Oh, how time flies.

It’s been 10-plus years since the three blonde, shaggy-haired brothers known as Hanson left their first musical mark on the world.

All grown up · (left to right) Zachary, Taylor and Isaac Hanson play Club Nokia with HelloGoodbye Saturday. - Photo courtesy of Ken Phillips Publicity

“Mmmbop” helped solidify Hanson’s place in the hearts of diehard fans who have stayed resilient over the group’s decade-long career.

Back then the trio’s music, laced in perfect harmonies and ridiculous falsettos, helped define an interesting tween music culture characterized by all-things bubblegum and Total Request Live. Apart from the cheesy choreography and clean-cut hairdos, Isaac, Taylor and Zac Hanson always ran astray from pop music’s mainstream formula. A formula of its own, Hanson was the unique complement — part indie, part folksy, part rock and part pop.

But a lot has changed since then. For one, all the band members are now husbands and fathers, which makes the prospect of touring difficult.

“It’s definitely hard, especially when kids get old enough to understand and tell you they miss you. You feel like ‘old dad’ each time you get on the tour bus,” said Taylor Hanson, the group’s lead vocalist.

For the brothers, the pathway to musical success hasn’t always been easy. Even with respectable sales of the band’s debut album, Hanson fell victim to diffused record labels and later, in-fighting with executives over creative control. While other groups took off, Hanson’s music stalled.

But Isaac, Taylor and Zachary never completely left the scene. With four studio albums and three Grammy nominations already under its belt, Hanson is busy at work on its fifth CD, due out spring 2010. Currently, the Tulsa, Okla. natives are traveling the country opposite rock band HelloGoodbye on the Use Your Sole Tour presented by Toms Shoes. The trio will play in Los Angeles on Saturday.

The brothers’ presence on the tour speaks to Hanson’s fight to stay culturally viable. As veteran rock stars living in a society faced with huge global concerns, a band trip to Africa in the summer of 2007 became a real eye-opener for the brothers.

“We spent some time in Africa not on tour, but just going as guys,” Taylor said. “We saw people who didn’t even have basic needs like shoes or water, and we felt like we should do something about it.”

The band has worked with the shoe company Toms Shoes ever since to help donate thousands of shoes to children in need. They launched the Take The Walk campaign, a series of organized one-mile walk events held before each concert in cities around the world.

Since the start of 2008, together they have completed more than 24,902 miles, a full lap around the globe.

“The charity work that Toms Shoes does is something, as a group, we strongly believe in,” Taylor said. “It really makes you recognize how simple needs can make a big difference and how our generation can be empowered to make change.”

In line with the cause, Hanson will also be debuting a new EP on tour called Stand Up Stand Up, a collection of acoustic versions of songs on its upcoming full-length album. In addition, the EP will include one studio cut, “World’s on Fire,” a politically conscious spitfire of a track that is not only beautifully written but also incredibly well executed. Breathy, impassioned vocals inquire, Do they know the world’s on fire? — meaningful lyrics all to the backing of a light thumping on the drums.

Musically speaking, don’t expect any half-hearted generalities — Hanson’s heart is in it.

“It’s our call to action anthem, and we’re proud of it. It’s a powerful thing to be able to connect a song with a message,” Taylor said. “Everyone faces the challenge of whether to get involved or not. We’re not preaching, just posing the question.”

Adding activism to their résumés, the Hanson brothers have still found time to unwind, let loose and regain focus on the music.

“Being on the road is exciting,” Taylor said. “It gets us pumped to be able to share new music each night with our fans.”

Hanson’s new material justifies the band’s lasting appeal. More than 12 years after “Mmmbop” graced radio airwaves, a dedication to charity and attention to social issues puts Hanson at the forefront of musical and cultural relevance.