section_path: Traditional folk music/Folk song transformations and variations
section_name: Folk song transformations and variations
paragraph_text: Folk song transformations and variations
  
  Music transmitted by word of mouth through a community, in time, develops many variants, since this transmission cannot produce word-for-word and note-for-note accuracy. In addition, folk singers may choose to modify the songs they hear.
  
  For example, around 1970 the song Mullā Mohammed Jān spread from Herat to the rest of Afghanistan, and Iran where it was recorded. Due to its repetitive refrain and the predictability of the second half of each verse, it allowed for both its popularization, and for each singer to create their own version of the song without being overly-concerned for a melody or restrictive poetic rhythm.
  
  Because variants proliferate naturally, there is generally no "authoritative" version of song. Researchers in traditional songs have encountered countless versions of the Barbara Allen ballad throughout the English-speaking world, and these versions often differ greatly from each other. The original is not known; many versions can lay an equal claim to authenticity.
  
  Influential folklorist Cecil Sharp felt that these competing variants of a traditional song would undergo a process of improvement akin to biological natural selection: only those new variants that were the most appealing to ordinary singers would be picked up by others and transmitted onward in time. Thus, over time we would expect each traditional song to become more aesthetically appealing, due to incremental community improvement.
  
  Literary interest in the popular ballad form dates back at least to Thomas Percy and William Wordsworth. English Elizabethan and Stuart composers had often evolved their music from folk themes, the classical suite was based upon stylised folk-dances, and Joseph Haydn 's use of folk melodies is noted. But the emergence of the term "folk" coincided with an "outburst of national feeling all over Europe" that was particularly strong at the edges of Europe, where national identity was most asserted. Nationalist composers emerged in Central Europe, Russia, Scandinavia, Spain and Britain: the music of Dvořák, Smetana, Grieg, Rimsky-Korsakov, Brahms, Liszt, de Falla, Wagner, Sibelius, Vaughan Williams, Bartók, and many others drew upon folk melodies.