I'm not the only one who has made these suggestions.

George Pullen Jackson (1874-1953) was an American educator and musicologist.
Jackson was a native of Monson, Maine. He was a pioneer in the field of Southern (U.S.) hymnody. Many consider him the "most diligent scholar of fasola singing" in the 20th century and one of the foremost musicologists of American folk songs. He was responsible for popularizing the term "white spirituals" to describe the "fasola" singing.
During the 1940s, Jackson studied the roots of anabaptist music (Amish and Mennonite). He proposed the now generally accepted view that the original tunes used in Der Ausbund hymnal were popular medieval melodies.[1]Der Ausbund is still used by Amish groups and has the distinction of being the hymnal with a history of the longest continual use (1564 to the present; the latest edition being published in 1999).[2]

If you can get hold of his article on Stephen Foster in The Musical Quarterly Vol 22, Jan Oct 1936, you'll find it quite enlightening.