line (such as clave and tresillo) in that it is not an exact pattern, but more of a loose organizing principle."

Johnny Otis released the R&B mambo "Mambo Boogie" in January 1951, featuring congas, maracas, claves, and mambo saxophone guajeos in a blues progression. Ike Turner recorded "Cubano Jump" (1954) an electric guitar instrumental, which is built around several 2–3 clave figures, adopted from the mambo. The Hawketts, in " Mardi Gras Mambo " (1955) (featuring the vocals of a young Art Neville), make a clear reference to Perez Prado in their use of his trademark "Unhh!" in the break after the introduction.

Ned Sublette states: "The electric blues cats were very well aware of Latin music, and there was definitely such a thing as rhumba blues; you can hear Muddy Waters and Howlin' Wolf playing it." He also cites Otis Rush, Ike Turner and Ray Charles, as R&B artists who employed this feel.

The use of clave in R&B coincided with the growing dominance of the backbeat, and the rising popularity of Cuban music in the U.S. In a sense, clave can be distilled down to tresillo (three-side) answered by the backbeat (two-side).

The " Bo Diddley beat " (1955) is perhaps the first true fusion of 3–2 clave and R&B/rock 'n' roll. Bo Diddley has given different accounts of the riff's origins. Sublette asserts: "In the context of the time, and especially those maracas, 'Bo Diddley' has to be understood as a Latin-tinged record. A rejected cut recorded at the same session was titled only 'Rhumba' on the track sheets." Johnny Otis 's "Willie and the Hand Jive" (1958) is another example of this successful blend of 3–2 claves and R&B. Otis used the Cuban instruments claves and maracas on the song.

Afro-Cuban music was the conduit by which African American music was "re-Africanized", through the adoption of two-celled figures like clave and Afro-Cuban instruments like the conga drum, bongos, maracas and claves. According to John Storm Roberts, R&B became the vehicle for the return of Cuban elements into mass popular music. Ahmet Ertegun, producer for Atlantic Records, is reported to have said that "Afro-Cuban rhythms added color and excitement to the basic drive of R&B." As Ned Sublette points out though: "By the 1960s, with Cuba the object of a United States embargo that still remains in effect today, the island nation had been forgotten as a source of music. By the time people began to talk about rock and roll as having a history, Cuban music had vanished from North American consciousness."
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