Even so, some authors trace the origins of the morna back to a musical genre — the lundum — that would have been introduced into Cape Verde in the 18th century. There is also a relationship between the morna and another musical genre that existed already in the islands, the choros, which are plaintive songs performed on certain occasions, such as the working songs and wake songs. The morna would be, then, a cross between the choros and the lundum, with a slower tempo and a more complex harmonic structure. Some authors claim that speeding up the tempo of some older songs from Boa Vista or even the song “Força di cretcheu” from Eugénio Tavares, produces something very close to the lundum.