Jazz musician and Yale music scholar Willie Ruff, who uncovered the links between 18th century Scottish singing and black gospel music, has connected another group to the style: American Indians.


A descendant of an Oklahoma tribe contacted him after learning about a 2005 Yale conference on line singing, an a cappella vocal form that originated in Scotland and is still sung in parts of the South. And this month, a second conference at Yale featured Muskogee Creeks singing with Baptist groups from Alabama and Kentucky.


"Never in my experience have such widely divergent groups of people, coming from traditions so vastly different, been brought together under one roof around a gratifying theme like this," said Ruff, who is black and a native of Sheffield, Ala.


Ruff is convinced that "presenting the line"—the unaccompanied singing of psalms in Gaelic by Presbyterians of the Scottish Hebrides—is the direct antecedent of "lining out," a hymnal style of singing of 19th century slaves that is still practiced by a dwindling number of Southern churches.


Ruff--a bassist and French horn player who played with Miles Davis, Duke Ellington and Dizzy Gillespie-- believes that "lining out" evolved into the call-and-response of spirituals and gospel music that, in turn, influenced  virtually every other type of American music.


In traditional line singing, a designated person sings a line solo, inviting congregation members to follow in their own time and with their own harmonies. The result is an echoing, surging and radiant chorus that critics have likened to waves of music crashing against the walls of a church.


Ruff's work has received extensive publicity in Scotland, where some news accounts and Internet postings contend his findings prove the Scots invented gospel music. Though he regards that claim as vastly overstated, he said his research shows that gospel and other American musical forms have roots somewhere other than the slaves' native Africa.


Hugh Foley, a communications and fine arts professor at Rogers State University in Claremore, Okla., said the connections among the ethnic groups provide a fascinating insight into how American music formed.