All metal -- all music, period -- synthesizes stuff that came before, but some is a synthesis of more stuff that came before. The more music a band or album mixes up, the more this "Source Material" concept makes sense; i.e., I keep thinking I should do one of these on Slayer's Reign in Blood sometime, but who the heck influenced Slayer? Venom, I guess. Sabbath, sure, but Sabbath influenced everybody. Could maybe come up with a couple more, but since Slayer basically only do one thing, 15 Slayer-influencing albums would be tough.
But then there are bands like Faith No More, and specifically their platinum 1989 breakthrough, The Real Thing, where eclecticism is the whole point, so 15 barely seems like enough. From their Wiki page: "The band is well known for combining elements of heavy metal with funk, hip-hop, progressive rock, alternative rock, hardcore punk, polka, easy listening, jazz, samba, bossa nova, hard rock, pop, soul, gospel and lounge music." I'm not sure I buy every single one of those (sounds that alt metal people refer to as "jazz" are often questionable), but that's quite a list, and it leaves out goth, dub and Middle Eastern music, which all probably show up in the stew as well.
The San Francisco quintet had been around in some form or another, changing its lineup constantly, since 1981. Early singers included Courtney Love and a guy who had done ironic rap and hardcore versions of The Grateful Dead's "Truckin'" in The Pop-O-Pies. F.N.M.'s first two LPs -- 1985's We Care a Lot and 1987's Introduce Yourself -- would have more likely been classified as "college radio rock" or "modern rock" or "funk-punk" than metal; "We Care a Lot" itself was a college-radio novelty hit. On The Real Thing, Mike Patton, he of the theoretically experimental art/joke band Mr. Bungle, replaced Chuck Mosley as frontman, and it took forever for mainstream metalheads to notice. The album was released in June 1989 but didn't enter the Billboard 200 until February 1990; the first single, "From Out of Nowhere," went right back to nowhere, and the second, "Epic," didn't chart until June 1990, a full year after the album came out.
But once the "Epic" video exploded, with its flopping fish out of water and piano (literally, in the latter case) on MTV -- sort of like Guns 'N Roses' "Sweet Child O' Mine" had exploded a year post-album-release two years before; sort of like Nirvana's "Smells Like Teen Spirit" would take over the video channel out of the blue a year later -- everything changed. "Epic" wound up a Top 10 single; The Real Thing got to No. 11, stayed on the chart for 60 weeks, moved a million units in U.S., and did really well in Australia, Canada and across Europe to boot.
Superstardom proved fleeting, though. Their next album, 1992's probably even more convoluted Angel Dust, went Top 10 in America but was off the charts within 20 weeks; two subsequent studio albums had even less staying power, and actually had more luck overseas (especially Down Under) than at home. But The Real Thing and its hits continue to show up on best-metal-ever surveys, and "Epic" gets remembered on one-hit-wonder lists as well. Affection never really faded.
Anyway, below you'll find an attempt to chart some of the music that probably paved the way for the album's prog/metal/rap/funk/whatever hybrid. A few of these bands (fellow Californians Fishbone and Jane's Addiction; New Yorkers Living Colour and The Beastie Boys; Texans The Butthole Surfers) typify the sort of genre mixing-and-matching happening at metal's more idiosyncratic edges through the hair-glam and early thrash years, often under the radar but increasingly surfacing by the '80s' end. (It's worth reiterating here that the myth of Nirvana single-handedly sending hair metal off to pasture has always been bunk; the glammy stuff was already on its way out, as the pre-"Teen Spirit" MTVisibility of a bunch of these bands, and others such as the biracial and comparably artsy-fartsy trio King's X, attests.)
Four other albums below contain songs Faith No More wound up covering: Black Sabbath's "War Pigs" on non-vinyl editions of The Real Thing itself; Deep Purple's "Highway Star," John Barry's "Midnight Cowboy" theme and The Commodores' "Easy" not long after. And what's left is a hodgepodge: '70s art rock (Queen, Pink Floyd, Genesis); turn-of-the-'80s New Waviness (Tubes, Public Image Ltd.); mid-'80s funk-rock (Prince). Several more artists streamable on Napster maybe could have been included (Alice Cooper, Sparks, Steely Dan, Brian Eno, Funkadelic, Tom Waits, Killing Joke, Talking Heads, Devo, Red Hot Chili Peppers, The Cure, "Weird Al" Yankovic, Run-D.M.C.?), not to mention others not so much streamable here (Frank Zappa, Led Zeppelin, King Crimson, Metallica, solo Peter Gabriel?). But these 15 ought to provide a useful grid to start connecting the dots -- as Faith No More already did. "You want it all, but you can't have it," their most famous song went; their music tried hard to prove just the opposite.