A decade ago it would’ve been hard to imagine San Francisco rapper-singer-activist Michael Franti creating a melodic, richly arranged tour de force like Stay Human (Six Degrees), the brand-new third album from his R & B collective, Spearhead. In the early 90s, as half of the Disposable Heroes of Hiphoprisy, he was hobbled by the band’s minimalist beats and his own unwieldy combination of literate agitprop and rap–not even his forceful baritone could smooth out the clunky rhetoric in his lyrics, and in the end, anarchist booksellers might’ve been the only ones who adopted lines like “Exxon and on and on and on” and “Hypocrisy is the greatest luxury” as hip-hop quotables. Franti’s politics still sometimes get the better of him, especially when he doesn’t set them to music: the running narrative between Stay Human’s songs, which casts Franti and Nazelah Jamison as community-radio hosts who help expose a corrupt governor, is an embarrassing left-wing martyr fantasy (after the bad guy knowingly lets an innocent woman be executed, the FBI storms our heroes’ studio). But his lyrics have grown more fluent–“Disregard the mainstream, media distorted / Whoop! Whoop! / We comin’ listener supported” might not hit too hard on the page, but booming out over a deep reggae groove it evokes dub poet Linton Kwesi Johnson at his most ferocious. Franti’s music continues to evolve as well: the murky, Sly Stone-style funk of Spearhead’s second album, Chocolate Supa Highway, was richer than the down-home soul of their debut, and Stay Human branches out so wildly that there aren’t two similar songs on the disc. “Rock the Nation” tops a Zapp-like electro-funk rhythm with a flute hook that Dr. Dre would sell his last bag of chronic for, while “Thank You” is a disco homage that could’ve come straight out of the McFadden & Whitehead songbook. Furthermore, the six-foot-six Franti is riveting onstage–I saw him tell a story at a show a few years ago, and his voice alone kept a crowd of over a thousand rapt and silent for ten solid minutes. Saturday, June 23, 11 PM, Metro, 3730 N. Clark; 773-549-0203.