The Roots

After paying dues with two fine albums of homemade rap-jazz jams, the Roots took hold with 1996's gritty Illadelphia Halflife and that album's subsequent tour. With the success of 1999's Things Fall Apart (which featured the mesmerizing "You Got Me" with Erykah Badu), the crew found itself representing not just Philly but a new wave of "conscious" rappers that also included Mos Def, Talib Kweli, and Common. A mix of live instrumentation and positive lyrics proved to be the Roots' sorcerer's stone, luring in enough white and female listeners to anoint the band the "anti-bling bling."

The waning role of MC Malik B, whose street narratives once served as a vital counterpoint to Black Thought's safer, wisdom-rich wordplay, made this audience shift possible. Don't think the Roots liked Malik's lack of participation, however: "Water," the most important song on Phrenology and probably of the band's career, shows why the MC isn't more present, probing B's drug addiction. After narrating the pair's history, Black Thought urges his friend to "Walk straight and master your high/ Son, you're missing out on what's passing you by," and asks those with a comrade in a similar situation to "Give a pen to him/ Or lock him in a studio with a mike/ 'Cause on the real it might save his life."

Elsewhere, the album feels more formulaic, mostly divided between romance jams and party joints. On the slow tip, "Complexity" gives "You Got Me" a classy run for its money, while "Break You Off" crassly chases the green with a cheesy R&B chorus by Musiq. Showcasing producer ?uestlove's versatility, the better uptempo shots include "Rolling With Heat," featuring MC Kweli over a hard drum break and synthesizer bass line, and the catchy, altrock-meets-neo-soul number "The Seed."

However, a lack of synergy plagues half a dozen other tracks, with run-of-the-mill verbiage failing to capitalize on sizzling beats, or vice versa. Tempos often feel rushed (probably the better to play live), and Thought's lyrics, while clever, are often trivial, finding a thousand ways to say, "Throw your hands in the air." Never has it been clearer how Malik B kept the outfit's identity raw.

Ultimately, since the Roots helped catalyze a major listener change in rap, the story of Phrenologymight be in how it's received. Has the crew diverged from its roots so much that there'll be a conscious-rap backlash? Or will thug-rap addicts and Lollapalosers alike drink in the message of "Water"? As the title -- which refers to the science of correlating skull shapes to personality traits -- implies, this album's most important function may be to measure the mind-set of hip hop heads today.