Many analysts have developed theories over how it all came about, how what came to be known as Rock & Roll was born, what details and events triggered it. It seems to me clear that when they added rythm to blues, (with jazz sub-genres ragtime and boogie-woogie, et al), it could only develop into this (some point out the native american indian tom-tom beat as a clear influence, others the country-western beat, which in turn derived fron the horse gallop). But rather than trying to develop one more theory or to account events (more than enough accounts are out there), I will present directly, relevant illustrative examples.
Elvis Presley is of course the main influence, but there were others, with a place of distinction for The Platters. Chuck Berry introduced Johnny B. Good to the world, and Bill Haley & The Comets rocked kids around the clock - suddenly somewhere along the way, someone plugged a guitar into an electric socket, and it was the Rock & Roll era!
Post-note: It seems that that someone is credited to have been none other than Les Paul, a jazz musician playing around with electronics, who came up with the idea of plugging-in the acoustic guitar, fusion country-western with jazz and turn-up with a new sound in the early 50's, with several hits on the charts, with help from his wife Mary Ford's vocal talents.
According to Wiki, "...[Les Paul] is a pioneer in the development of the solid-body electric guitar which 'made the sound of rock and roll possible.' "
It's not rock&roll yet, but you can hear "pre-form" samples of what later on would become typical rock guitar riffs.
"How High The Moon" - Les Paul & Mary Ford
(1951 original recording)
Music without words
To "voice" music, that is, to use the vocal system (from lungs, through throat, to mouth) as a musical instrument, words - lyrics - are most often used. But humming, or "lah-lah-lah-ing", are of course, almost instinctively used, since times immemorial. With Jazz came "scat" and with 50's rock came "doo-wop": an official sub-genre. The "bop-shoo-wops", the "shang-alang-alangs" marked an era, or at least, the collective memory of a generation of teenagers, as illustrated in the doo-wop nostalgic Carpenters' hit "Ev'ry Sha La La" (maybe not the song's official title, but the one that it's best known as). One thing's for sure: who ever it was that put the bop in the bop-shoo-bop, should be thanked for it!
"If you tried to give rock&roll another name, you might call it 'Chuck Berry'."
- John Lennon
Links to audio:
Danny & the Juniors - At The Hop
Frankie Lymon & The Teenagers - Why Do Fools Fall in Love
Marty Robbins - A White Sport Coat And A Pink Carnation
Jerry Lee Lewis - Great Balls Of Fire
Sam Cooke - Don't Know Much About History or Biology
The Platters - Only You
The Platters - Smoke Gets In Your Eyes
Ben E. King - Stand By Me
Del Shannon - Runaway
The Marcels - Blue Moon