Most folk agree that hip hop or rap music grew up in New York, during the early 1970s, when MCs improvised on the mic, entertaining the crowd as they waited for the next DJ to take over the booth. Though certainly there are earlier examples, many point to the 1979 commercial release, "Rapper's Delight" by The Sugarhill Gang, as one of the first.
But how come no one ever gives any credit to Led Zeppelin? Way back in 1973, the released the song "The Ocean" on their Houses of the Holy album, which featured their drummer, John Bonham, rapping the following in silence, as he Led up to opening bar of the song:
"We've done four already but now we're steady and then they went: One, two, three, four"¦"
I'd like to challenge someone to find an earlier recorded example of rap. I'm sure it exists, but I think it would be cool if one of your readers sent in a link, or a reference.
Even if it doesn't deserve singling out for being the first recorded rap on record, Zeppelin's "The Ocean" is surely one of the only hit songs ever written in 15/16. Common time signature in pop or rock music is, of course, 4/4, or 4 beats to the bar. 15/16, which is missing one 16th note per bar, is extremely hard to dance to, as you'll hear if you play the YouTube clip. Listen for it in the hard rockin' opening.
"The Ocean" also had a big influence on a couple other rappers, as well. Check it: The Beastie Boys sampled the song on "She's Crafty" and more recently, Linkin Park's Mike Shinoda sampled it in "Dolla", a song he recorded with his other band, Fort Minor.