“Got to land on something and stick with it at some point,” said drummer Nathan Harwell.

Name-change refusal aside, Darwin would be proud; the band’s members constantly have adapted to suit each other’s strengths, and the act is an entirely new beast than when it began.

Guitarist Kyle Reid and vocalist Jon Barnoskie began playing as the acoustic duo Kyle and the Bear while attending school at the University of Oklahoma. Tapping Harwell as a drummer, they slowly added more pieces in bassist David Hickey, trumpeter Chris Schroeder and saxophonist Trevor Galvin, which have shifted dynamics drastically.

“Back then, we tried to fit what was already written,” Harwell said. “Now, all of us put in our influences and opinions. The songs sound like six pieces playing a song written by six people, as opposed to six pieces playing a song meant for two.”

With fewer inhibitions came an increased openness to opinions and new styles. Each member was nurtured with a distinct genre; the jazz influence rose to the top immediately, but others grew more prominent as time passed.

“We all had styles we gravitated toward as we learned our instruments. I’m not sure what genre you’d say, but you’ll definitely hear the blend of all of our influences,” Harwell said. “When I started playing, I tried to fit in with that jazzy vibe. I’ve kind of sucked it into another realm.”

Said Reid, “It used to be the jazzy songs with catchy melodies, all real light. Since then, there’s a new intensity and heaviness to the music. That’s a strong point. Even though it’s different styles, they work together and set us apart.”

The biggest tie between all the different shades is the band’s propensity for musical eras of yesterday.

“I’ve always been listening to old jazz records and blues albums,” Barnoskie said. “Older music just had this soul to it. You play that as an inspiration.”

Added Reid, “We are old-fashioned in the instrumentation. At the same time, there are new elements that, to a certain degree, accentuate the old stuff. You don’t know how beat-up your old tennis shoes are until you see someone’s new pair.”

Pairing the new with the old has worked well for the six-piece Fourtet, endearing itself to fans young and old, grabbing spots at Dfest and Norman Music Festival (not to mention Tuesday’s show at Coach’s Brewhouse). Possible dates await at Jazz in June and the Summer Breeze Concert Series in Norman. People keep showing up to dance, groove, admire and ponder what exactly it is they are listening to.

“I don’t think anyone has successfully pegged us,” Harwell said. “Not even us.”