The answer is, at least since 1893.
Following Yale Professor Willie Ruff's revelation in 2003 that the Negro spiritual really was derived from a Scottish musical tradition, I began to wonder when the myth of the originality of Negro music had begun, and whether any expert had taken the trouble to attack the claim when it was still new and still would have struck people as outrageous. I found such an expert in Austrian musicologist Richard Wallaschek (1860-1917), known for his work in comparative musicology and psychology of music.
According to Wallaschek "the first to try to make negro songs known" were J.M. McKim with an article published in August 1862 and H.G. Spaulding with a publication in August 1863. These were both published during the War between the States, contemporary with the Emancipation Proclamation, (issued in two parts, in September 1862 and January 1863). Also, be it known that McKim and Spaulding made their song collections during the Union's military occupation of the Sea Islands, which had begun in November 1861; ipso facto the collection was made without input from local Whites, from whom the Blacks might have learned the songs. What we have seen in the exaggeration of Negro creativity is propaganda -- originally war propaganda -- with scholarly pretensions. The promulgation of the myth of "Negro spirituals" was to argue the humanity of the Negroes as a people capable of creating culture and thus undeserving of servitude -- indeed, deserving social equality with Whites.
Significantly, the most famous speech of the post-slavery agitation for racial equality, M.L. King's "I have a Dream" speech, ends with a quote (albeit distorted and misrepresented*) from a so-called Negro spiritual.
This propaganda has taken a new turn with the popularity of rock music since the 1950s. Young White people were taught that their own preferred music somehow had roots in Africa, and that therefore they were hypocrites if they did not have a high opinion of Blacks. It is of course the Jewish-dominated mass-media, marketing rock music, that has conveyed this message.
Scholars knew that the cultural contribution of Blacks was being exaggerated, but amid the equality-propaganda of the mass-media their influence was nil. According to Dena J. Epstein ("A White Origin for the Black Spiritual? An Invalid Theory and How it Grew," American Music, Summer 1983), Wallaschek's position was "widely accepted among the academic community while it was virtually unknown to the public at large." In other words, mass-media continued to make the public believe in the reality of Negro spirituals even though scholars knew that it was a hoax. "When interest in black studies exploded in the 1960s, the theory became something of an embarrassment, and some reference books avoided the controversy by omitting articles on the subject altogether." In other words, even scholars began to be overwhelmed by the mass-media's propaganda. Scholarship was pressured to conform to vulgar beliefs that the mass-media had created. "The theory continued to live in other reference books and older volumes still on library shelves, however."
I have reproduced the relevant section from the most important of the "older volumes" below, followed by a mainstream news report from 2003 about Professor Ruff's finding, for those who missed it.
A respected 19th-century Scholar assesses the musicality of Negroes
(From Richard Wallaschek, Primitive Music: an Inquiry into the Origin and Development of Music, Songs, Instruments, Dances, and Pantomimes of Savage Races, Longmans, Green, and co., New York 1893: pp. 60-62)
There still remains to be mentioned one race which is spread over all America and whose musical powers have attracted the attention of many Europeans — the negro race. It may seem inappropriate to treat of the negroes in this place, but it is of their capabilities under the influence of culture that I wish to make a few remarks. I think I may say that, speaking generally, these negro-songs are very much overrated, and that as a rule they are mere imitations of European compositions which the negroes have picked up and served up again with slight variations. Moreover, it is a remarkable fact that one author has frequently copied his praise of negro-songs from another, and determined from it the great capabilities of the blacks, when a closer examination would have revealed the fact that they were not musical songs at all, but merely simple poems. This is undoubtedly the case with the oft-quoted negro-songs of Day [Charles William Day, Five Years' Residence in the West Indies, vol. II, Colburn & Co., London 1852, p. 121] and Busch [Moritz Busch, Wanderungen zwischen Hudson und Mississippi 1851-1852, Stuttgart 1854: 61, 73]. The latter declares that the lucrative business which negroes made by singing their songs in the streets of American towns determined the whites to imitate them, and with blackened faces to perform their own "compositions" as negro-songs. We must be on our guard against the selections of so-called negro-songs which are often offered to us as negro compositions.
Miss M'Kim [J.M. McKim, "Negro Songs," Dwight's Journal of Music, Boston, 9 August 1862] and Mr. Spaulding [H.G. Spaulding, "Under the Palmetto," Continental Monthly, August 1863] were the first to try to make negro-songs known, the former of whom, in conjunction with Allen & Ware, published a large collection [William Francis Allen, Charles Pickard Ware, Lucy McKim Garrison, Slave Songs of the United States, A. Simpson, New York, 1867] which for the most part had been got together by the negroes of Coffin's point and in the neighbouring plantations at St. Helena [South Carolina]. I cannot think that these and the rest of the songs deserve the praise given by the editors, for they are unmistakably "arranged" — not to say ignorantly borrowed — from the national songs of all nations, from military signals, well-known marches, German student-songs, etc., unless it is pure accident which has caused me to light upon traces of so many of them. Miss M'Kim herself says it is difficult to reproduce in notes their peculiar guttural sounds and rhythmical effects, almost as difficult, in fact, as with the songs of birds or the tones of an aeolian harp. "Still the greater part of negro-music is civilised in its character," sometimes influenced by the whites, sometimes directly imitated. After this, we may forego the necessity for a thorough examination, although it must be mentioned here, because the songs are so often given without more ado as examples of primitive music. It is, as matter of fact, no longer primitive, even in its wealth of borrowed melody. Feeling for harmony seems fairly developed. Soyaux heard melodies sung by negro girls in Sierra Leone — their African home — which were accompanied with perfectly correct harmonies. Barbadoes negro melodies must be excepted from the half-civilised negro music of North America— as Mrs. [Evelyn] Martinengo-Cesaresco ["Negro Songs from Barbados," The Folk-Lore Journal, 1887] observes — although she agrees that they lose their original character very quickly under the influence of the whites. To these belong to a certain extent some songs of the Bahama negroes (east from Cuba) which were sung before the hut of a dying friend and which had reference to his death : —
If every day was Judgment day, somebody's dying here to-day.
This verse must have made a strange impression on the sick person. Mention, too, must be made of the "song of the porters" at Rio de Janeiro, which is nothing but a "call" to render the work easier and more regular.
Gospel truth: Hebrides invented church spirituals
By Paul Kelbie, Scotland Correspondent
Saturday, 20 September 2003
A study into the roots of gospel music by an American professor has lead the accomplished musician, who has played with Duke Ellington and Dizzy Gillespie, to conclude that the "good news" music sung in black American churches originated from Scotland, not Africa.
Professor Willie Ruff, of Yale University, said the roots of the music derived from evangelical spirituals and blues and jazz, had more to do with the crofters of the Outer Hebrides than slaves on US plantations.
For years the accepted wisdom has been that gospel music was born during the period of slavery in the Deep South. But Professor Ruff conceded that his findings have startled a number of elders in black churches.
"They have always assumed that this form of worship came from Africa," Professor Ruff, an Afro-American professor of music, said. "Black Americans have lived under a misconception. Our cultural roots are more Afro-Gaelic than Afro-American. Just look at the Harlem telephone book, it's more like Edinburgh or the book for the North Uists.
"There is a notion that when African slaves arrived in America they came down the gangplanks of slave ships singing gospel music - that's just not true. What I'm talking about here pre-dates all other congregational singing by blacks in America."
Traditional psalm singing, or "precenting the line" as it is correctly known, in which the psalms are called out and the congregation sings a response, was the earliest form of congregational singing adopted by Africans in America. Even today, psalm singing and gospel music are the backbone of black churchgoers in the US, with CD sales alone worth half a billion dollars last year.
But Professor Ruff, 71, a Baptist from Alabama, said: "I, like everyone else, assumed it was unique to black congregations in the United States, having grown out of slavery, but I began to wonder if it was performed by white congregations in the same way," he said.
He began researching at the Sterling library at Yale, one of the world's greatest collections of books and papers, where he found records of how Highlanders settled in North Carolina in the 1700s.
"Scottish emigrants from the Highlands, and the Gaelic speaking Hebrides especially, arrived in parts of North Carolina in huge numbers and for many years during the slavery period black Africans, owned by Scottish emigrants, spoke only the Gaelic language. I found, in a North Carolina newspaper dated about 1740, an advertisement offering a generous reward for the capture and return of a runaway African slave who is described as being easy to identify because he only speaks Gaelic. There is no doubt the great influx of Scots Presbyterians into the Carolinas introduced the African slaves to Christianity and their way of worship," he said.
But it wasn't until Professor Ruff travelled to Scotland that he became convinced of the similarities after hearing psalm singing in Gaelic. "I was struck by the similarity, the pathos, the emotion, the cries of suffering and the deep, deep belief in a brighter, promising hereafter.
"It makes sense that as we got our names from the slave masters, we carried the slave owners blood, their religion and their customs, that we should have adopted and adapted their music. There are more descendants of Highland Scots living in America than there are in the Highlands - and a great many of them are black.
"I have been to Africa many times in search of my cultural identity, but it was in the Highlands that I found the cultural roots of black America."
Jamie Reid-Baxter, a history research fellow at Glasgow University and a psalm expert, said: "The Scottish slave-owners would definitely have brought that style of singing with them and the slaves would have heard it. Both these forms of music are a way of expressing religious ecstasy."
* "Free at last, Free at last, I thank God I'm free at last," is from American Negro Songs by John W. Work, published (significantly, amid the Civil Rights offensive) in 1960. Both the words and the meaning of this "old Negro spiritual," as King called it, were substantially altered by King in his speech. King said, "Free at last! Free at last! Thank God Almighty, we are free at last!" by which he meant the achievement of social equality for the Negro. The original song, correctly understood, does not in any way support this agenda; it is about the freedom from physical pains and limitations that comes with death, an idea very old in the European tradition, espoused by Socrates in Plato's Phaedo. The song has the call-and-response form that Professor Ruff found to be typical of songs from Hebrides.