These Dancers With Down Syndrome Will Make You 'Happy'

Watching people dance to almost any song is usually a happy experience. Watching those living with Down syndrome dance to the snappy beats of Pharrell's soon-to-be-played-out "Happy" is something approaching joy.

Since 2012, the world has been celebrating World Down Syndrome Day on March 21st. This 21st day in the third month of the year was chosen, according to the U.K.-based Down Syndrome International, because it helps highlight the triplication (trisomy) — also known as the "extra chromosome" — of the 21st chromosome, which causes Down syndrome.