#4 Social Signals Exist: December, 2010
Does Matt Cutts have a problem acknowledging obvious social signals? Sure he does! In December of 2010 Cutts acknowledged what everyone pretty much already knew; Google uses social signals to determine page rankings.
Cutts was quick to point out that merely having lots of followers wasn’t good enough to increase your page rankings, they had to be quality followers. In typical Google fashion, he wouldn’t really elaborate on what attributes made a follower a quality follower.