Squire: Mixing and mashing genres

Music is an ever-changing mechanism. A song is in this week and out the next. An artist is in… Music is an ever-changing mechanism. A song is in this week and out the next. An artist is in this album and out the next. It’s ever-evolving and unpredictable, especially in the genre-crossing surge of the last decade.

Of course, this dates back to the Run-D.M.C. and Aerosmith collaboration, when they confidently plowed through the proverbial wall between rock and rap with “Walk This Way.”

In a lot of ways, many of the collaborations since have been matches made in musical heaven — think Jay-Z and Linkin Park, even though I would have been happier if they wrote and recorded new songs for Collision Course instead of lazily stringing pieces of their previous hits together.

Then we have our disasters — think Lil Wayne and mostly anyone else who’s not a rapper or in his Young Money crew. I think we can safely say that his addition to Jason Mraz’s “I’m Yours” was cringe-worthy.

Finally, there are the collaborations we expect, from Lady Gaga and Beyonce — the annoying and overplayed “Telephone” — to Jay-Z and Alicia Keys — the fantastic but overplayed “Empire State of Mind.”

Many of these artists joining forces have previous ties to one another that foreshadow a collaboration.

Every now and then, though, we’re sidetracked with a compelling and unforeseen collaboration, like “Airplanes,” a bombastic, passionate and reflective track featuring B.O.B., Hayley Williams — from Paramore — and Eminem.

Each verse is addictive and nearly terrifying in the way it addresses the daunting question of “What If?” in between Williams’ haunting chorus: “Can we pretend that airplanes in the night sky [are] like shooting stars / I could really use a wish right now.”

As Eminem ponders, “Let’s pretend Marshall Mathers never picked up a pen,” my heart drops just thinking about how radically different — and horrifying — pop culture and music would be had he never traumatized us with hit after hit.

Williams definitely has the power to carry this track — her vocals are stunningly interwoven between B.O.B.’s angry reflection and Eminem’s frantic pleas to his adolescent self.

That being said, it’s great to hear obnoxious, ultimately awesome rap anthems featuring every popular rapper on the planet (“Swagga Like Us,” “Forever,” “U Ain’t Neva Gotta Ask”).

But you have to admit that it’s just as awesome to hear Snoop Dogg backing Katy Perry while she sings about daisy dukes and “bikinis on top” (“California Gurls”).

Also, with the confirmation that T.I. and Lady Gaga recorded a track together for his upcoming album, the trend of inter-genre couplings has no intention of slowing down. I can’t say I’m disappointed.