Source Material: Napalm Death, 'Scum'
There aren't too many genres where you can pinpoint one particular album as the precise starting point, but with the extreme-metal sub-style long known as "grindcore," there's not much room for argument. Napalm Death's debut album, Scum, was 28 songs recorded nine months apart by two almost entirely different lineups of the British band (only common denominator: inhumanly rapid-fire blastbeat-popularizing drummer Mick Harris, who is said to have given grindcore its name). The album was then released in 1987 to punters who couldn't quite tell if this was a novelty act pulling their leg. On the first side which followed on the heels of six N.D. demos dating back to 1982 and which was originally slated to be half of a split LP with another band one of the 12 tracks lasts almost four minutes, but the last one, "You Suffer," checks in at a mere 1.316 seconds, making the Guinness Book of World Records for its brevity. The 16 cuts on Side 2 range in length from 16 seconds ("Common Enemy") to a comparatively almost symphonic 1:34, for "M.A.D."
First-side Napalm guitarist Justin Broadrick went on to perform more industrialized and ambient metal in Head of David, Godflesh, Jesu and sundry techno-dub projects; Harris and first-side vocalist-bassist Nick Bullen made experimental electronica in Scorn; second-side singer Lee Dorrian managed a decent doom-metal career in Cathedral; second-side guitarist Bill Steer got nasty in Carcass, then more straightforwardly rock in Firebird and Gentleman's Pistols. So it's not like Scum is the best music any of them ever made. It's definitely not the most listenable. But, at least for the hordes who care about grindcore, it's probably the most historically significant.
It also got to No. 7 on the U.K. indie chart, if you're keeping score. But given all that, the album still wasn't without precedent, at least as far as squeezing death-thrash horrificness into compact crusty-slamdance snippets. So while it's probably true that grindcore turned the punk/metal hybrid into something even faster and shorter, it's not like Napalm Death were the first people to have the idea in a sense, they just took electro-shock innovations that had been setting mohawks on fire for several years and codified them into a genre requirement. In fact, on the 2004 album Leaders Not Followers, Pt. 2 (preceded five years earlier by a similar EP), N.D. covered a truckload of songs, many of them by bands who had somehow anticipated grindcore before it had a name. Hence, here's some probable Scum source material, acknowledged and/or not.