For the music geek, there‘s nothing like when a song you know and love suddenly offers up a backstory that you‘d never imagined, a tune that you think is originated by an iconic rock act that actually had its beginnings elsewhere, sometimes in a different genre.

That musical archaeology was the bedrock of classic rock. Musicians constantly sifted through the past, remixing classics with big distorted guitars, dramatic arrangements and their own unique signature performance that brought the music to a whole new demographic. Here are a dozen recordings that had origins that were often much earlier than you realized.

“Black Betty”—Ram Jam (1977)

This recording owes its roots to an older American work song. Blues icon Lead Belly released his version in 1939, following up on earlier field recordings of the song from prison crews. This electric treatment made the New York City band a worldwide late ‘70s one-hit wonder.

“I Don’t Need No Doctor”—Humble Pie (1971)

The English rock band adapted this song into a scorching anthem on their live album, Performance: Rockin’ the Fillmore. Recorded in 1966 by Ray Charles and written by Nick Ashford, Valerie Simpson and Jo Armstead, here Steve Marriott‘s burning voice and the group‘s propulsive rhythm section dropped the song right into the middle of early-’70s blues-rock. The single edit gave them a modest U.S. chart hit.

“Kentucky Woman”—Deep Purple (1968)

Prior to their heavy rock masterpieces, the group had a hit with this lively cover. The song was written and originally recorded by Neil Diamond in his easygoing style, just a year earlier. This rendition spiced it up with whirling keyboards and the bombast that gave a prelude to their signature sound.

“Bad Case of Loving You (Doctor, Doctor)”—Robert Palmer (1979)

It was the suave singer’s self-produced version of the song that really went for gold—reaching #14 on the Billboard Hot 100 to become one of his most popular songs Stateside. Its songwriter, Moon Martin, originally recorded it just one year earlier. It didn’t chart, leading audiences to assume Palmer’s version was a brand new song. His take offered a rock veneer that made it more radio-friendly. [Many of Palmer’s recordings are available here.]

‘‘Train Kept A-Rollin’’—The Yardbirds (1965)

This blues standard was re-recorded into a guitar-based rock anthem that would inspire future generations of guitarists. It was first recorded in 1951 by rhythm and blues singer Tiny Bradshaw and then five years later by Johnny Burnette and His Rock and Roll Trio. When you have a rock god guitarist like Jeff Beck as part of your lineup, the Yardbirds’ electrified rendition of the song becomes epic. In 1966, with Jimmy Page now in the band’s lineup, they performed it (under the title “Stroll On”) for Michelangelo Antonioni’s 1966 British Mod classic film Blow-Up.

“Police on My Back”—The Clash (1980)

The track was written by Eddy Grant, who recorded it with his band, the Equals, in 1967. The Clash’s toe-tapping cover version, from their sprawling three-LP set, Sandinista!, was described by diffuser.com as “transform[ing] the mid-paced soul-pop song into a charged-up, full-powered rocker.” Others called it “a punk anthem at a time of political and social repression” and their “most full-throated rock song since ‘I Fought The Law.’”

“Tobacco Road”—The Nashville Teens (1964)

The blues song was written by American singer-songwriter John D. Loudermilk (“Indian Reservation,” “Then You Can Tell Me Goodbye,” among many others). His original version was first recorded in 1959 and released in 1960. Several years later, the track was given a grittier rock arrangement by this British rock group, and became a solid hit in the U.K., U.S. and Canada. The band‘s raw performance turned it into a rock standard of the ’60s.

“Piece of My Heart”—Janis Joplin (1968)

The song, best described as a soulful cry of hurt, was written by Jerry Ragovoy and Bert Berns and originally recorded in 1967 by Erma Franklin, reaching #10 on the R&B chart and becoming a modest pop hit. One year later, one of rock’s greatest vocalists of the late ’60s recorded this with Big Brother and the Holding Company. It was etched into rock history when she and her Kozmic Blues Band performed it at Woodstock in 1969.

“Respect”—Aretha Franklin (1967)

Otis Redding’s 1965 single of his own song achieved modest success, reaching #4 on the R&B chart and #35 on the Hot 100. But the Queen of Soul‘s recording two years later thoroughly overshadowed that and became her only #1 solo pop hit—yes, you read that correctly—thanks to her phenomenal performance, the top-notch musicianship (including many of Muscle Shoals’ finest, though it was recorded in New York) and Jerry Wexler’s production. The song won Aretha two Grammys and became one of the anthems of the era. [Many of her classic recordings are available here.]

“Mad World”—Michael Andrews and Gary Jules (2001)

Top 40 listeners in the U.S. would have been unaware of Tears For Fears’ 1982 original. Though it reached #3 in the U.K., it was ignored Stateside. More than two decades later, this slowed-down cover topped the U.K. year-end Singles Chart in 2003 (It was also featured in the 2001 movie Donnie Darko.) Whereas the original was synthesized with plenty of drums, the haunting, later version was minimalist and acoustic; not a lot of accompaniment, just some piano chords, a cello Mellotron and minimal electric piano and vocoder on the chorus. Its memorable video was shot from a school’s rooftop.

“I Love Rock ’n Roll”—Joan Jett & the Blackhearts (1981)

Her version was a #1 single on the Billboard Hot 100 in 1982, where it stayed for seven weeks, and topped many charts worldwide. First recorded in 1975 by the Arrows, the glam rock band‘s version received limited exposure. The song gained widespread recognition after being covered by Jett for her solo album of the same name, after she had seen the original performed years’ earlier while on tour in the U.K. with the Runaways.

“Bette Davis Eyes”—Kim Carnes (1981)

The great cover topped the Hot 100 for nine weeks in 1981, becoming one of the most successful songs of the year. It was recorded earlier in 1974 by its co-writer Jackie De Shannon in a more sensitive piano-based version. Carnes’ version won the Song of the Year and Record of the Year awards at the 1982 Grammy Awards. Waddy Wachtel, who played background guitar on the recording, told Best Classic Bands, “Everything you hear on that record is live. Every note of it. Kim’s vocal. Every sound. It all went down when we performed it. I [told producer Val Garay], ‘I bet you this is a smash. This is a f*cking smash.’ And it was. Val used the monitor mix. It was great. We just ‘had’ it. It happens sometimes.”