Robin Thicke 'Blurred Lines' and the 21st Century Success of the Genre-Bending Song [VIDEOS]

There's no doubt that "Blurred Lines" is the summer song of 2013. According to Billboard, the song has sold over 2 million downloads. It also has the No. 1 spot on the Radio Songs chart and a music video with over 86 million views. Though the scandalous music video helped propel "Blurred Lines" into a hit, it's really the song's blend of different music types and impeccable writing that has made it appeal to a wide audience.

"Blurred Lines" appeals to fans of all different music genres. The song blends together funk, pop, hip-hop, R&B and even a little old school rock to make what seems to be the perfect song.

However, Robin Thicke's hit song isn't the first track to blend several genres and be beloved by music fans and critics alike. Several of the biggest songs from the last 13 years have used the specific blend of R&B, pop and rock in order to skyrocket to the top of the charts.

The most notable song, and one of the first to do so in the 21st century was Outkast's "Hey Ya." One of the biggest songs of the 2000s, "Hey Ya," written by Andre 3000 and released in fall 2003, mixes together everything but the kitchen sink, musically. Light acoustic guitar strumming, funky electronic backbeats, the up-tempo danceable melody and Andre 3000's out-of-control vocals make for a chaotic song that shouldn't work but does.

Because of its odd composition and mixture of funk, rock, R&B, hip-hop and pop, "Hey Ya" crossed over from the hip-hop charts to the Top 40. It topped the Billboard Hot 100 chart in 2003 for nine weeks and gave OutKast one of the most successful and well-remembered songs of the decade.

The impact of "Hey Ya" on music writers seems to have been noted and replicated. Throughout the 2000s, the top-charting songs all seem to have blended together R&B, pop and rock.

Usher's "Yeah" (2004), Black Eyed Peas "I Gotta Feeling" (2009) and Kanye West's "Gold Digger" (2005) are all based in hip-hop aesthetics but take their music to the next level by having a higher, more complex production value. The songs are all incredibly loud and busy, much like "Hey Ya," and gave rise to this musical trend.

The hit that transitioned the R&B/pop/rock blend into the next decade was Cee-Lo Green's "F**k You." Despite it's obscene title and biting lyrics, "F**k You" peaked at No. 2 on the Billboard Hot 100 in 2011 (held off by Lady Gaga's "Born This Way") and hit No. 1 on the Pop Songs chart.

More so, it was loved by fans and critics alike, eventually winning the Grammy for Best Urban/Alternative Performance in 2011 and being nominated for Record and Song of the Year.

And it was so successful not just because it was critically adored, but because it mixed together Motown funk rock sensibilities with biting R&B lyrics and a sunny pop melody.

This formula is now seen in "Blurred Lines," proving that as much as music changes, it stays the same. Featuring the uber-successful Pharrell and rapper T.I., "Blurred Lines" once again has shown that if you want a mega-hit in the new century, you can't just stick to one genre.