Change is the natural order as avant-garde jazz-fusion trio Medeski, Martin and Wood (MMW) returns to Northampton. The famed instrumental trio made up of John Medeski (keyboards), Billy Martin (drums) and Chris Wood (bass) is coming back to the Pioneer Valley for the first time since their successful run of shows with non-conformist jazz-guitar phenom John Scofield. Dubbing their new tour “viva la evolution,” the trio is bringing an unconventional approach along with an onslaught of unreleased material to the Calvin Theatre Friday, Feb. 29. The improv-based group from New York City has come a long way since it started touring in a beat up RV in 1993. They’ve played alongside jam bands like moe., Phish and countless others, yet they continue to defy a specific label. “People with pop and rock backgrounds consider us jazz, but people into jazz consider us rock,” said Medeski, a New England Conservatory grad. “I just try to play like me.” No matter what style you may consider MMW, the band does not cease to evolve. Following their January Little Monsters Records release of “Let’s Go Everywhere,” MMW’s first album for kids, they are touring again as the trio, but their philosophy and outlook toward music is in yet another process of metamorphosis.

Instead of touring post-record release, the band took five days to specifically craft new material for the “viva la evolution” tour. The 10-stop tour will take MMW from New Jersey to Vermont, ending in Northampton. The shows will be used by the band to polish its new arsenal of tunes fresher than the Berkshire DC.

Of the new writing and recording process, Medeski said, “We just wrote the basic sketches for the songs and plan to record in a very live style.” The band will head into the studio to record the progress of the tour after the Calvin Theatre show. Medeski, the piano man in charge of all things melodic, said the band is like a canary; a bird who sings one song for a year and changes year after year. The band is adopting this natural process of change and it plans to release three albums in 2008 using this reverse style.

The band draws its influence from all sounds, sights and senses. Medeski said he owes much of his inspiration to impulse and the nature of the world changing around him. From the rhythm of the subway, to the sound of birds, to the colors of a falling sun, nothing is above inspiration. This is the foundation for their tour; they write the music and allow their performances to nurture the tones, as they are inspired by everything from the fans, to the venue, to the seasons. Because of this, the songs from “viva la evolution” will be retired after the tour to make room for new creations on the road.

With the current tour, the trio will pay homage to their developing music. Its very origin means “long live the evolution,” and it is a battle cry for change.

The band’s impromptu jamming makes every live experience with MMW fresh. Medeski describes the trio’s philosophy for writing as “leaving a lot of room for improvisation; set up the structure with specific elements that can be morphed into different music every night.”

Knowing the dynamics of the band, by the time they reach Northampton the music will be completely crafted and open to some very experimental improvisation.

The problem: the band could come out with a real dirty, funky sound rooted in hip-hop trance beats, or they could come out with a more psychedelic frame of mind. This often leads to a more experimental MMW that can become very mundane if you’re not expecting it. But one thing is true of the band, when it’s on, it’s on.

This show will give fans the chance to see the band create the sounds that will appear on the new album, whose name will evolve, said Medeski. And with this being the last stop of their tour, they will have to step up their game.

Tickets are going for $25 and you can find out more about the 8 p.m. Feb. 29 show at www.iheg.com.

Hunter Amabile can be reached at [email protected].