How many times have I heard this: “Hip-hop lost its way when we started nodding heads instead of shaking butts”? Usually the expression refers to the profoundly unfunky, nonrhyming, pseudo-metaphysical babble of artists like Ras Kass and Company Flow who flourish in the mystifying world of underground hip-hop.

Maybe people are nostalgic for the Golden Age, when hip-hop meant a devotion to the art of moving butts. On the other hand, the vacuous, flimsy pop rap on current mainstream radio makes a pretty poor case for the value of danceable music.

Thankfully, Los Angeles hip-hop fundamentalists Dilated Peoples give us both qualities — as long as your version of dancing involves a fractured spine, loose bowels and punctured eardrums. Expansion Team, the group’s second album for Capitol Records, bumps like no record in the last three years (with the possible exception of their previous LP).

All 16 tracks display near-perfect musical sensibility, and they’re effective because the overall rhythmic aesthetic is one of layering and stratification. Producers, including Evidence, Babu and Alchemist (plus guests), stab and loop precisely chosen samples over neck-snapping beats.

On the bottom, we have heavy kicks and chopped bass lines, and above that, crackling snares and sparse hi-hat figures. Imported melodic fragments swirl and crash into place, and resident turntablist DJ Babu cuts through the texture with complex scratch patterns of astonishing rhythmic acuity (even compared with his pioneering work in the Beat Junkies). Over it all, Dilated emcee Rakaa-Iriscience lays his rough, gospel-nuanced flow alongside the searing drawl of his partner Evidence.

And that’s just the music. Rakaa and Evidence consciously frame their words as the foundation of a cross-cultural urban movement. From Rakaa: “I embrace the tasks that give birth to tools/ And keep the pressure on that turns earth to jewels.” Throughout their career, they have asserted that hip-hop can pave the way for cultural and social solidarity.

The very composition of the group demonstrates this belief. Dilated Peoples represents both the artistic diversity of hip-hop and the racial diversity of urban America. Rakaa is an black emcee, Evidence is a white graffiti artist, and Babu is an Asian turntable wizard — all they need is a Puerto Rican b-boy and they’d have New York hip-hop right there.

Of course, Dilated Peoples isn’t all high-minded message, and they’re not above more commonplace hip-hop braggadocio (albeit much more literate and forceful). Songs like “Clockwork” and “Hard Hitters” show that hip-hop’s roots in competitive wordplay still inform the music 30 years later.

There is, however, a resultant limiting of subject matter, and for those who love songs about everything in life, this will prove a major drawback. Hip-hop can indeed take on diverse issues in compelling ways, and in truth it’s disappointing to find that Expansion Team makes little effort to do that.

On the other hand, when “diverse content” means a ridiculously comical glorification of misogyny and violence (see: most mainstream commercial rap), it’s a relief to get back to hip-hop’s fundamentals. In other words, if it’s a choice between meaningless rump-shaking and a head-nodding celebration of hip-hop itself, I’ll take the latter any day.