Researchers from two London universities that teamed up with the Internet music site Last.fm have found hip-hop to be "the single most important event that has shaped the musical structure of the American charts" in the past 50 years—and presented factual evidence. 

According to the study published in the Royal Society Open Science journal on May 6, more than 17,000 songs that made up 86 percent of the U.S. Billboard Hot 100 between 1960 and 2010 were analyzed. Thirty-second clips taken from each song using music recognition technology were categorized by “topics relating to harmony and timbre,” then studied to see how the popularity around those topics fluctuated over five decades.

Armand Leroi, professor of evolutionary biology at Imperial College London shared the following with CNN. 

We had a sense that lots of people have opinions about popular music, but nobody has any objective evidence…. Everybody thinks the best music was produced when they were 17 years old. We wanted to do something better than that.

Read more on the study here.