Human Nature, the Australian act that celebrates Motown classics five nights a week at The Venetian, is experiencing a confluence of career milestones this year. The vocal quartet recently observed the second anniversary of the grand opening of The Motown Show at the Sands Showroom, and it’s been five years since Human Nature first stepped onto the stage as Vegas headliners at the Imperial Palace (now The Linq). Most importantly, bass singer Toby Allen, soul belter Phil Burton and smooth-as-silk singing brothers Andrew and Michael Tierney are celebrating 25 years since they first started harmonizing, with no plans to hang up their matching jackets any time soon.

The four friends’ combined entertainment experience shows when Human Nature, backed by the Funk Foundation and its keyboard-playing musical director Ronnie Foster, takes the stage and gets the audience on its feet. The hits from such Motown legends as The Temptations, The Four Tops, Stevie Wonder and Human Nature mentor Smokey Robinson come fast and furious, with the group switching off lead vocals without missing a synchronized dance step. But it’s their ability to effortlessly get even the most introverted people dancing and singing, let alone teaching them choreography to “Stop! In the Name of Love,” that speaks to the power of their brand of soul.

“We’ve noticed it since day one,” says Allen. “The thing that I really enjoy is seeing that crowd at the beginning of the show, and you look around and see some faces who might have been there before, and they know they’re going to love it so they’re already into it. But there are other faces that are like, ‘Come on, show me what you’ve got.’ A couple of songs in, you sort of see that change, and by the end of the show that same person will be up and dancing.”

While winning over audiences has been entirely satisfying for the singers, they have legions of fans back home who have been on board since they were boy-band heartthrobs in the ’90s. An April-May tour of Australia will find Human Nature celebrating its career catalog, including 2014 album Jukebox, which the group is working to get released in the U.S. (and considering promoting with a TV special). Meanwhile Allen, Burton and the Tierneys are looking ahead to see what kind of future is possible as Strip headliners.

“I think a lot of people leave the show just finding out about Human Nature, so we just kind of want to take that to the next level and show them more about us,” says Andrew Tierney, who sees the group having a long tenure in Las Vegas as long as the act can evolve. “We don’t want to do The Motown Show in 10 years time. I don’t think you’d see us doing that show, but hopefully you’ll still see Human Nature coming here. … It’s been amazing for us and we’ve been so embraced by Vegas that I think it’ll always be part of what we do, if Vegas is happy to have us.”

The Venetian, 7 p.m. Tues.-Sat., starting at $59.95 plus tax and fee. 702.414.9000