What constitutes a boy band, anyway? One Direction certainly look and act the part. Ever since forming on The X Factor in 2010, they’ve filled a particular hole in the music industry, the one that requires 3-5 fresh-faced young lads with pretty voices and prettier haircuts to join forces and passionately emote for the hormonal stimulation of preteens. Yet over the course of four albums in four years, the British quintet has served as a reminder that the phrase “boy band” is almost as elastic as the concept of pop itself. Four, the aptly titled LP One Direction released this week, contains music of a different sort than we’ve come to associate with the Tiger Beat archetype.

For a good solid 15 years, torchbearers New Kids On The Block, the Backstreet Boys, and *NSYNC taught us that dance-pop — and (especially) dance routines! — were essential boy-band components. 1D don’t really do that. The original boy band, the Beatles, slung teeny-bopping pop songs from behind guitars, as did One Direction’s immediate forebears, the Jonas Brothers, and 1D’s protégés turned peers 5 Seconds Of Summer. Harry, Zayn, Liam, Louis, and Niall don’t really fit that mold either. And although you’d think a boy band that doesn’t dance nor play its own instruments is at a distinct disadvantage, the lack of distinguishing factors has allowed One Direction to be a lot of different things at once.

From breakout single “What Makes You Beautiful” forward, guitars and gang choruses have loomed heavily in One Direction’s sound. That song and last year’s smash “Best Song Ever” both could pass for Hot Chelle Rae, the leather-jacket-clad pinups who scored a handful of hits like “Tonight Tonight” (that inescapable Zac Galifianakis tattoo song) without making much of a cultural dent. But if 1D’s first and biggest hits were bright, punchy pop-rock tunes, last year’s Midnight Memories found them slowly venturing out into other guitar-based genres, with those massive choral choruses often serving as the only aesthetic glue. Their SNL performance of “Story Of My Life” was straight-up Mumford lite. (They’ll be back at 30 Rock next month, BTW.) Title track “Midnight Memories” was so hair metal I’m almost surprised its video didn’t feature a supermodel writhing on top of a car. As Grantland’s Steven Hyden pointed out, the power-pop number “Little Black Dress” could pass for Big Star.

Four is a little more consistent genre-wise, or at least era-wise — which is to say it sounds a lot more like ’80s pop than Taylor Swift’s 1989 does. The resemblance between lead single “Steal My Girl” and Journey’s “Faithfully” has been widely noted, and much of the album continues in that earnest arena-rock mode; consider it the blooming of the seeds that were planted when The Sopranos helped a new generation reclaimed “Don’t Stop Believing” as an ultimate karaoke jam. Many of the ballads bear distinct traces of tame hair metal descendants like Mr. Big’s “To Be With You” or Extreme’s “More Than Words.” The soaring “Where Do Broken Hearts Go” might make you rethink Bon Jovi’s entire discography. And although I’m disappointed to report that “Stockholm Syndrome” is not a Yo La Tengo cover (and maybe even more bummed that it’s not their defanged take on Muse), I can report that 1D’s “Stockholm Syndrome” is first-rate synth-pop with a kick.

Some of the Midnight Memories touchpoints remain: “Ready To Run” further explores the Mumford & Sons thing, but with an easygoing glide in place of Marcus Mumford’s clenched-sphincter intensity. “No Control” offers more power-pop riffage worthy of Cheap Trick. Elsewhere Four manages to work in new flavors that help to further disintegrate the boundaries between indie rock and mainstream pop. I’ve already noted how much the blithely baroque “Fireproof” reminds me of latter-day Belle And Sebastian’s pleasant singsong, but that Dear Catastrophe Waitress sound now feels as ancient as any of the other retro styles 1D revisits here. Four feels strikingly current when it taps into the electrified, hook-laden, genre-defying sound today’s alt-rock radio programmers crave. “Girl Almighty,” “Spaces,” and especially closer “Clouds” are impossible to differentiate from whatever passes for indie rock these days.

I’ve written at length about the gradual disintegration of genre boundaries, asserting that the most adaptable musicians — the ones who manage to incorporate a little of everything without compromising their essence — are the ones most likely to survive. By refusing to slide neatly into a genre while still developing a signature sound, 1D have positioned themselves to be that kind of act. On top of that, unlike most boy bands, they probably won’t have to split up into solo careers to have a shot at aging gracefully. Four is an album of sleek, shiny pop music shallow enough for a middle-schooler to comprehend, yet there’s no reason One Direction should have to wink their way through these songs 20 years from now. It’s not exactly Sgt. Pepper, but it’s smart evolution all the same.

CHART WATCH

The biggest chart news of the week is not the placements themselves but the revelation that Billboard will soon factor streaming and track sales into the Billboard 200 album chart. The methodology seems clumsy to say the least — I’m not sure 10 individual track downloads equates to one album sale — but the need for some kind of evolution is obvious. On first pass, it seems like the changes will result in the singles chart and the albums chart moving a lot closer to each other. We already noted that young pop stars such as Ariana Grande will benefit while the old-timers who’ve charted well this year (Barbra Streisand, Tony Bennett) will suffer. What remains to be seen is how this will affect bands like Arcade Fire and Vampire Weekend, who’ve managed #1 albums under the current system; would an artist like Spoon, whose They Want My Soul debuted at #4 this summer, have any chance at a top 10 debut under this new system? I can’t see how they would stand a chance considering the number of people streaming radio hits online every day, but Daniel Glass of Glassnote Records (Chvrches, Mumford & Sons, Childish Gambino, Phoenix) seems to think it will be a positive thing for his artists. So who knows! I’d like to see a statistical analysis of how various 2014 releases would have fared under the new rules.

The updated system goes into effect 12/4 and will be reflected in the 12/13 charts. Until then, the albums chart will be based on sales only, and those sales once again spoke loud and clear in favor of Taylor Swift this week. 1989 is #1 for a third straight week, moving 312,000 copies to handily defeat strong debuts by three surefire legacy acts: Foo Fighters’ Sonic Highways (#2, 190,000), Pink Floyd’s The Endless River (#3, 170,000), and Garth Brooks’ Man Against Machine (#4, 130,000). Any of those would have easily started at #1 on an average week, but the heavy hitters are all coming out for a big Q4 push. Billboard notes that Swift’s album has now topped 2 million copies, and her discography’s collective 27 weeks on top ranks her third all-time among female artists after Whitney Houston (46) and Mariah Carey (30). Her third-week sales tower over almost every other album’s first-week sales. It would take a lot, but with the right holiday push 1989 could actually surpass the Frozen soundtrack’s 3.5 million to become the year’s best-selling album. More on Swift in a second.

Up against all those six-figure debuts, Big K.R.I.T.’s 44,000 for #5-debuting Cadillactica seems puny, but it’s a strong accomplishment for a great rapper who gets basically zero radio support. On the other hand, I continue to be surprised that Nick Jonas’ self-titled effort didn’t sell better; just over 37,000 and a #6 debut seems low for a strong album from an actual famous person. Now 52 is down to #7 this week with 37,000, while Pentatonix’s That’s Christmas To Me rises significantly from #23 to #8 with 34,000 no doubt thanks to the holidays approaching. Sam Smith’s In The Lonely Hour is at #9 after logging just over 30,000 in sales (nothing to sniff at for a record that came out five months ago!), while George Strait’s The Cowboy Rides Away rockets from #60 to #10 with 30,000 thanks to a Walmart-exclusive deluxe edition.

Over on the Hot 100 singles chart, Swift set another record, becoming the first woman to succeed herself at #1 as “Blank Space” unseats her own “Shake It Off.” Billboard notes that nine previous acts have accomplished the feat, though prior to 1994 only the Beatles had done it, landing three consecutive #1s in 1964 with “I Want to Hold Your Hand,” “She Loves You,” and “Can’t Buy Me Love.” Since then Boyz II Men, Puff Daddy, Ja Rule, Nelly, OutKast, Usher, T.I., and the Black Eyed Peas have pulled it off. “Blank Space” becomes Swift’s third #1 single after “Shake It Off” and “We Are Never Getting Back Together.” It climbs from #13 last week, the largest leap to #1 since Miley Cyrus went from #22 to #1 with “Wrecking Ball” last September, and like “Wrecking Ball,” “Blank Space” benefitted from a smash viral video. 1989 is the first album since Macklemore & Ryan Lewis’ The Heist to see its first two singles go to #1 last year, and it’s the first album by a woman to do so since Adele’s 21 in 2011-2012. Also, Swift now the only artist with two #1 singles in 2014 — much to Radio Artist Of The Year and noted Swift nemesis Katy Perry’s chagrin, I’m sure.

The one thing Swift didn’t manage to do is go 1-2. Meghan Trainor’s “All About That Bass” holds at #2, while “Shake It Off” falls to #3. Maroon 5’s “Animals” is at #4, followed by Tove Lo’s “Habits (Stay High)” at #5. Hozier’s “Take Me To Church” rises to a new peak at #6, meaning Bobby Shmurda’s “Hot Boy” falls to #7 after peaking at #6 last week. Jessie J’s Ariana Grande- and Nicki Minaj-assisted “Bang Bang” slides to #8. Smith’s “I’m Not The Only One” rises to #9, Smith’s third top 10 single this year and second as a lead artist. Closing out the top 10 is Jonas’ “Jealous,” jumping from #23 to #10 no doubt in part due to people streaming Jonas’ new album.

TRACK CITY

Catey Shaw – “Night Go Slow” (Week In Pop Premiere)
After putting her name on the map with the polarizing “Brooklyn Girls,” Catey Shaw returned with the entertaining and catchy “Human Contact” and the smoky midtempo jam “Outerspace.” Now here’s another look from the pop singer, a tasteful ballad called “Night Go Slow” that lets its emotions simmer without ever boiling over. It’s accompanied by a video depicting ladies in love on the run. Watch below.

Little Brutes – “Carefully” (Week In Pop Premiere)
L.A. duo Little Brutes have an EP called Desire coming in January, and if all the songs are on par with “Carefully,” it’s going to kill. This song boasts sleek, understated ’80s-inspired production and one of the best hooks of the year. It reminds me of a more crystalline Jessie Ware, which is a serious endorsement coming from me. I heartily advise you to listen.

Hozier – “From Eden”
My feelings about Hozier remain incredibly beige.

Wyclef Jean – “Divine Sorrow” (Feat. Avicii)
Wycelf hasn’t released any exciting music since The Ecleftic, which came out almost 15 years ago, and this song certainly doesn’t change that. His philanthropic efforts haven’t gone so hot either. But yeah, hard to hate on the guy when he’s fighting AIDS (assuming the profits from this aren’t secretly funding the construction of Jean’s beachfront mansion or something). Gonna assume RED’s involvement means this is legit.

Avicii – “The Nights”
Double the Avicii this week! And unlike the above Wyclef collaboration, there’s no charitable component to this, just funding Avicii’s unquenchable creative thirst. Alas, now that the novelty of the “folk + EDM = hit” equation has worn off, this pretty much sounds like trash.

K. Michelle – “How Do You Know?”
Hot damn, this K. Michelle album is shaping up nicely. She sings, “It feels so good in the moment, but it’s just a moment/ That’ll soon be over, once my thoughts are sober.” she sings. Yet “How Do You Know?” sounds better with each passing day.

Meghan Trainor – “I’ll Be Home”
All I want for Christmas is for Trainor’s 15 minutes to be over.

NEWS IN BRIEF

• Solange’s wedding looks like it was a lot of fun; she and her son danced to “No Flex Zone.” [Jezebel]
  
• Talent scout Wendy Starland won a $7.3 million lawsuit after the court found that she deserves credit for helping to discover Lady Gaga. [Billboard]
  
• Justin Timberlake became part-owner of AfterMaster, a company geared toward improving songs’ sound quality. [Entrepreneur]
  
• Sia, Katy Perry, Selena Gomez and others have contributed to a Kickstarter for “the first documentary about golf and spirituality… ever!” [Idolator]
  
• Rihanna’s album is “coming very soon,” whatever that means. [Popjustice]
  

HOLD ON, WE’RE GOING HOME