Joseph Ervin Duncan, better known as "J. Ebb," was born on February 18, 1909 in Douglasville, Georgia to John Raymond and Pearl (Perkins) Duncan. Duncan graduated from Douglas County High School in 1926 and then graduated from Young Harris College in 1928. He married Antoinette Talmadge Tyus on June 3, 1931 and they had three sons: Robert Tyus Duncan, Richard Allen Duncan, and Ebb Duncan Jr. Duncan Sr. passed away on January 19, 1980 due to a heart condition.

Duncan served in the Georgia House of Representatives from 1949 until 1964. He returned to the General Assembly in 1973 as a state senator where he was known as the most powerful senator in the state. Duncan served as Majority Whip, secretary of the Appropriations Committee, vice president of the Banking and Finance Committee, a member of the Human Resources Committee, as well as several other assignments. Duncan was also a member of numerous community organizations and served on the board of directors for several local businesses. He died while in office.

As a member of the Georgia Legislature, Duncan served under six governors. He was instrumental in bringing educational television to Georgia, making the University of West Georgia into a four-year institution, and supporting the creation of the university's modern campus. Duncan also worked to change Georgia State College into Georgia State University, and to purchase Jekyll Island for the state of Georgia. He helped Gov. Zell Miller and Rep. Nathan Dean get their start in politics.