In which I decide what I think about popular music
I started with the premise that music of this decade is completely nondescript; a person can almost immediately tell if a song is from the, say, 80s, but the only unique factor in what's considered popular by any standard today is exactly how NOT unique it is.

This was more or less based off what I see in trends in music in both building off and rejecting the ideas and ideals of the former decade. The 50s: songs that could be sung by your community barbershop quartet. The 60s: under-produced proto-rock and the fusion of psychedelia into the mainstream. The 70s: acoustic folk sung by long-haired pussies, arena rock, and disco. The 80s: new wave, R&B, and glam. The 90s: grunge, hip-hop/rap, and the various outcroppings of alt-rock. The 00s: ?

Certainly, the end of the last decade saw the fusion of rock and rap, the fusion of R&B and hip-hop, and the fusion of underground xxx with more mainstream yyy. (To wit: I love hardcore punk AND I love Slayer. Metalcore was the late-90s, early-00s answer to the question of where my entertainment dollar should go.)

But, I conjectured it was this late-90s fusion-mania that has caused this problem. If so, we should see music before this have distinct genres (and not after). Obviously, we'd allow for the occasional novelty song or infectious groove to gain exposure (ala In Da Club, which was a bit of both).

To test it, I started looking at a random sampling of Billboard number-one hits by year. To be truly scientific, I'd have to select a constrained set (those songs that were number one on February, May, August, and November 1st, for example), but since this is a blog and not a formal thesis, I tried to fairly cherry-pick some examples by-year.

2008
Disturbia (Rihanna)
I Kissed A Girl (Katy Perry)
Touch My Body (Mariah Carey)
Low (Flo Rida/T-Pain)

2007
No One (Alicia Keys)
Crank That Soulja Boy (Soulja Boy Tell 'Em)
Hey There Delilah (Plain White T's)
Makes Me Wonder (Maroon 5)
Irreplaceable (Beyonce)

2006
SexyBack (Justin Timberlake)
Promiscuous (Nelly Furtado/Timbaland)
Bad Day (Daniel Powter)
Grillz (Nelly/...)

2005
Gold Digger (Kanye West/Jaimie Foxx)
We Belong Together (Mariah Carey)
Hollaback Girl (Gwen Stefani)
Candy Shop (50 Cent/Olivia)
Let Me Love You (Mario)

2004
My Boo (Usher/Alicia Keys)
Lean Back (The Terror Squad)
I Believe (Fantasia)
Yeah! (Usher/Lil John/Ludacris)
Hey Ya! (Outkast)

2003
Baby Boy (Beyonce/Sean Paul)
Shake Ya Tailfeather (Nelly, P. Diddy/Murphy Lee)
Crazy In Love (Beyonce/Jay-Z)
Get Busy (Sean Paul)
In Da Club (50 Cent)
Lose Yourself (Eminem)

2002
Dilemma (Nelly/Kelly Rowland)
A Moment Like This (Kelly Clarkson)
Foolish (Ashanti)
Ain't It Funny (Jennifer Lopez/Ja Rule)
How You Remind Me (Nickleback)

2001
Family Affair (Mary J. Blige)
I'm Real (Jennifer Lopez/Ja Rule)
Lady Marmalade (Christina Aguilera/Lil' Kim/Mya/Pink)
Butterfly (Crazy Town)
Independent Women Part I (Destiny's Child)

2000
With Arms Wide Open (Creed)
Music (Madonna)
Incomplete (Sisqo)
It's Gonna Be Me ('N Sync)
Everything You Want (Vertical Horizon)
I Knew I Loved You (Savage Garden)
Smooth (Santana/Rob Thomas)

1999
Unpretty (TLC)
Bailamos (Enrique Iglesias)
Genie In A Bottle (Christina Aguilera)
If You Had My Love (Jennifer Lopez)
Livin' La Vida Loca (Ricky Martin)
Believe (Cher)
...Baby One More Time (Britney Spears)

1998
I'm Your Angel (R. Kelly/Celine Dion)
The First Night (Monica)
One Week (Barenaked Ladies)
The Boy Is Mine (Brady/Monica)
Gettin' Jiggy Wit It (Will Smith)
Truly Madly Deeply (Savage Garden)

1997
Candle In The Wind 97 (Elton John)
Mo Money Mo Problems (The Notorious B.I.G./Puff Daddy/Mace)
MMMBop (Hanson)
Wannabe (Spice Girls)
Un-Break My Heart (Toni Braxton)

1996
No Diggity (Blackstreet/Dr. Dre)
Macarena (Los Del Rio)
Because You Loved Me (Celine Dion)
One Sweet Day (Mariah Carey/Boyz II Men)

1995
Fantasy (Mariah Carey)
Gangsta's Paradise (Coolio)
Kiss From A Rose (Seal)
Waterfalls (TLC)
This Is How We Do It (Montell Jordan)

1994
I'll Make Love To You (Boyz II Men)
Stay (Lisa Loeb)
I Swear (All-4-One)
The Sign (Ace of Base)
Hero (Mariah Carey)

1993
Again (Janet Jackson)
I'd Do Anything For Love (Meat Loaf)
That's The Way Love Goes (Janet Jackson)
Informer (Snow)
I Will Always Love You (Whitney Houston)

1992
End Of The Road (Boyz II Men)
Baby Got Back (Sir Mix-A-Lot)
Jump (Kris Kross)
Save The Best For Last (Vanessa Williams)
All 4 Love (Color Me Badd)
Black Or White (Michael Jackson)

1991
When A Man Loves A Woman (Michael Bolton)
Emotions (Mariah Carey)
Good Vibrations (Marky Mark and the Funky Bunch)
The Promise Of A New Day (Paula Abdul)
Unbelievable (EMF)
Baby Baby (Amy Grant)
Gonna Make You Sweat (C+C Music Factory/Freedom Williams)
Justify My Love (Madonna)

1990
I'm Your Baby Tonight (Whitney Houston)
Black Cat (Janet Jackson)
Close To You (Maxi Priest)
Step By Step (New Kids On The Block)
Hold On (Wilson Phillips)
Nothing Compares 2 U (Sinead O'Connor)
Another Day In Paradise (Phil Collins)

...it became apparent to me that popular music sounded like this for years, WAY before my theory about how the fusion of different genres has washed-out music. I doubt Wilson Phillips, for example, could become popular today, but is it inconceivable a young Janet Jackson was yesterday's Rihanna? That pop music never changed so Rihanna isn't retro in any way?

(As you start going back through the 80s, number one hits start diversifying. But trust me -- if Lionel Richie were young today, he'd be doing his third hit as a collaboration with Flo Rida if he could.)

In other words, what is popular today -- R&B alternating between having a hip-hop/rap edge, R&B with a dance edge, and straight-up sappy R&B -- could have been number one in 1990, and no one would have stopped to say how progressive it was.

For what it's worth, looking at the modern rock hits since 1990 shows similar lack of growth. The Offspring, Staind, the Foo Fighters, and Weezer have all topped that chart this year. In general, though, this decade has seen a lot of pop- (which includes The Offspring) and emo-punk bands get heavy rock play. So, at least if you heard a rock song of that ilk, you could peg the decade.

So: my theory is wrong for popular music because it's been dominated by R&B since at least the mid-80s. My theory may be closer for rock, though a similar exercise as above proves difficult to put songs into any specific bucket like new wave, grunge, or nu-metal anymore.