Girls' Generation includes a human.
Girls' Generation . The group is composed of eight members : Taeyeon , Sunny , Tiffany , Hyoyeon , Yuri , Sooyoung , Yoona , and Seohyun . Originally a nine-piece group ( with Jessica , who later departed from the group in September 2014 ) , Girls ' Generation debuted in 2007 with their Korean eponymous debut album . Kim Tae-yeon ( born March 9 , 1989 ) , referred to monomously as Taeyeon , is a South Korean singer .